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The band spectrum of the InH molecule: Characterization of the a3Π state
The Band Spectrum
of the InH Molecule: of the a3n State
Characterization
*In est.ensive emission spectrum of InH, in the regicbn 1500-8000 9, has bwn obtained from a King furnace containing indium mrtal :tnd hydrogen at tenperatures greater than 1500°C. Txenby bands srising from the rr3IIo+,,+ T’S’ trxwitions h:tve been measured and nnalyzed. ()I these. thirteen had IJeen previously reported, but extensions 2nd revisions were found necessary fIl1 the interpretation of predissociation phenomens. Two previously unrep~~rte~l b:tnds hxve heen analyzed 9s the 10-O) and (1 1) bands of the trunsition u~II~T~-.Y%+. The position of the “n2d- cclmponent indiwtes t.hnt. the ~~11 st:Lte is close to Cnse c. The predissociations of the 311,=. 311, 1, and sII~,+ st:tttr II:LVC been characterized and the somewhat :rnonwlous results discuss4 it1 det.ail. I. INTKOI~L~CTIO?r
In recent years the spectrum of the InH molecule has been extensively studied. In 1938 GrundstrGm (1, 2) observed a molecular spectrL,,n in emission from a high pressure dc arc (about 7 atm of hydrogen gas) between electrodes of carhou and indium. He performed rotational analyses on twel\;r bands in the region 0 *2-\‘ and ‘II-3 of IuH, and X30-72.50 A, which he assigned to two transitions noted that t,he intensity of the spectrum was pressure dependent, the bands 20 mm Hg and showing appreciable being unobservable at approximately intensity only for pressures of approximately out’ atmosphere or greater. III addition, he pointed out that the ‘n-2 hauds broke off sharply, indicating a predissociation, and that the Q branch broke off at lower energy than the f’ aud R branches. Unfortunately, he did not report. his original data, hut list.4 only the calculated rot,ational term vahw~, a fact which has caused a great deal of additional labor in the present work. Kleman (J) examined the existing data ou the third group hydrides and produced a consistent dissociation scheme for the entire RH family which led to the assignment of Grm~dstriim’s bands to thr m~~ltiplet transitions “I%,J S’S7 of molecular st,ates to the ground-stat.e atomic and :%I->A?+. IIis correlation terms predicted that Xrl~t, :?I,,- , and “II, would dissociat’c into ‘P, 2 (111) + ‘S, 2 (H) and “I&,~ , ‘%I2, ‘n, and “2 i would dissociate into ‘f’:i.2 (Tu ) + ‘S’, 2 CH J. * Present I’niwrsity
:iddress: I,abor:~tc)ry of (‘hiwgo. Chicago.
of Molccul:x lllin~~is.
Structltrt
:in(l Spectr:t
Physics
I kptrt rnrnil
Subsequently, the spectra of InH and InD were studied in absorption by Neuhaus (4-6’). For InH he obtained six bands in the region 44004900 8, which unreported he assigned to t.he transition ‘KI-X12+, as well as the previously (1-O) band for ?I-X’S+. The ‘II state was found to possess a very shallow potential well and exhibited a marked predissociation which led Neuhaus to place the ‘P3,s limit at approximately 22,9.50 cm-‘, based on the bottom of the x’s+ potential well. During a study of the third group dimers, the author obtained a number of unreported emission bands in the visible and red regions which appeared to be attributable to InH. Since these bands overlapped the weaker emission spectrum of In2 and generally were not calculable from the previously reported term values, it became desirable to determine their extent and subsequently their assignmenbs. Soon it became evident that the predissociations in the % state, designated in this work as a”& based on last lines calculated from Grundstriim’s data did not seem to yield results consistent with Kleman’s correlation of states and Seuhaus’ 2P31z dissociation limit. Also it was observed that in bands assigned to 3IIU+-X’S+, a marked diffuseness of the branch lines occurred prior to the last lines as calculated from Grundstrbm’s terms. In addition, in some cases’ Grundstrdm’s terms did not yield rotational lines in agreement with those measured by the author. Yursuit of these anomalies eventually led to a considerable extension of the data for InH with subsequent revisions of the molecular constants, to the analysis of several bands of the previously unobserved 311-X1Z’ transition, and to the discovery of several interesting features about the predissociation of the a% state. II. EXPERIMENTAL
Indium and hydrogen were placed in a high temperature (King) furnace and heated to temperatures up to 2OOO”C, with pressures of hydrogen varied from 200 mm to 760 mm Hg. For pressures close to one atmosphere and for temper?tures greater than 1500°C an extensive spectrum in the region 4500-8000 A could be photographed readily both in emission and absorption. Spectrograms used for rotational analysis were made in the first and second orders of a 3.4-m Jarrell-Ash plane grating Ebