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Sigma bands in the near-ultraviolet absorption spectrum of 12C34S2
JOURNAL
OF MOLECULAR
SPECTROSCOPY
I13,275-285
Sigma Bands in the Near-Ultraviolet
(1985)
Absorption
Spectrum of 12C34S2
J. L. HARDWICK’ Radiation Laboratool, University cf Notre Dame, Notre Dame, Indiana 46556 AND C.
J. SELISKAR
Department of Chemistry, University of Cincinnati, Cincinnati, Ohio 45221 The absorption spectrum of ‘*C”S2 has been examined at high resolution in the region between 3350 and 3900 8, (Kleman’s R system). Thirty Z bands have been identified and rotationally analyzed, yielding vibrational isotope shifts and rotational constants for the (0,2.0) and (0.4.0) levels of the ground electronic state and for levels of the excited electronic state having u, = 0 and I, o2= 3 through 1I, and ug = 0 and 2. 0 1985 Academic press, IW. INTRODUCTION
Although there are many examples of spin-forbidden transitions in polyatomic molecules, few have succumbed to a rotational analysis. Among these, the only analysis demonstrating strong spin-orbit coupling in the excited electronic state [Hund’s case (a)] is that for the near-ultraviolet system of CS2. Accordingly, a significant amount of the insight into the spectra of second-row and heavier molecules is based on our understanding of the 3A2-‘Zg band system of CS2. This system was first rotationally analyzed by Liebermann (I), who demonstrated that the system obeys parallel-band selection rules (2). The vibrational structure of the system was investigated in detail by Kleman (3) who designated the principal bands as the 'R'system. Kleman, and later Douglas and Milton (4), reported that the system is characterized at low energies by simple vibrational and rotational structure, but becomes very complicated and highly perturbed as vibrations are excited. As has been shown by Douglas and Milton (4) and Hougen (5) the upper state consists of a bent 3& electronic state exhibiting strong spin-orbit coupling. In consequence, the intensity of the system is carried mostly by states of B2 spin-vibronic symmetry having multiple quanta ofthe bending vibration (Q) excited. The remaining spin components carry relatively little intensity, and have been reportedly observed only in the solid state (6). As it seems probable that the upper state of the R system correlates with a 3AUelectronic state of the linear molecule (6-9). the complexity of the bands at higher energy is not altogether unexpected. Indeed, the proximity of six interacting spin-electronic states suggests that the problem of deperturbing the vibronic bands will likely require more information than is available from a single isotopic species. ’ Present address: Department of Physics, University of Oregon. Eugene, Oregon 97403. 275
0022-2852/85 $3.00 Copyright 0
1985 by Academic Press. Inc.
All rights of reproduction in any form reserved
276
HARDWICK
AND SELISKAR
In the present paper, we report rotational analyses for sigma (Z) bands (i.e., K:, = I” = 0) in the region between 3900 and 3350 A for ‘2C34S2,The analyses are restricted to 2 bands, and so the reported band origins give direct measurements of the excited state vibronic term values. These term values, together with those for corresponding features in other isotopic species, should provide a starting point for determination of isotope-independent potential functions for the two states. In addition, isotope shifts are necessary to establish the relationship between the R system and the so-called S and U systems reported by Kleman (3). Work on the ground state vibrational levels of ‘2C34S2has been reported by Blanquet et al. (11-13). We have been able to extend their analyses to the (0, 4, 0)” vibrational level in the present work. EXPERIMENTAL
DETAILS
Spectra between 3900’ and 3350 A were recorded in the seventh and eighth orders of a 7-m asymmetric Czerny-Turner spectrograph at a reciprocal dispersion between 1.1 and 1.3 cm-‘/mm. This instrument has been described in detail elsewhere (14). The orders of the grating were separated using a grating predisperser (Instruments SA, Model HR- 10). The pressure of the sample varied from 1 to 100 Torr, and the optical pathlength was varied between 6 and 36 m using a White-type multiple-reflection cell having a base path of 1.5 m. Spectra were recorded photographically using SA- 1 and 103a-0 plates at exposure times ranging from 1 to 30 min. Wavelength calibration was performed using the lines of an iron-neon hollow-cathode lamp in all orders of the grating. The plates were measured to an accuracy of 1 pm both with a computercontrolled microdensitometer and with a Jarrell-Ash manually operated comparator retrofitted with a Bausch and Lomb ACU-RITE II optical linear encoder. Widths of the CS2 absorption lines were found to be in good agreement with the calculated Doppler width of 0.04 cm-‘. We estimate the relative precision of strong, unblended lines from the same plate to be approximately 0.01 cm-‘, and believe the absolute error in wavenumber to be no worse than 0.05 cm-’ over the range quoted. The sample of ‘2C34S2was obtained from Monsanto Research Corporation, Mound Laboratory, Miamisburg, Ohio. The atomic isotope composition was 95.6% 12C,4.4% 13C. and 6.0% 32S 1.7% 33S, 90.6% 34S, 1.6% 36S; and the molecular composition included 8 1% ‘2C3’S2, 9% ‘2C32S34S,and 0.4% ‘*C3*S2. RESULTS
AND DISCUSSION
Vibrational and Rotational Assignments Table I lists the wavelengths in air and the vacuum wavenumbers of the prominent bandheads in the absorption spectrum of ‘2C34S2.The vibrational assignments were, for the most part, based upon those of Kleman (3). The bands exhibit isotope shifts ranging from 15 to 40 cm-’ to the red of the normal isotope, and the appearance of the rotational structure of a given band was usually sufficient to establish the value of Kb. In addition, the rotational constants of the Z bands allowed unambiguous identification of the lower vibrational state whenever rotational analysis was possible. Intensities were also found generally to follow the observations of Kleman. Since the ground state vibrational constants for u2and 3u2are not available, the rotational analysis
277
‘2C34SzUV SPECTRUM TABLE I Assignments of Prominent Bandheads in the a3A2-X’Z, Band System of C34S2
x/n 3363.9765 3374.2237 3393.4636 3398.9804 3404.0928 3410.2339 3412.7886 3393.4636 3423.6177 3441.6726 3455.7316 3463.7546 3470.4823 3470.6383 3473.3293 3487.9545 3494.3424 3502.5724 3502.7203 3505.7348 3511.4539 3511.4983 3516.2920 3522.0775 3522.5913 3524.0622 3527.6213 3527.7026 3527.1918 3533.8043 3539.4686 3542.4493 3543.1764 3547.7124 3549.4439 3553.7372 3553.9645 3554.7719 3555.0533 3555.2451 3562.1721 3563.4347 3572.4296 3575.0517 3576.5461 3576.7409 3579.1237 3581.3984 3582.3295 35813.6430 3588.8954 3590.5666 3594.5535 3602.0884 3606.7582 3613.2779 3613.7521
v/cm-l 29718.2 29627.9 29459.9 29412.1 29368.0 29315.1 29293.1 29460.0 29200.5 29047.3 28929.1 28862.1 28806.1 28804.9 28782.6 28661.9 28609.5 28542.3 28541.1 28516.5 28470.1 28469.7 28430.9 28384.2 28380.1 28368.2 28339.6 28339.0 28343.1 28290.0 28244.8 28221.0 28215.2 28179.1 28165.4 28131.4 28129.6 28123.2 28121.0 28119.4 28064.7 28054.8 27984.2 27963.6 27952.0 27950.4 27931.8 27914.1 27906.8 27057.7 27855.8 27842.8 27811.9 27753.8 27717.8 27667.8 27664.2
h/A
assignment
(0.6.2) - (0.0.0) G"5 2) - (O,O,O) 4; ; 3u - (0.0.0) r
&.O)(0.5.2) (0.4.2) (O.lO,O)(Of3.2) (1.7.0) (0,4,2) (0,482) (0,9.0) (0,5.2) (0,10.0)(0~3.2) (0.3,2) (0.8.0) (1.7.0) (1.7.0) (0.4.2) (0.9,O) (0,9.0) -
(0;o.o)
e
(0.0.0) (0.0.0) (0.0.0) (0,O.O) (O,O,O) (0,l.O) (0.1.0) (0.0.0) (0.2.0) (0.1.0) (O,l,O) (0.1.0) (0.0.0) (0.1.0) (O,l,O) (0.2.0) (0,l.O) (0,l.O)
z E E z z n n E h II? II n z n n A ll II
(0,o:o) E
(0.1.2) - (0,O.O) I: (1.5.0) - (0.0.0) z (1,E.O) (0,7,0) (1.6,0) (1.6,O) (0,3,2)
-
(0.2.0) (0,O.O) (0.1.0) (0.1.0) (0.2.0)
XI I II? n? A
(0.3.2) - (0,Z.O) z (0.8,O) - (0.1.0) II? (0.8.0) - (0.1.0) li? (1,7.0) (1.4.0) (0.9,O) (0.6,o) (1.5.0) (1.5.0)
-
(0.2.0) (0.0.0) (0.2.0) (0,O.O) (0,l.O) (0,l.O)
2 c E E n n
(0.2,2) (0.7,O) (0,7,0) (l-6,0) (1.6.0) (0.8.0) (0.8.0) (1.4.0) (1,4,0)
-
(0,2.0) (0.1.0) (0,l.O) (0,2,0) (0.2.0) (0.2.0) (0.2.0) (0,l.O) (0.1.0)
A n n A? E? A z n II
3615.9303 3625.0878 3625.2706 3625.4442 3629.8251 3629.9033 3630.4808 3635.7143 3637.1978 3637.2116 3638.3482 3642.3707 3646.5900 3647.9946 3650.3546 3651.8008 3652.3482 3658.0576 3663.0807 3663.2031 3663.4875 3667.8366 3673.6951 3674.8196 3680.0950 3682.7440 3683.0183 3683.3031 3684.7408 3684.7932 3685.1925 3685.7024 3686.3024 3689.9570 3695.6125 3695.9269 3698.6415 3702.7118 3703.0167 3703.0769 3703.1241 3707.6174 3712.6896 3714.1848 3714.2104 3719.1943 3721.7438 3723.8974 3734.2591 3734.7881 3735.4970 3740.3246 3748.2193 3753.5706 3754.0066 3755.2003 3759.1611
v/cm-l 27647.5 27577.7 27576.3 27575.0 27541.7 27541.1 27536.7 27497.1 27485.9 27485.8 27477.2 27446.8 27415.1 27404.5 27386.8 27375.9 27371.8 27323.2 27291.7 27290.7 27288.6 27256.3 27212.8 27204.5 27165.5 27145.9 27143.9 27141.R 27131.2 27130.8 27127.9 27124.1 27119.7 27092.9 27051.4 27049.1 27029.3 26999.5 26997.3 26996.9 26996.5 26963.8 26927.0 26916.2 26916.0 26879.9 26861.5 26846.0 26771.5 26767.7 26762.6 26728.0 26671.8 26633.7 26630.6 26622.2 26594.1
assignment (0,6,0) (1,5,0) (0,6,0) (0.1.2) (1.5.0)
- 0,l.O) n - 0.2.0) A - '0.1.0) " - 0,2.0) z - 0.2.0) z
(1.6.0) (0.7.0) (0.7.0) (0,2,2) (0.7.0) (1.6.0) (0.8.0) (0,4,0) (1.3.0)
- '0.3.0) m - 0.2.0) A - '0.2,O) A - 0.3.0) n - 0.2.0) L - 0.3.0) n - 0.3.0) m - 0.0.0) L - O.l,O) n
(O.E,O) (0.5,0) (1.4,o) (0.5,O) (1.4,O) (1.5,O) (0.6,0) (0.6,O) (1,5,0) (1,5.0)
-
(0.3,O) (0,l.O) (0.2.0) (O.l,O) (0.2.0) (0.3.0) (0.2.0) (0,2,0) (0,3.0) (0.3,O)
II n A II I: m A c II II
(0#7,0) - (0.3.0) 0 (0.7,O) - (0.3.0) m
(0.2.2) (0,7,0) (0,7.0) (lf6.0) (0.4.0) (0.4,O) (1.3.0) (1.3.0) (1.3,O) (1.4.0) (0,5.0) (0.5,o) (O-5,0) (1.4.0) (0.6.0) (0.6,0) (0.6.0) (1,5.0) (1.5.0) (0.7.0) (0.7.0) (1.3,O) (0.4.0)
-
(0.4,0) (0,3,0) (0,3.0) (Oe4.0) (0.1.0) (0.1.0) (0.2.0) (0.2.0) (0.2,O) (0.3.0) (0.2,0) (0.2,O) (0.2.0) (0.3.0) (0,3.0) (0,3.0) (0,3.0) (0.4,O) (0;4.0) (0.4.0) (0,4.0) (0,3,0) (0.2.0)
A n n A n n A A L 0 A A h n $ n n A c A z 8 A
of IT and higher-K bands would not be profitable at this time. Without these lower state constants, determination of the rotational constants A, for the excited electronic state is not possible. Since the isotope shifts of bandheads are critically dependent on both the change in the vibrational energy and the change in the rotational constant between the isotopic species, the bandhead positions cannot be used in a straightforward way to refine the molecular Hamiltonian. The Z bands were, therefore, rotationally analyzed to determine the vibrational band origins and effective values of the B rotational constants,
HARDWICK
278
AND SELISKAR
TABLE I-Continued
3759.9526
3762.0248 3762.6611 3764.8269 3164.8472 3114.5992 3775.1978 3775.8278 3780.7763 3788.1712 3793.7240 3797.7441 3799.7901 3802.2967 3805.3963 3807.4440 3811.1062 3811.2720 3815.2047 3816.6903 3817.2813 3818.2054 3820.8917 3823.0606 3829.1885 3829.5163
26588.5 26573.9 26569.4 26554.1 26554.0 26485.4 26481.2 26476.7 26442.1 26390.5 26351.8 26323.9 26309.8 26292.4 26271.0 26256.9 26231.7 26230.5 26203.5 26193.3 26189.2 26182.9 26164.5
(0.4.01 1;3;oj 1,3.0) 0,5,0) 0,5,0) 0,5.0) 0.5.0) 1,4,0) 1,4.0) 0,6.0) 0.6.0) 0.3.0) 0,7,0) 0.3.01 l-2,0) 0,4.0) 0.7.0) 0,7.0) 0.5.0) 0.4.0) 0.4.0) 1.3,O)
-
(0.2.0) io;3;oi (0.3.0) (0.3.0) (0,3,0) (0.3,0) (0.3.0) (0,4.0) (0.4.0) (0,4,0) (0.4.0) (0.2.0) (0,5,0) (0.2.0) (0,3,0) (0.3.0) (0.5.0) (0.5.0) (0.4.0) (0.3.0) (0.3.0) (0.4.0)
z
h
m E II
m n I1 I-
n n b
(1.3.0) - (0,4.0) E ;;a;;.; 26105:6
(1.4.0) - (0.5.0) Q
3829.9361 3830.0325 3830.0746 3835.2992 3838.8933 3841.3969 3846.1795 3851.5500 3852.2061 3854.3937 3859.5197 3860.4142 3861.0149 3865.3700 3873.4633 3873.6667 3873.7181 3878.6723 3882.5060 3884.9995 3895.1541 3918.9520 3919.0145 3923.7608 3930.3898 3939.9962
26102.7 26102.0 26101.7 26066.2 26041.8 26024.8 25992.5 25956.2 25951.8 25937.1 25902.6 25896.6 25892.6 25863.4 25809.4 25808.0 25807.7 25774.7 25749.3 25732.7 25665.7 25509.8 25509.4 25478.5 25435.6 25373.6
(0,5.0) - (0.4.0) n (0,5#0) - (0,4.0) A (0.5,O) - (0.4,O) E (Oe6.0) - (0,5,0) m (0.6.0) - (0.5.0) n (0,4.0) - (0.4.0) r (1.3,0) (1,3,0) (0.4.0) (0.4,0) (0.4.0) (1,3.0) (0.5.0) (0,5.0) (0.3,0)
-
(0,S.O) (0,5,0) (0.4.0) (0.4,0) (0,4.0) (O.S,O) (0.5.0) (O.S,O) (0.4.0)
H m A A z II m n b
(0.3.0) - (0,4,0) z (0.4.0) - (0,5.0) @
each of which is essential to an adequate development of a molecular potential function. The observed line positions for these bands are presented in Table II. Constants for the ground vibrational level of the lower electronic state were held fixed at the values determined from the infrared spectra of Blanquet et al. (11-13). The vibrational and rotational constants for the (0, 2,O)” state were determined from a combination of infrared data (II) and the present ultraviolet measurements. The constants for (0, 4, 0)” were determined from the ultraviolet data alone. Since the rotational structure of the excited vibronic states is perturbed, determination of the ground state vibrational and rotational constants was accomplished by simultaneously fitting all vibrational and rotational combination differences which could be obtained from differences of the measured line positions. The constants thus obtained are presented in Table III. These were held fixed in subsequent simultaneous fittings of the line positions of several bands in order to determine the term values and rotational constants of the upper electronic state. These constants are presented in Table IV. The calculated line positions and residuals of Table II were computed using these constants. The bands at 293 15 and 29368 cm-’ arise from the ground vibrational level of the lower electronic state, but the upper vibronic state has no obvious and unambiguous assignment. They are designated as 1U and 3U by analogy with nearby bands in Kleman’s spectrum, although it should be emphasized that the vibrational state need not be the same as that of the bands in the normal isotope bearing the same labels. The rotational constants, intensity, and isotope shifts suggest that these are higher vibrational states of the R system. Perturbations Even at low vibrational quantum numbers, the vibrational spacing is somewhat irregular, and the vibrational energies cannot be represented by a rapidly converging
TABLE II Rotational Assignments for the Cold Z Bands of the a’& Electronic State of C34Sz(All line positions are in cm-‘. Complete assignments of the hot Z bands are available from the journal or the authors on request.)
(0,6.0)
(0.4.0) - (O,O,O) J
PIJ) obs
14 16 18 20 22 24 26 28 30 32 34 36 38 head
R(J) o-c
27388.894 27388.648 27388.384 27388.147 27387.890 27387.702 27387.533 27387.366
-0.035 -0.008 -0.017 -0.018 -0.058 -0.048 -0.036 -0.041
27387.089 27387.021
-0.048 -0.008
27386.73
obs
-0.002 -0.025 -0.014 -0.001
27399.351 27400.036 27400.758 27401.500 27402.248 27403.007
-0.030 -0.040 -0.031 -0.019 -0.013 -0.025
-0.01
obs 16 18 20 22 24 26 28 30 32 34 36 38 40 head
27965.207 27964.996 27964.762 27964.610 27964.365
27963.60
(0,5,0) - (O,O,O) P(J)
J
obs 4 6 8 10 12 14 16 18 20 24 26 28 30 32 36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 66 68 70 72
27680.511 27680.289 27680.048 27679.755
-0.096 -0.026 0.007 -0.032
obs
J o-c
27683.750 27684.398 27684.806 27685.305 27685.804 27686.410 27686.931 27687.538 27688.157 27689.403 27690.075 27690.768 27691.468 27692.218 27693.537 27694.368 27695.134 27695.948 27696.765
27697.622 27698.467 27699.334 27700.211 27701.139 27702.042 27702.950 27703.899 27704.822 27705.836 27706.791 27707.804 27708.792 27709.809
-0.106 0.069 -0.014 -0.026 -0.057 0.001 -0.045 -0.024 -0.010 -0.028 -0.015 0.000 0.005 0.041 -0.119 -0.053 -0.069 -0.055 -0.054 -0.029 -0.032 -0.029 -0.032 0.001 -0.006 -0.023 -0.013 -0.044 0.003 -0.023 -0.004 -0.022 -0.024
14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 head
6 8 10 12 14
o-c
27966.441
-0.012
27965.853 27965.513
0.030 -0.025
o-c
27972.219 27972.738 27973.462 27974.057 27974.713 27975.412 27976.084 27976.766 27977.454 27978.268 27979.030 27979.823 27980.617
0.001 -0.076 0.032 -0.009 -0.007 0.018 -0.002 -0.031 -0.072 -0.006 -0.009 0.001 -0.006
0.02
obs
-0.019 -0.021 -0.026
27971.619
-0.022
28244.76
J
0.079 0.061 0.047
obs
o-c
28251.914 28252.532 28253.203 28253.899 28254.598 28255.340 28256.088 28256.850 28251.646 28258.417 28259.269 28260.049 28260.953 28261.817 28262.733 28263.648 28264.605 28265.571 28266.559
0.057 0.029 0.030 0.032 0.015 0.021 0.012 -0.001 0.002 -0.037 -0.011 -0.073 -0.027 -0.037 -0.011 -0.005 0.023 0.045 0.051
0.07
P(J) obs
2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36
0-c
27969.515 27970.010 27970.522
28245.569 28245.375 28245.209
R(J) 0-c
(o.8,o) - (o,o,o)
R(J)
P(J) obs
0.013 -0.033 -0.042 0.012 -0.047
obs
P(J) obs
(0.6,0) - (o,O,o) J
R(J) o-c
(0,7,0) - (O,O,O) R(J)
o-c
l0.0.0)
P(J)
J
o-c
27396.174 27396.156 27397.389 27398.043
-
279
28520.779 28520.386 28520.012 28519.682 28519.352 28519.043 28518.758 28518.504 28518.249 28518.027 28517.813 28517.632 28517.453 28517.295 28517.142
R(J) o-c
0.011 0.003 -0.007 0.007 0.000 -0.006 -0.008 0.002 -0.009 -0.005 -0.012 -0.004 -0.011 -0.015 -0.029
obs 28521.829 28522.270 28522.755 28523.240 28523.772 28524.305 28524.868 28525.435 28526.041 28526.652 28521.282 28527.936 28528.593 28529.279 28529.993 28530.700 28531.429 28532.174
0-c 0.008 -0.009 -0.002 -0.015 -0.001 -0.007 -0.002 -0.012 -0.002 -0.005 -0.008 -0.003 -0.013 -0.010 0.005 -0.002 -0.001 0.002
280
HARDWICK
AND SELISKAR
TABLE II-Continued (0,8,0)
J
(O,O,O)
-
38 40 42 44 46 48 head 52 54 56
28516.50
obs
0-c
28532.919 28533.678 28534.476 28535.267 28536.063 28536.878 28537.700 28538.534 28539.352 28540.196
-0.06
(0,9,0)
J
2 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 head 50 52
28782.60
J
(O,O,O)
obs
-0.03
-
0-c
28787.836 28788.758 28789.273 28789.790 28790.317 28790.874
0.032 0.021 0.039 0.039 0.030 0.031
28791.457 28792.040 28792.670
0.038 0.026 0.043
28793.283 28793.944 28794.614 28795.300 28796.010 28796.712 28797.426 28798.194 28798.952 28799.736 28800.537 28801.347 28802.153 28802.944 28803.826 28804.686
0.024 0.034 0.036 0.037 0.044 0.027 0.007 0.024 0.017 0.021 0.029 0.033 0.020 -0.019 0.022 0.030
(O,O,O)
P(J) obs
-0.009 -0.018 0.000 0.000 -0.007 -0.004 -0.005 -0.003 -0.025 -0.030
R(J) 0-c
29051.843
-0.010
29051.138 29050.789 29050.438 29050.062 29049.760 29049.441 29049.147 29048.864 29048.658 29048.428 29048.199 29048.041 29047.863 29047.702 29047.574 29047.421
0.049 0.057 0.047 -0.005 0.001 -0.026 -0.044 -0.068 -0.031 -0.033 -0.051 -0.014 -0.012 -0.009 0.011 -0.009
obs
29052.598 29052.997 29053.394 29053.843 29054.324 29054.811 29055.321 29055.809 29056.357 29056.877 29057.477 29058.048 29058.705 29059.323 29059.960 29060.632 29061.327 29062.046 29062.816
0-c
0.129 0.096 0.045 0.030 0.030 0.020 0.016 -0.026 -0.024 -0.066 -0.044 -0.067 -0.020 -0.028 -0.033 -0.018 0.004 0.034 0.100
-
(O,O,O)
P(J)
R(J)
obs
0-c
R(J) 0-c
(0.10.0~
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36
-
P(J) obs
J
R(J)
P(J) obs
(O,lO,O)
38 40 42 44 46 48 head 52 54 56 58 60 62 64 66 68 70 72 74 76 78
0-c
29047.055 29046.90
0.054
4 6 8 10 12 14 16 18 20 22 24 26
-
29296.358 29296.037 29295.733 29295.452 29295.174 29294.938 29294.708 29294.491 29294.307 29294.034
R(J) 0-c
29297.068
obs
0.003 0.007 0.008 0.012 0.000 0.011 0.010 0.003 0.012 -0.085
(1,4.0)
4 6 8 10 12 14 16 18
29298.483
-0.020
29299.442 29299.928 29300.438 29300.985 29301.537 29302.116 29302.714 29303.325 29303.965 29304.587 29305.283 29305.932 29306.626 29307.352 29308.043 29308.784 29309.534 29310.285 29311.070 29311.823 29312.604 29313.432 29314.176
0.006 -0.005 -0.012 -0.001 -0.005 0.000 0.005 0.005 0.016 -0.007 0.027 -0.002 -0.001 0.018 -0.011 -0.004 0.001 -0.004 0.015 -0.007 -0.008 0.030 -0.020
-
(O,O,O)
P(J) obs
28057.925 28057.618 28057.306 28057.009 28056.742 28056.490
0-c
0.003
LO 30 32 34 36 38 40 42 44 46 48 5"
J
0.101 0.167 0.200 0.040 -0.035 -0.029 -0.028 -0.078 -0.123 -0.141 -0.136 -0.061 0.018 0.043 0.062 0.097 0.096 0.018 0.029 -0.068 -0.039
fn.n.01 ,~.~,~,
P(J) obs
0-c
29063.536 29064.337 29065.121 29065.727 29066.434 29067.237 29068.052 29068.832 29069.633 29070.478 29071.363 29072.336 29073.330 29074.289 29075.262 29076.270 29077.263 29078.201 29079.251 29080.216 29081.333
-0.04
cn.11.n) .~.~~.
J
obs
R(J) 0-c
-0.030 -0.007 -0.007 -0.011 -0.004 0.000
obs
28060.603 28061.024 28061.505 28062.051 28062.566 28063.128 28063.674 28064.262
0-c
0.039 -0.013 -0.023 0.013 -0.001 0.014 -0.005 -0.001
281
“C3?S2 UV SPECTRUM TABLE II-Continued
(1,4,0) - (O,O,O) .J
20 22 24 26 28 30 32 34 36 head
R(J)
P(J) obs
o-c
28056.248 28056.015 28055.824 28055.646 28055.482 28055.331 28055.201 28055.072 28054.981 28054.8
(1,7,0) - (O,O,O)
-0.004 -O.OiE -0.007 -0.001 0.002 0.001 0.003 -0.010 -0.001 0.1
J
P(J)
o-c
obs 28064.880 28065.489 28066.117
0.015 0.004 -0.005
28067.418
-0.030
28068.839
-0.003
obs 50
52 54 56 58 60
28872.126 28873.030 28873.936 28874.883 28875.818 28876.736
J
8 10 12 14 16 18 20 22 24 26 28 30 head 34 36 38 40
28339.807 28339.613
28339.0
o-c
-0.040 -0.022
0.2
o-c
obs 28344.300 28344.849 28345.427 28346.033 28346.660 28347.327 28348.042 28348.740 28349.475 28350.208 28350.995 28351.830 28352.657 28353.556 28354.402 28355.280 28356.193
0.044 0.038 0.033 0.030 0.022 0.027 0.055 0.041 0.039 0.011 0.014 0.041 0.039 0.087 0.062 0.049 0.052
(1,7,0) - (O.O,O) J
P(J) obs
12 14 16 18 20 22 24 26 28 30 24 26 28 30 32 34 36 38 40 38 40 42 44 46 48
28862.139 28862.358 28862.545 28862.771 28862.978 28863.168 28863.304 28864.459 28864.793
28865.104 28865.518 28866.026 28866.548 28867.101 28867.642 28868.125 28868.865 28869.586 28870.375 28871.281
R(J) o-c
-0.886 -0.853 -0.912 -0.991 -1.145 -1.371 -1.705 0.336 0.254 0.095 -0.012 -0.073 -0.167 -0.275 -0.436 0.047 0.046 -0.010 -0.031 0.035
o-c
28894.187 28895.918 28897.679 28899.451 28901.175
0.037 0.039 0.055 0.070 0.030
obs
o-c
28867.642 28868.506 28869.428 28870.375 28871.395 28872.426 28873.465 28874.486 28875.431 28876.303
-0.741 -0.761 -0.786 -0.847 -0.895 -0.990 -1.133 -1.350 -1.696 -2.166
28874.883 28876.099 28877.238 28878.474 28879.777 28881.136 28882.498 28883.834
0.285 0.263 0.111 0.005 -0.083 -0.161 -0.28( -0.468
28884.394 28885.917 28887.457 28889.039 28890.786 28892.455
0.092 0.053 -0.004 -0.053 0.033 0.015
head 38 40 42
R(J)
P(J) o-c
obs R(J)
P(J) obs
0.014 0.02R 0.025 0.048 0.046 0.019
obs
(0,1,2) - (0.0.0)
(1,5,0) - (0,O.O) J
R(J) o-c
28339.60
0.01
obs
o-c
28355.013 28355.884 28356.833 28357.636
0.012 0.033 0.108 0.013
(0,3,2) - (O,O,O) J
P(J) obs
2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 40 42 44 46 48 50 52 54 56 58
R(J)
o-c
28931.302 28930.940 28930.640 28930.370 28930.116 28929.894 28929.703 28929.539
0.019 -0.002 0.008 0.017 0.012 0.010 0.009 0.007
28929.15
0.02
obs
o-c
28932.696
-0.025 -0.011 -0.016 -0.006 -0.002 -0.001 0.000 0.009 0.002 0.005 0.007 -0.009 -0.011 -0.018 -0.005 -0.002 -0.015 -0.016 -0.012 -0.004 -0.018 0.011 0.011 0.027 -0.023
28933.191 28933.698 28934.250 28934.826 28935.429 28936.061 28936.730 28937.410 28938.128 28938.871 28939.621 28940.411 28941.221 28942.074 28946.630 28947.598 28948.604 28949.641 28950.710 28951.787 28952.940 28954.106 28955.315 28956.508
(0,4,2) - (O.O,O) J
8 10 12 14 16 18 20 22 24 head
R(J)
P(J) obs
o-c
29201.356 29201.109 29200.907 29200.746 29200.666
0.041 0.012 -0.003 -0.011 0.029
29200.50
0.01
obs 29205.411 29206.009 29206.683 29207.295 29207.960 29208.638 29209.372 29210.142 29210.952 29211.808
o-c -0.057 -0.031 0.040 0.017 0.014 -0.010 -0.011 -0.012 -0.009 0.003
HARDWICK
282
AND SELISKAR
TABLE II-Continued (0,4,21 J
-
C0,O.O)
P(J) obs
1u - (0,O.O) J
R(J) 0-c
28 30 32 34
obs
29212.663 29213.633 29214.594 29215.558
-0.024 0.024 0.023 -0.017
(0,5,2) - (0.0.0) J
P(J) obs
8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 head 42 44 46 48 50 52 54 56 58
R(J) 0-c
obs
o-c
29466.255
29462.326 29462.051 29461.742 29461.371 29461.121 29460.960 29460.747 29460.559
0.025 0.006 -0.094 -0.094 -0.024 -0.027 -0.026
29459.83
-0.02
-0.010
29466.771 29467.247 29467.822 29468.402 29468.980 29469.591 29470.216 29470.878 29471.544 29472.244 29472.956 29473.684 29474.429 29475.242 29476.032
29476.878 29477.723 29478.672 29479.565 29480.540 29481.456 29482.466 29483.429 29484.561 29485.547
0.017 0.021 -0.035 -0.011 -0.002 -0.015 -0.016 -0.023 -0.014 -0.022 -0.017 -0.023 -0.035 -0.052 -0.025 -0.044 -0.031 -0.044 0.021 0.006 0.045 -0.001 0.020 -0.035 0.050 -0.041
P(J) obs
o-c 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 head 42 44 46 48 50 52 54 56 58 60 62 64 66 68 70 72 74
29316.835 29316.586 29316.308 29316.096 29315.911 29315.723
29315.1
R(J) o-c
-0.004 0.016 -0.015 -0.003 0.015 0.008
0.1
obs
o-c
29321.574 29322.119 29322.678 29323.293 29323.911 29324.533 29325.209 29325.898 29326.591 29327.316 29328.068 29328.831 29329.620 29330.410 29331.226 29332.077 29332.932 29333.795 29334.692 29335.597 29336.514 29337.455 29338.403 29339.389 29340.359 29341.348 29342.332 29343.361 29344.370 29345.404 29346.407 29347.449 29348.523
0.011 0.003 -0.013 0.005 0.004 -0.014 0.000 0.006 -0.005 -0.005 0.003 0.001 0.007 -0.006 -0.011 0.001 -0.001 -0.011 -0.004 -0.005 -0.010 -0.004 -0.006 0.017 0.011 0.012 -0.003 0.017 0.007 0.013 -0.019 -0.020 0.005
3u - (O,O,O) J
P(J) obs
R(J) o-c
ohs
0-c
(0.6,2) - (O,O,O) PIJ)
J
obs 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 head
RIJ) o-c
29722.289 29721.894 29721.539 29721.257 29720.877 29720.653 29720.325 29720.050 29719.811 29719.582 29719.387
-0.010 -0.032 -0.031 0.027 -0.031 0.051 0.011 0.007 0.022 0.030 0.053
29718.943 29718.796 29718.650 29718.489 29718.354
-0.007 0.011 0.011 -0.023 -0.049
29718.20
0.05
obs
o-c
29723.701 29724.180 29724.593 29725.130 29725.620 29726.192 29726.720 29727.261 29727.808 29728.392 29729.023
-0.036 -0.006 -0.058 -0.003 -0.012 0.044 0.038 0.029 0.008 0.007 0.035
29730.249 29730.892 29731.572 29732.261 29732.951 29733.673 29734.404 29735.291 29736.087
0.002 -0.011 -0.006 -0.011 -0.034 -0.043 -0.063 0.053 0.058
2 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 head
29372.272
29370.403 29370.130 29369.842 29369.554 29369.296 29369.065 29368.848 29368.665 29368.503 29368.365
29367.95
-0.043 0.012 0.027 0.017 0.012 0.011 0.001 0.001 0.001 0.003
0.06
29373.196 29373.721 29374.251 29374.807 29375.428 29376.005 29376.695 29377.340 29378.013 29378.710 29379.428 29380.199 29380.931 29381.683 29382.502 29383.298 29384.112
0.034 -0.004 0.003 -0.011 -0.023 0.006 -0.032 0.021 0.006 -0.002 -0.007 -0.010 0.022 -0.003 -0.024 0.006 0.001 0.000
283
“C”Sz UV SPECTRUM TABLE III
Vibrational and Rotational Constants for the Ground Electronic State of C34S2(Uncertainties are given as one standard deviation in units of the last significant digit.)
iO,O,Of
0.1027111=
0.984a
(O.Z,O)
797.363(l)
0.1030664(6)
0.941(7)
(0,4.0)
1609.869(5)
0.1033707(3)
0.900"
a.
From
b.
Fixed.
Ref.
(11).
TABLE IV Effective Vibrational and Rotational Constants for the Z Levels of the o3Az Electronic State of C’%> (Vl,V2,V3)
T,'/Crn
-1 RV
a/cm-l
D,'/lo-8c,-1
H eff'/10-12cm-1
(0.3.0)
27095.355
0.105000(21)
2.28(93)
(0.4.0)
27391.367
0.105095(11)
3.72(25)
(O,5*0)
27682.754
0.105092(9)
3.60(18)
(0,6,0)
27967.954
0.105245(6)
4.85(Y)
(O.7,0)
28247.892
0.106493(32)
44.7(24)
64.2(46)
(0,8.0)
28521.167
0.105304(30)
14.3(20)
67.2(35)
(0,9.0)
28787.159
0.105248(21)
(O,lO,O)
29052.260
0.104775(25)
10,11.01
29297.457
0.105256(35)
(1,3.0)
27768.675
0.104669(17)
(1.4,O)
28059.466
0.105083(7)
(1.5.0)
2fl342.095
0.106181(7)
12.7(l)
(1.7.0)
28R64.21a
0.111034
38.
(0.1.2)
28343.4(2Jh
0.105540(30)
(0.3.2)
28932.058
0.106614(44)
(o.4,2)
29203.328
0.106489(121)
8.95(63) 3.771110)
3.92(66) 5.97(15)
0. 27.2(33)
29464.174
0.105102(20)
-5.7(6)
(o.6,2)
29723.096
0.104804(34)
-3.0(20)
29318.928
0.105567(15)
'I3U"
29371.583
0.105914(26)
a.
Severely
perturbed
band:
constants
41.3(64)
-21.0(89)
(0.5.2)
'I1U"
39.(12)
13.4(14)
7.39(28) 20.6(17)
are
estimates.
b. Fragmentary band.
Uncertainties are given as one standard deviation in units of the last significant digit. Rotational and distortion constants without stated uncertainties were held fixed during the calculation. The errors on vibrational term values are believed to be dominated by systematic errors of measurement amounting to about 0.05 cm-‘, except as stated.
284
HARDWICK
AND SELISKAR
Taylor series in the vibrational quantum numbers. This irregularity can be ascribed to vibrational perturbations within the a3A2 state, although the vibrational frequencies of the upper state are so poorly known that the identity of the perturbing state is usually ambiguous. As with the normal isotope, the bands of r2C34S2are rotationally well-behaved near the system origin and become progressively irregular with increasing vibrational energy in the upper state. This irregularity is exhibited both in the rotational constants of those states and in the often severe perturbations to the rotational fine structure. Figure 1 shows an example of the contrast to be found between Z bands which are regular and well-behaved and those which are strongly perturbed. The (0, 6, 0) state, as illustrated by Fig. 1, is largely a well-behaved band, having only a single perturbation at J’ = 6 1 to the observed rotational structure. The ( 1, 7, 0) state, on the other hand, is marked by at least three important avoided crossings, giving rise to bands with a highly irregular appearance. This contrast is also evident from a comparison of the residuals of bands arising from the (0,6,0) and (1,7,0) states in Table II. The residuals of the bands having ( 1, 7,0) as the upper state are substantially in excess of either the experimental error or the error in the ground state combination differences. The (1, 5, 0) level of the upper electronic state (T = 28342.1 cm-‘) is found to be in accidental resonance with a vibronic level which does not appear in Kleman’s spectra of the normal isotope (T = 28343.4 cm-‘). The rotational levels of the two states do not actually cross, but the perturbing band steals enough intensity for a rotational analysis of the band fragments to be possible. On examination, the vibronic origin is found to be approximately one quantum of u; lower in energy than the band designated ‘S’ by Kleman. Kleman’s S band has been assigned by Jungen and Merer (10) to be the (0, 2, 2) band of the R system; we therefore assign the state at 28343.4 cm-’ as the (0, 1, 2) level, although the (3, 0, 0) state cannot positively be excluded.
60
50
40
50
FIG. I. Two representative Z-type bands in the near-ultraviolet spectrum of ‘2C34S2.The (0, 6, 0) band (upper trace) exhibits only a slight irregularity at J’ = 61. while the (1, 7, 0) band (lower trace) suffers from several major perturbations.
‘2C%2 UV SPECTRUM
285
CONCLUSIONS
The near-ultraviolet absorption bands of ‘2C34S2have been measured at high resolution over the region 3900-3350 A. The vibrational and rotational analyses of the Z bands of the Kleman R system have been performed, and the derived constants for the upper and lower electronic states are reported. The R system of the heavy sulfur34 isotope is similar to that of the sulfur-32 isotope in that both show well-behaved bands at low vibrational levels of the B2spin-electronic state which suffer progressively more serious perturbations with increasing vibrational quantum number. The origins of these perturbations are not completely specified, but we can find no conclusive evidence which would implicate a second electronic state as being responsible. The isotope shifts found for the Kleman S bands are large and regular, consistent with the hypothesis of Merer and Jungen (IO) that these bands are derived from excited stretching vibrations of the R system. The 1U and 3 U bands of the heavy isotope appear to be well-behaved, although further work will be necessary before these and higher members of the U progression are positively identified. ACKNOWLEDGMENTS The authors are indebted to Dr. A. J. Merer for communicating the results of his analysis prior to publication. The authors are also grateful to Mr. C. Kinard, Monsanto Research Corporation, for his technical assistance in recording the spectra. The multiple-reflection cell used in this work was based on a design developed at the National Research Council of Canada and kindly provided to the authors by Dr. D. A. Ramsay. This work was supported by the Office of Basic Energy Sciences of the United States Department of Energy. This is Document Number NDRL-2689 from the Notre Dame Radiation Laboratory. RECEIVED:
March 14, 1985 REFERENCES
L. N. LIEBERMANN,Phys. Rev. 60,496-505 (1941). R. S. MULLIKEN,Phys. Rev. 60, 506-513 (1941). B. KLEMAN, Canad. J. Phys. 41,2034-2063 (1963). A. E. DOUGLASAND E. R. V. MILTON, J. Chem. Phyx 41,357-362 (1964). J. T. HOUGEN, J. Chem. Phys. 41, 363-366 (1964). R. M. H~CHSTRASSER AND D. A. WIERSMA,J. Chem. Phys. 54,4 165-4169 (197 I). CH. JUNGEN, D. N. MALM, AND A. J. MERER, Canad. J. Phyx 51, 147 I- 1490 (1973). K.-E. HALLIN, D. N. MALM, AND A. J. MERER, J. Mol. Spectrosc. 54, 318-327 (1975). CH. JUNGEN, D. N. MALM, AND A. J. MERER, Chem. Phys. Lett. 16,302-305 (I 972). A. J. MERERAND CH. JUNGEN,private communication. G. BLANQUET,J. WALRAND, AND C. P. COURTOY,Ann. Sot. Sri. Bruxelles 92,205-221 (1978). J. WALRAND, G. BLANQUET,AND C. P. COURTOY,Ann. Sot. Sci. Bruxelles 93,2 1 l-225 ( 1979). G. BLANQUET,J. WALRAND, AND C. P. COURTOY,J. Mol. Spectrosc. 72, 227-237 (1978). 14. J. L. HARDWICKAND W. J. LAFFERTY.1. Mol. Spectrosc. 100, 358-367 (1983).
I. 2. 3. 4. 5. 6. 7. 8. 9. 10. II. 12. 13.
OF MOLECULAR
SPECTROSCOPY
I13,275-285
Sigma Bands in the Near-Ultraviolet
(1985)
Absorption
Spectrum of 12C34S2
J. L. HARDWICK’ Radiation Laboratool, University cf Notre Dame, Notre Dame, Indiana 46556 AND C.
J. SELISKAR
Department of Chemistry, University of Cincinnati, Cincinnati, Ohio 45221 The absorption spectrum of ‘*C”S2 has been examined at high resolution in the region between 3350 and 3900 8, (Kleman’s R system). Thirty Z bands have been identified and rotationally analyzed, yielding vibrational isotope shifts and rotational constants for the (0,2.0) and (0.4.0) levels of the ground electronic state and for levels of the excited electronic state having u, = 0 and I, o2= 3 through 1I, and ug = 0 and 2. 0 1985 Academic press, IW. INTRODUCTION
Although there are many examples of spin-forbidden transitions in polyatomic molecules, few have succumbed to a rotational analysis. Among these, the only analysis demonstrating strong spin-orbit coupling in the excited electronic state [Hund’s case (a)] is that for the near-ultraviolet system of CS2. Accordingly, a significant amount of the insight into the spectra of second-row and heavier molecules is based on our understanding of the 3A2-‘Zg band system of CS2. This system was first rotationally analyzed by Liebermann (I), who demonstrated that the system obeys parallel-band selection rules (2). The vibrational structure of the system was investigated in detail by Kleman (3) who designated the principal bands as the 'R'system. Kleman, and later Douglas and Milton (4), reported that the system is characterized at low energies by simple vibrational and rotational structure, but becomes very complicated and highly perturbed as vibrations are excited. As has been shown by Douglas and Milton (4) and Hougen (5) the upper state consists of a bent 3& electronic state exhibiting strong spin-orbit coupling. In consequence, the intensity of the system is carried mostly by states of B2 spin-vibronic symmetry having multiple quanta ofthe bending vibration (Q) excited. The remaining spin components carry relatively little intensity, and have been reportedly observed only in the solid state (6). As it seems probable that the upper state of the R system correlates with a 3AUelectronic state of the linear molecule (6-9). the complexity of the bands at higher energy is not altogether unexpected. Indeed, the proximity of six interacting spin-electronic states suggests that the problem of deperturbing the vibronic bands will likely require more information than is available from a single isotopic species. ’ Present address: Department of Physics, University of Oregon. Eugene, Oregon 97403. 275
0022-2852/85 $3.00 Copyright 0
1985 by Academic Press. Inc.
All rights of reproduction in any form reserved
276
HARDWICK
AND SELISKAR
In the present paper, we report rotational analyses for sigma (Z) bands (i.e., K:, = I” = 0) in the region between 3900 and 3350 A for ‘2C34S2,The analyses are restricted to 2 bands, and so the reported band origins give direct measurements of the excited state vibronic term values. These term values, together with those for corresponding features in other isotopic species, should provide a starting point for determination of isotope-independent potential functions for the two states. In addition, isotope shifts are necessary to establish the relationship between the R system and the so-called S and U systems reported by Kleman (3). Work on the ground state vibrational levels of ‘2C34S2has been reported by Blanquet et al. (11-13). We have been able to extend their analyses to the (0, 4, 0)” vibrational level in the present work. EXPERIMENTAL
DETAILS
Spectra between 3900’ and 3350 A were recorded in the seventh and eighth orders of a 7-m asymmetric Czerny-Turner spectrograph at a reciprocal dispersion between 1.1 and 1.3 cm-‘/mm. This instrument has been described in detail elsewhere (14). The orders of the grating were separated using a grating predisperser (Instruments SA, Model HR- 10). The pressure of the sample varied from 1 to 100 Torr, and the optical pathlength was varied between 6 and 36 m using a White-type multiple-reflection cell having a base path of 1.5 m. Spectra were recorded photographically using SA- 1 and 103a-0 plates at exposure times ranging from 1 to 30 min. Wavelength calibration was performed using the lines of an iron-neon hollow-cathode lamp in all orders of the grating. The plates were measured to an accuracy of 1 pm both with a computercontrolled microdensitometer and with a Jarrell-Ash manually operated comparator retrofitted with a Bausch and Lomb ACU-RITE II optical linear encoder. Widths of the CS2 absorption lines were found to be in good agreement with the calculated Doppler width of 0.04 cm-‘. We estimate the relative precision of strong, unblended lines from the same plate to be approximately 0.01 cm-‘, and believe the absolute error in wavenumber to be no worse than 0.05 cm-’ over the range quoted. The sample of ‘2C34S2was obtained from Monsanto Research Corporation, Mound Laboratory, Miamisburg, Ohio. The atomic isotope composition was 95.6% 12C,4.4% 13C. and 6.0% 32S 1.7% 33S, 90.6% 34S, 1.6% 36S; and the molecular composition included 8 1% ‘2C3’S2, 9% ‘2C32S34S,and 0.4% ‘*C3*S2. RESULTS
AND DISCUSSION
Vibrational and Rotational Assignments Table I lists the wavelengths in air and the vacuum wavenumbers of the prominent bandheads in the absorption spectrum of ‘2C34S2.The vibrational assignments were, for the most part, based upon those of Kleman (3). The bands exhibit isotope shifts ranging from 15 to 40 cm-’ to the red of the normal isotope, and the appearance of the rotational structure of a given band was usually sufficient to establish the value of Kb. In addition, the rotational constants of the Z bands allowed unambiguous identification of the lower vibrational state whenever rotational analysis was possible. Intensities were also found generally to follow the observations of Kleman. Since the ground state vibrational constants for u2and 3u2are not available, the rotational analysis
277
‘2C34SzUV SPECTRUM TABLE I Assignments of Prominent Bandheads in the a3A2-X’Z, Band System of C34S2
x/n 3363.9765 3374.2237 3393.4636 3398.9804 3404.0928 3410.2339 3412.7886 3393.4636 3423.6177 3441.6726 3455.7316 3463.7546 3470.4823 3470.6383 3473.3293 3487.9545 3494.3424 3502.5724 3502.7203 3505.7348 3511.4539 3511.4983 3516.2920 3522.0775 3522.5913 3524.0622 3527.6213 3527.7026 3527.1918 3533.8043 3539.4686 3542.4493 3543.1764 3547.7124 3549.4439 3553.7372 3553.9645 3554.7719 3555.0533 3555.2451 3562.1721 3563.4347 3572.4296 3575.0517 3576.5461 3576.7409 3579.1237 3581.3984 3582.3295 35813.6430 3588.8954 3590.5666 3594.5535 3602.0884 3606.7582 3613.2779 3613.7521
v/cm-l 29718.2 29627.9 29459.9 29412.1 29368.0 29315.1 29293.1 29460.0 29200.5 29047.3 28929.1 28862.1 28806.1 28804.9 28782.6 28661.9 28609.5 28542.3 28541.1 28516.5 28470.1 28469.7 28430.9 28384.2 28380.1 28368.2 28339.6 28339.0 28343.1 28290.0 28244.8 28221.0 28215.2 28179.1 28165.4 28131.4 28129.6 28123.2 28121.0 28119.4 28064.7 28054.8 27984.2 27963.6 27952.0 27950.4 27931.8 27914.1 27906.8 27057.7 27855.8 27842.8 27811.9 27753.8 27717.8 27667.8 27664.2
h/A
assignment
(0.6.2) - (0.0.0) G"5 2) - (O,O,O) 4; ; 3u - (0.0.0) r
&.O)(0.5.2) (0.4.2) (O.lO,O)(Of3.2) (1.7.0) (0,4,2) (0,482) (0,9.0) (0,5.2) (0,10.0)(0~3.2) (0.3,2) (0.8.0) (1.7.0) (1.7.0) (0.4.2) (0.9,O) (0,9.0) -
(0;o.o)
e
(0.0.0) (0.0.0) (0.0.0) (0,O.O) (O,O,O) (0,l.O) (0.1.0) (0.0.0) (0.2.0) (0.1.0) (O,l,O) (0.1.0) (0.0.0) (0.1.0) (O,l,O) (0.2.0) (0,l.O) (0,l.O)
z E E z z n n E h II? II n z n n A ll II
(0,o:o) E
(0.1.2) - (0,O.O) I: (1.5.0) - (0.0.0) z (1,E.O) (0,7,0) (1.6,0) (1.6,O) (0,3,2)
-
(0.2.0) (0,O.O) (0.1.0) (0.1.0) (0.2.0)
XI I II? n? A
(0.3.2) - (0,Z.O) z (0.8,O) - (0.1.0) II? (0.8.0) - (0.1.0) li? (1,7.0) (1.4.0) (0.9,O) (0.6,o) (1.5.0) (1.5.0)
-
(0.2.0) (0.0.0) (0.2.0) (0,O.O) (0,l.O) (0,l.O)
2 c E E n n
(0.2,2) (0.7,O) (0,7,0) (l-6,0) (1.6.0) (0.8.0) (0.8.0) (1.4.0) (1,4,0)
-
(0,2.0) (0.1.0) (0,l.O) (0,2,0) (0.2.0) (0.2.0) (0.2.0) (0,l.O) (0.1.0)
A n n A? E? A z n II
3615.9303 3625.0878 3625.2706 3625.4442 3629.8251 3629.9033 3630.4808 3635.7143 3637.1978 3637.2116 3638.3482 3642.3707 3646.5900 3647.9946 3650.3546 3651.8008 3652.3482 3658.0576 3663.0807 3663.2031 3663.4875 3667.8366 3673.6951 3674.8196 3680.0950 3682.7440 3683.0183 3683.3031 3684.7408 3684.7932 3685.1925 3685.7024 3686.3024 3689.9570 3695.6125 3695.9269 3698.6415 3702.7118 3703.0167 3703.0769 3703.1241 3707.6174 3712.6896 3714.1848 3714.2104 3719.1943 3721.7438 3723.8974 3734.2591 3734.7881 3735.4970 3740.3246 3748.2193 3753.5706 3754.0066 3755.2003 3759.1611
v/cm-l 27647.5 27577.7 27576.3 27575.0 27541.7 27541.1 27536.7 27497.1 27485.9 27485.8 27477.2 27446.8 27415.1 27404.5 27386.8 27375.9 27371.8 27323.2 27291.7 27290.7 27288.6 27256.3 27212.8 27204.5 27165.5 27145.9 27143.9 27141.R 27131.2 27130.8 27127.9 27124.1 27119.7 27092.9 27051.4 27049.1 27029.3 26999.5 26997.3 26996.9 26996.5 26963.8 26927.0 26916.2 26916.0 26879.9 26861.5 26846.0 26771.5 26767.7 26762.6 26728.0 26671.8 26633.7 26630.6 26622.2 26594.1
assignment (0,6,0) (1,5,0) (0,6,0) (0.1.2) (1.5.0)
- 0,l.O) n - 0.2.0) A - '0.1.0) " - 0,2.0) z - 0.2.0) z
(1.6.0) (0.7.0) (0.7.0) (0,2,2) (0.7.0) (1.6.0) (0.8.0) (0,4,0) (1.3.0)
- '0.3.0) m - 0.2.0) A - '0.2,O) A - 0.3.0) n - 0.2.0) L - 0.3.0) n - 0.3.0) m - 0.0.0) L - O.l,O) n
(O.E,O) (0.5,0) (1.4,o) (0.5,O) (1.4,O) (1.5,O) (0.6,0) (0.6,O) (1,5,0) (1,5.0)
-
(0.3,O) (0,l.O) (0.2.0) (O.l,O) (0.2.0) (0.3.0) (0.2.0) (0,2,0) (0,3.0) (0.3,O)
II n A II I: m A c II II
(0#7,0) - (0.3.0) 0 (0.7,O) - (0.3.0) m
(0.2.2) (0,7,0) (0,7.0) (lf6.0) (0.4.0) (0.4,O) (1.3.0) (1.3.0) (1.3,O) (1.4.0) (0,5.0) (0.5,o) (O-5,0) (1.4.0) (0.6.0) (0.6,0) (0.6.0) (1,5.0) (1.5.0) (0.7.0) (0.7.0) (1.3,O) (0.4.0)
-
(0.4,0) (0,3,0) (0,3.0) (Oe4.0) (0.1.0) (0.1.0) (0.2.0) (0.2.0) (0.2,O) (0.3.0) (0.2,0) (0.2,O) (0.2.0) (0.3.0) (0,3.0) (0,3.0) (0,3.0) (0.4,O) (0;4.0) (0.4.0) (0,4.0) (0,3,0) (0.2.0)
A n n A n n A A L 0 A A h n $ n n A c A z 8 A
of IT and higher-K bands would not be profitable at this time. Without these lower state constants, determination of the rotational constants A, for the excited electronic state is not possible. Since the isotope shifts of bandheads are critically dependent on both the change in the vibrational energy and the change in the rotational constant between the isotopic species, the bandhead positions cannot be used in a straightforward way to refine the molecular Hamiltonian. The Z bands were, therefore, rotationally analyzed to determine the vibrational band origins and effective values of the B rotational constants,
HARDWICK
278
AND SELISKAR
TABLE I-Continued
3759.9526
3762.0248 3762.6611 3764.8269 3164.8472 3114.5992 3775.1978 3775.8278 3780.7763 3788.1712 3793.7240 3797.7441 3799.7901 3802.2967 3805.3963 3807.4440 3811.1062 3811.2720 3815.2047 3816.6903 3817.2813 3818.2054 3820.8917 3823.0606 3829.1885 3829.5163
26588.5 26573.9 26569.4 26554.1 26554.0 26485.4 26481.2 26476.7 26442.1 26390.5 26351.8 26323.9 26309.8 26292.4 26271.0 26256.9 26231.7 26230.5 26203.5 26193.3 26189.2 26182.9 26164.5
(0.4.01 1;3;oj 1,3.0) 0,5,0) 0,5,0) 0,5.0) 0.5.0) 1,4,0) 1,4.0) 0,6.0) 0.6.0) 0.3.0) 0,7,0) 0.3.01 l-2,0) 0,4.0) 0.7.0) 0,7.0) 0.5.0) 0.4.0) 0.4.0) 1.3,O)
-
(0.2.0) io;3;oi (0.3.0) (0.3.0) (0,3,0) (0.3,0) (0.3.0) (0,4.0) (0.4.0) (0,4,0) (0.4.0) (0.2.0) (0,5,0) (0.2.0) (0,3,0) (0.3.0) (0.5.0) (0.5.0) (0.4.0) (0.3.0) (0.3.0) (0.4.0)
z
h
m E II
m n I1 I-
n n b
(1.3.0) - (0,4.0) E ;;a;;.; 26105:6
(1.4.0) - (0.5.0) Q
3829.9361 3830.0325 3830.0746 3835.2992 3838.8933 3841.3969 3846.1795 3851.5500 3852.2061 3854.3937 3859.5197 3860.4142 3861.0149 3865.3700 3873.4633 3873.6667 3873.7181 3878.6723 3882.5060 3884.9995 3895.1541 3918.9520 3919.0145 3923.7608 3930.3898 3939.9962
26102.7 26102.0 26101.7 26066.2 26041.8 26024.8 25992.5 25956.2 25951.8 25937.1 25902.6 25896.6 25892.6 25863.4 25809.4 25808.0 25807.7 25774.7 25749.3 25732.7 25665.7 25509.8 25509.4 25478.5 25435.6 25373.6
(0,5.0) - (0.4.0) n (0,5#0) - (0,4.0) A (0.5,O) - (0.4,O) E (Oe6.0) - (0,5,0) m (0.6.0) - (0.5.0) n (0,4.0) - (0.4.0) r (1.3,0) (1,3,0) (0.4.0) (0.4,0) (0.4.0) (1,3.0) (0.5.0) (0,5.0) (0.3,0)
-
(0,S.O) (0,5,0) (0.4.0) (0.4,0) (0,4.0) (O.S,O) (0.5.0) (O.S,O) (0.4.0)
H m A A z II m n b
(0.3.0) - (0,4,0) z (0.4.0) - (0,5.0) @
each of which is essential to an adequate development of a molecular potential function. The observed line positions for these bands are presented in Table II. Constants for the ground vibrational level of the lower electronic state were held fixed at the values determined from the infrared spectra of Blanquet et al. (11-13). The vibrational and rotational constants for the (0, 2,O)” state were determined from a combination of infrared data (II) and the present ultraviolet measurements. The constants for (0, 4, 0)” were determined from the ultraviolet data alone. Since the rotational structure of the excited vibronic states is perturbed, determination of the ground state vibrational and rotational constants was accomplished by simultaneously fitting all vibrational and rotational combination differences which could be obtained from differences of the measured line positions. The constants thus obtained are presented in Table III. These were held fixed in subsequent simultaneous fittings of the line positions of several bands in order to determine the term values and rotational constants of the upper electronic state. These constants are presented in Table IV. The calculated line positions and residuals of Table II were computed using these constants. The bands at 293 15 and 29368 cm-’ arise from the ground vibrational level of the lower electronic state, but the upper vibronic state has no obvious and unambiguous assignment. They are designated as 1U and 3U by analogy with nearby bands in Kleman’s spectrum, although it should be emphasized that the vibrational state need not be the same as that of the bands in the normal isotope bearing the same labels. The rotational constants, intensity, and isotope shifts suggest that these are higher vibrational states of the R system. Perturbations Even at low vibrational quantum numbers, the vibrational spacing is somewhat irregular, and the vibrational energies cannot be represented by a rapidly converging
TABLE II Rotational Assignments for the Cold Z Bands of the a’& Electronic State of C34Sz(All line positions are in cm-‘. Complete assignments of the hot Z bands are available from the journal or the authors on request.)
(0,6.0)
(0.4.0) - (O,O,O) J
PIJ) obs
14 16 18 20 22 24 26 28 30 32 34 36 38 head
R(J) o-c
27388.894 27388.648 27388.384 27388.147 27387.890 27387.702 27387.533 27387.366
-0.035 -0.008 -0.017 -0.018 -0.058 -0.048 -0.036 -0.041
27387.089 27387.021
-0.048 -0.008
27386.73
obs
-0.002 -0.025 -0.014 -0.001
27399.351 27400.036 27400.758 27401.500 27402.248 27403.007
-0.030 -0.040 -0.031 -0.019 -0.013 -0.025
-0.01
obs 16 18 20 22 24 26 28 30 32 34 36 38 40 head
27965.207 27964.996 27964.762 27964.610 27964.365
27963.60
(0,5,0) - (O,O,O) P(J)
J
obs 4 6 8 10 12 14 16 18 20 24 26 28 30 32 36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 66 68 70 72
27680.511 27680.289 27680.048 27679.755
-0.096 -0.026 0.007 -0.032
obs
J o-c
27683.750 27684.398 27684.806 27685.305 27685.804 27686.410 27686.931 27687.538 27688.157 27689.403 27690.075 27690.768 27691.468 27692.218 27693.537 27694.368 27695.134 27695.948 27696.765
27697.622 27698.467 27699.334 27700.211 27701.139 27702.042 27702.950 27703.899 27704.822 27705.836 27706.791 27707.804 27708.792 27709.809
-0.106 0.069 -0.014 -0.026 -0.057 0.001 -0.045 -0.024 -0.010 -0.028 -0.015 0.000 0.005 0.041 -0.119 -0.053 -0.069 -0.055 -0.054 -0.029 -0.032 -0.029 -0.032 0.001 -0.006 -0.023 -0.013 -0.044 0.003 -0.023 -0.004 -0.022 -0.024
14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 head
6 8 10 12 14
o-c
27966.441
-0.012
27965.853 27965.513
0.030 -0.025
o-c
27972.219 27972.738 27973.462 27974.057 27974.713 27975.412 27976.084 27976.766 27977.454 27978.268 27979.030 27979.823 27980.617
0.001 -0.076 0.032 -0.009 -0.007 0.018 -0.002 -0.031 -0.072 -0.006 -0.009 0.001 -0.006
0.02
obs
-0.019 -0.021 -0.026
27971.619
-0.022
28244.76
J
0.079 0.061 0.047
obs
o-c
28251.914 28252.532 28253.203 28253.899 28254.598 28255.340 28256.088 28256.850 28251.646 28258.417 28259.269 28260.049 28260.953 28261.817 28262.733 28263.648 28264.605 28265.571 28266.559
0.057 0.029 0.030 0.032 0.015 0.021 0.012 -0.001 0.002 -0.037 -0.011 -0.073 -0.027 -0.037 -0.011 -0.005 0.023 0.045 0.051
0.07
P(J) obs
2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36
0-c
27969.515 27970.010 27970.522
28245.569 28245.375 28245.209
R(J) 0-c
(o.8,o) - (o,o,o)
R(J)
P(J) obs
0.013 -0.033 -0.042 0.012 -0.047
obs
P(J) obs
(0.6,0) - (o,O,o) J
R(J) o-c
(0,7,0) - (O,O,O) R(J)
o-c
l0.0.0)
P(J)
J
o-c
27396.174 27396.156 27397.389 27398.043
-
279
28520.779 28520.386 28520.012 28519.682 28519.352 28519.043 28518.758 28518.504 28518.249 28518.027 28517.813 28517.632 28517.453 28517.295 28517.142
R(J) o-c
0.011 0.003 -0.007 0.007 0.000 -0.006 -0.008 0.002 -0.009 -0.005 -0.012 -0.004 -0.011 -0.015 -0.029
obs 28521.829 28522.270 28522.755 28523.240 28523.772 28524.305 28524.868 28525.435 28526.041 28526.652 28521.282 28527.936 28528.593 28529.279 28529.993 28530.700 28531.429 28532.174
0-c 0.008 -0.009 -0.002 -0.015 -0.001 -0.007 -0.002 -0.012 -0.002 -0.005 -0.008 -0.003 -0.013 -0.010 0.005 -0.002 -0.001 0.002
280
HARDWICK
AND SELISKAR
TABLE II-Continued (0,8,0)
J
(O,O,O)
-
38 40 42 44 46 48 head 52 54 56
28516.50
obs
0-c
28532.919 28533.678 28534.476 28535.267 28536.063 28536.878 28537.700 28538.534 28539.352 28540.196
-0.06
(0,9,0)
J
2 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 head 50 52
28782.60
J
(O,O,O)
obs
-0.03
-
0-c
28787.836 28788.758 28789.273 28789.790 28790.317 28790.874
0.032 0.021 0.039 0.039 0.030 0.031
28791.457 28792.040 28792.670
0.038 0.026 0.043
28793.283 28793.944 28794.614 28795.300 28796.010 28796.712 28797.426 28798.194 28798.952 28799.736 28800.537 28801.347 28802.153 28802.944 28803.826 28804.686
0.024 0.034 0.036 0.037 0.044 0.027 0.007 0.024 0.017 0.021 0.029 0.033 0.020 -0.019 0.022 0.030
(O,O,O)
P(J) obs
-0.009 -0.018 0.000 0.000 -0.007 -0.004 -0.005 -0.003 -0.025 -0.030
R(J) 0-c
29051.843
-0.010
29051.138 29050.789 29050.438 29050.062 29049.760 29049.441 29049.147 29048.864 29048.658 29048.428 29048.199 29048.041 29047.863 29047.702 29047.574 29047.421
0.049 0.057 0.047 -0.005 0.001 -0.026 -0.044 -0.068 -0.031 -0.033 -0.051 -0.014 -0.012 -0.009 0.011 -0.009
obs
29052.598 29052.997 29053.394 29053.843 29054.324 29054.811 29055.321 29055.809 29056.357 29056.877 29057.477 29058.048 29058.705 29059.323 29059.960 29060.632 29061.327 29062.046 29062.816
0-c
0.129 0.096 0.045 0.030 0.030 0.020 0.016 -0.026 -0.024 -0.066 -0.044 -0.067 -0.020 -0.028 -0.033 -0.018 0.004 0.034 0.100
-
(O,O,O)
P(J)
R(J)
obs
0-c
R(J) 0-c
(0.10.0~
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36
-
P(J) obs
J
R(J)
P(J) obs
(O,lO,O)
38 40 42 44 46 48 head 52 54 56 58 60 62 64 66 68 70 72 74 76 78
0-c
29047.055 29046.90
0.054
4 6 8 10 12 14 16 18 20 22 24 26
-
29296.358 29296.037 29295.733 29295.452 29295.174 29294.938 29294.708 29294.491 29294.307 29294.034
R(J) 0-c
29297.068
obs
0.003 0.007 0.008 0.012 0.000 0.011 0.010 0.003 0.012 -0.085
(1,4.0)
4 6 8 10 12 14 16 18
29298.483
-0.020
29299.442 29299.928 29300.438 29300.985 29301.537 29302.116 29302.714 29303.325 29303.965 29304.587 29305.283 29305.932 29306.626 29307.352 29308.043 29308.784 29309.534 29310.285 29311.070 29311.823 29312.604 29313.432 29314.176
0.006 -0.005 -0.012 -0.001 -0.005 0.000 0.005 0.005 0.016 -0.007 0.027 -0.002 -0.001 0.018 -0.011 -0.004 0.001 -0.004 0.015 -0.007 -0.008 0.030 -0.020
-
(O,O,O)
P(J) obs
28057.925 28057.618 28057.306 28057.009 28056.742 28056.490
0-c
0.003
LO 30 32 34 36 38 40 42 44 46 48 5"
J
0.101 0.167 0.200 0.040 -0.035 -0.029 -0.028 -0.078 -0.123 -0.141 -0.136 -0.061 0.018 0.043 0.062 0.097 0.096 0.018 0.029 -0.068 -0.039
fn.n.01 ,~.~,~,
P(J) obs
0-c
29063.536 29064.337 29065.121 29065.727 29066.434 29067.237 29068.052 29068.832 29069.633 29070.478 29071.363 29072.336 29073.330 29074.289 29075.262 29076.270 29077.263 29078.201 29079.251 29080.216 29081.333
-0.04
cn.11.n) .~.~~.
J
obs
R(J) 0-c
-0.030 -0.007 -0.007 -0.011 -0.004 0.000
obs
28060.603 28061.024 28061.505 28062.051 28062.566 28063.128 28063.674 28064.262
0-c
0.039 -0.013 -0.023 0.013 -0.001 0.014 -0.005 -0.001
281
“C3?S2 UV SPECTRUM TABLE II-Continued
(1,4,0) - (O,O,O) .J
20 22 24 26 28 30 32 34 36 head
R(J)
P(J) obs
o-c
28056.248 28056.015 28055.824 28055.646 28055.482 28055.331 28055.201 28055.072 28054.981 28054.8
(1,7,0) - (O,O,O)
-0.004 -O.OiE -0.007 -0.001 0.002 0.001 0.003 -0.010 -0.001 0.1
J
P(J)
o-c
obs 28064.880 28065.489 28066.117
0.015 0.004 -0.005
28067.418
-0.030
28068.839
-0.003
obs 50
52 54 56 58 60
28872.126 28873.030 28873.936 28874.883 28875.818 28876.736
J
8 10 12 14 16 18 20 22 24 26 28 30 head 34 36 38 40
28339.807 28339.613
28339.0
o-c
-0.040 -0.022
0.2
o-c
obs 28344.300 28344.849 28345.427 28346.033 28346.660 28347.327 28348.042 28348.740 28349.475 28350.208 28350.995 28351.830 28352.657 28353.556 28354.402 28355.280 28356.193
0.044 0.038 0.033 0.030 0.022 0.027 0.055 0.041 0.039 0.011 0.014 0.041 0.039 0.087 0.062 0.049 0.052
(1,7,0) - (O.O,O) J
P(J) obs
12 14 16 18 20 22 24 26 28 30 24 26 28 30 32 34 36 38 40 38 40 42 44 46 48
28862.139 28862.358 28862.545 28862.771 28862.978 28863.168 28863.304 28864.459 28864.793
28865.104 28865.518 28866.026 28866.548 28867.101 28867.642 28868.125 28868.865 28869.586 28870.375 28871.281
R(J) o-c
-0.886 -0.853 -0.912 -0.991 -1.145 -1.371 -1.705 0.336 0.254 0.095 -0.012 -0.073 -0.167 -0.275 -0.436 0.047 0.046 -0.010 -0.031 0.035
o-c
28894.187 28895.918 28897.679 28899.451 28901.175
0.037 0.039 0.055 0.070 0.030
obs
o-c
28867.642 28868.506 28869.428 28870.375 28871.395 28872.426 28873.465 28874.486 28875.431 28876.303
-0.741 -0.761 -0.786 -0.847 -0.895 -0.990 -1.133 -1.350 -1.696 -2.166
28874.883 28876.099 28877.238 28878.474 28879.777 28881.136 28882.498 28883.834
0.285 0.263 0.111 0.005 -0.083 -0.161 -0.28( -0.468
28884.394 28885.917 28887.457 28889.039 28890.786 28892.455
0.092 0.053 -0.004 -0.053 0.033 0.015
head 38 40 42
R(J)
P(J) o-c
obs R(J)
P(J) obs
0.014 0.02R 0.025 0.048 0.046 0.019
obs
(0,1,2) - (0.0.0)
(1,5,0) - (0,O.O) J
R(J) o-c
28339.60
0.01
obs
o-c
28355.013 28355.884 28356.833 28357.636
0.012 0.033 0.108 0.013
(0,3,2) - (O,O,O) J
P(J) obs
2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 40 42 44 46 48 50 52 54 56 58
R(J)
o-c
28931.302 28930.940 28930.640 28930.370 28930.116 28929.894 28929.703 28929.539
0.019 -0.002 0.008 0.017 0.012 0.010 0.009 0.007
28929.15
0.02
obs
o-c
28932.696
-0.025 -0.011 -0.016 -0.006 -0.002 -0.001 0.000 0.009 0.002 0.005 0.007 -0.009 -0.011 -0.018 -0.005 -0.002 -0.015 -0.016 -0.012 -0.004 -0.018 0.011 0.011 0.027 -0.023
28933.191 28933.698 28934.250 28934.826 28935.429 28936.061 28936.730 28937.410 28938.128 28938.871 28939.621 28940.411 28941.221 28942.074 28946.630 28947.598 28948.604 28949.641 28950.710 28951.787 28952.940 28954.106 28955.315 28956.508
(0,4,2) - (O.O,O) J
8 10 12 14 16 18 20 22 24 head
R(J)
P(J) obs
o-c
29201.356 29201.109 29200.907 29200.746 29200.666
0.041 0.012 -0.003 -0.011 0.029
29200.50
0.01
obs 29205.411 29206.009 29206.683 29207.295 29207.960 29208.638 29209.372 29210.142 29210.952 29211.808
o-c -0.057 -0.031 0.040 0.017 0.014 -0.010 -0.011 -0.012 -0.009 0.003
HARDWICK
282
AND SELISKAR
TABLE II-Continued (0,4,21 J
-
C0,O.O)
P(J) obs
1u - (0,O.O) J
R(J) 0-c
28 30 32 34
obs
29212.663 29213.633 29214.594 29215.558
-0.024 0.024 0.023 -0.017
(0,5,2) - (0.0.0) J
P(J) obs
8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 head 42 44 46 48 50 52 54 56 58
R(J) 0-c
obs
o-c
29466.255
29462.326 29462.051 29461.742 29461.371 29461.121 29460.960 29460.747 29460.559
0.025 0.006 -0.094 -0.094 -0.024 -0.027 -0.026
29459.83
-0.02
-0.010
29466.771 29467.247 29467.822 29468.402 29468.980 29469.591 29470.216 29470.878 29471.544 29472.244 29472.956 29473.684 29474.429 29475.242 29476.032
29476.878 29477.723 29478.672 29479.565 29480.540 29481.456 29482.466 29483.429 29484.561 29485.547
0.017 0.021 -0.035 -0.011 -0.002 -0.015 -0.016 -0.023 -0.014 -0.022 -0.017 -0.023 -0.035 -0.052 -0.025 -0.044 -0.031 -0.044 0.021 0.006 0.045 -0.001 0.020 -0.035 0.050 -0.041
P(J) obs
o-c 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 head 42 44 46 48 50 52 54 56 58 60 62 64 66 68 70 72 74
29316.835 29316.586 29316.308 29316.096 29315.911 29315.723
29315.1
R(J) o-c
-0.004 0.016 -0.015 -0.003 0.015 0.008
0.1
obs
o-c
29321.574 29322.119 29322.678 29323.293 29323.911 29324.533 29325.209 29325.898 29326.591 29327.316 29328.068 29328.831 29329.620 29330.410 29331.226 29332.077 29332.932 29333.795 29334.692 29335.597 29336.514 29337.455 29338.403 29339.389 29340.359 29341.348 29342.332 29343.361 29344.370 29345.404 29346.407 29347.449 29348.523
0.011 0.003 -0.013 0.005 0.004 -0.014 0.000 0.006 -0.005 -0.005 0.003 0.001 0.007 -0.006 -0.011 0.001 -0.001 -0.011 -0.004 -0.005 -0.010 -0.004 -0.006 0.017 0.011 0.012 -0.003 0.017 0.007 0.013 -0.019 -0.020 0.005
3u - (O,O,O) J
P(J) obs
R(J) o-c
ohs
0-c
(0.6,2) - (O,O,O) PIJ)
J
obs 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 head
RIJ) o-c
29722.289 29721.894 29721.539 29721.257 29720.877 29720.653 29720.325 29720.050 29719.811 29719.582 29719.387
-0.010 -0.032 -0.031 0.027 -0.031 0.051 0.011 0.007 0.022 0.030 0.053
29718.943 29718.796 29718.650 29718.489 29718.354
-0.007 0.011 0.011 -0.023 -0.049
29718.20
0.05
obs
o-c
29723.701 29724.180 29724.593 29725.130 29725.620 29726.192 29726.720 29727.261 29727.808 29728.392 29729.023
-0.036 -0.006 -0.058 -0.003 -0.012 0.044 0.038 0.029 0.008 0.007 0.035
29730.249 29730.892 29731.572 29732.261 29732.951 29733.673 29734.404 29735.291 29736.087
0.002 -0.011 -0.006 -0.011 -0.034 -0.043 -0.063 0.053 0.058
2 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 head
29372.272
29370.403 29370.130 29369.842 29369.554 29369.296 29369.065 29368.848 29368.665 29368.503 29368.365
29367.95
-0.043 0.012 0.027 0.017 0.012 0.011 0.001 0.001 0.001 0.003
0.06
29373.196 29373.721 29374.251 29374.807 29375.428 29376.005 29376.695 29377.340 29378.013 29378.710 29379.428 29380.199 29380.931 29381.683 29382.502 29383.298 29384.112
0.034 -0.004 0.003 -0.011 -0.023 0.006 -0.032 0.021 0.006 -0.002 -0.007 -0.010 0.022 -0.003 -0.024 0.006 0.001 0.000
283
“C”Sz UV SPECTRUM TABLE III
Vibrational and Rotational Constants for the Ground Electronic State of C34S2(Uncertainties are given as one standard deviation in units of the last significant digit.)
iO,O,Of
0.1027111=
0.984a
(O.Z,O)
797.363(l)
0.1030664(6)
0.941(7)
(0,4.0)
1609.869(5)
0.1033707(3)
0.900"
a.
From
b.
Fixed.
Ref.
(11).
TABLE IV Effective Vibrational and Rotational Constants for the Z Levels of the o3Az Electronic State of C’%> (Vl,V2,V3)
T,'/Crn
-1 RV
a/cm-l
D,'/lo-8c,-1
H eff'/10-12cm-1
(0.3.0)
27095.355
0.105000(21)
2.28(93)
(0.4.0)
27391.367
0.105095(11)
3.72(25)
(O,5*0)
27682.754
0.105092(9)
3.60(18)
(0,6,0)
27967.954
0.105245(6)
4.85(Y)
(O.7,0)
28247.892
0.106493(32)
44.7(24)
64.2(46)
(0,8.0)
28521.167
0.105304(30)
14.3(20)
67.2(35)
(0,9.0)
28787.159
0.105248(21)
(O,lO,O)
29052.260
0.104775(25)
10,11.01
29297.457
0.105256(35)
(1,3.0)
27768.675
0.104669(17)
(1.4,O)
28059.466
0.105083(7)
(1.5.0)
2fl342.095
0.106181(7)
12.7(l)
(1.7.0)
28R64.21a
0.111034
38.
(0.1.2)
28343.4(2Jh
0.105540(30)
(0.3.2)
28932.058
0.106614(44)
(o.4,2)
29203.328
0.106489(121)
8.95(63) 3.771110)
3.92(66) 5.97(15)
0. 27.2(33)
29464.174
0.105102(20)
-5.7(6)
(o.6,2)
29723.096
0.104804(34)
-3.0(20)
29318.928
0.105567(15)
'I3U"
29371.583
0.105914(26)
a.
Severely
perturbed
band:
constants
41.3(64)
-21.0(89)
(0.5.2)
'I1U"
39.(12)
13.4(14)
7.39(28) 20.6(17)
are
estimates.
b. Fragmentary band.
Uncertainties are given as one standard deviation in units of the last significant digit. Rotational and distortion constants without stated uncertainties were held fixed during the calculation. The errors on vibrational term values are believed to be dominated by systematic errors of measurement amounting to about 0.05 cm-‘, except as stated.
284
HARDWICK
AND SELISKAR
Taylor series in the vibrational quantum numbers. This irregularity can be ascribed to vibrational perturbations within the a3A2 state, although the vibrational frequencies of the upper state are so poorly known that the identity of the perturbing state is usually ambiguous. As with the normal isotope, the bands of r2C34S2are rotationally well-behaved near the system origin and become progressively irregular with increasing vibrational energy in the upper state. This irregularity is exhibited both in the rotational constants of those states and in the often severe perturbations to the rotational fine structure. Figure 1 shows an example of the contrast to be found between Z bands which are regular and well-behaved and those which are strongly perturbed. The (0, 6, 0) state, as illustrated by Fig. 1, is largely a well-behaved band, having only a single perturbation at J’ = 6 1 to the observed rotational structure. The ( 1, 7, 0) state, on the other hand, is marked by at least three important avoided crossings, giving rise to bands with a highly irregular appearance. This contrast is also evident from a comparison of the residuals of bands arising from the (0,6,0) and (1,7,0) states in Table II. The residuals of the bands having ( 1, 7,0) as the upper state are substantially in excess of either the experimental error or the error in the ground state combination differences. The (1, 5, 0) level of the upper electronic state (T = 28342.1 cm-‘) is found to be in accidental resonance with a vibronic level which does not appear in Kleman’s spectra of the normal isotope (T = 28343.4 cm-‘). The rotational levels of the two states do not actually cross, but the perturbing band steals enough intensity for a rotational analysis of the band fragments to be possible. On examination, the vibronic origin is found to be approximately one quantum of u; lower in energy than the band designated ‘S’ by Kleman. Kleman’s S band has been assigned by Jungen and Merer (10) to be the (0, 2, 2) band of the R system; we therefore assign the state at 28343.4 cm-’ as the (0, 1, 2) level, although the (3, 0, 0) state cannot positively be excluded.
60
50
40
50
FIG. I. Two representative Z-type bands in the near-ultraviolet spectrum of ‘2C34S2.The (0, 6, 0) band (upper trace) exhibits only a slight irregularity at J’ = 61. while the (1, 7, 0) band (lower trace) suffers from several major perturbations.
‘2C%2 UV SPECTRUM
285
CONCLUSIONS
The near-ultraviolet absorption bands of ‘2C34S2have been measured at high resolution over the region 3900-3350 A. The vibrational and rotational analyses of the Z bands of the Kleman R system have been performed, and the derived constants for the upper and lower electronic states are reported. The R system of the heavy sulfur34 isotope is similar to that of the sulfur-32 isotope in that both show well-behaved bands at low vibrational levels of the B2spin-electronic state which suffer progressively more serious perturbations with increasing vibrational quantum number. The origins of these perturbations are not completely specified, but we can find no conclusive evidence which would implicate a second electronic state as being responsible. The isotope shifts found for the Kleman S bands are large and regular, consistent with the hypothesis of Merer and Jungen (IO) that these bands are derived from excited stretching vibrations of the R system. The 1U and 3 U bands of the heavy isotope appear to be well-behaved, although further work will be necessary before these and higher members of the U progression are positively identified. ACKNOWLEDGMENTS The authors are indebted to Dr. A. J. Merer for communicating the results of his analysis prior to publication. The authors are also grateful to Mr. C. Kinard, Monsanto Research Corporation, for his technical assistance in recording the spectra. The multiple-reflection cell used in this work was based on a design developed at the National Research Council of Canada and kindly provided to the authors by Dr. D. A. Ramsay. This work was supported by the Office of Basic Energy Sciences of the United States Department of Energy. This is Document Number NDRL-2689 from the Notre Dame Radiation Laboratory. RECEIVED:
March 14, 1985 REFERENCES
L. N. LIEBERMANN,Phys. Rev. 60,496-505 (1941). R. S. MULLIKEN,Phys. Rev. 60, 506-513 (1941). B. KLEMAN, Canad. J. Phys. 41,2034-2063 (1963). A. E. DOUGLASAND E. R. V. MILTON, J. Chem. Phyx 41,357-362 (1964). J. T. HOUGEN, J. Chem. Phys. 41, 363-366 (1964). R. M. H~CHSTRASSER AND D. A. WIERSMA,J. Chem. Phys. 54,4 165-4169 (197 I). CH. JUNGEN, D. N. MALM, AND A. J. MERER, Canad. J. Phyx 51, 147 I- 1490 (1973). K.-E. HALLIN, D. N. MALM, AND A. J. MERER, J. Mol. Spectrosc. 54, 318-327 (1975). CH. JUNGEN, D. N. MALM, AND A. J. MERER, Chem. Phys. Lett. 16,302-305 (I 972). A. J. MERERAND CH. JUNGEN,private communication. G. BLANQUET,J. WALRAND, AND C. P. COURTOY,Ann. Sot. Sri. Bruxelles 92,205-221 (1978). J. WALRAND, G. BLANQUET,AND C. P. COURTOY,Ann. Sot. Sci. Bruxelles 93,2 1 l-225 ( 1979). G. BLANQUET,J. WALRAND, AND C. P. COURTOY,J. Mol. Spectrosc. 72, 227-237 (1978). 14. J. L. HARDWICKAND W. J. LAFFERTY.1. Mol. Spectrosc. 100, 358-367 (1983).
I. 2. 3. 4. 5. 6. 7. 8. 9. 10. II. 12. 13.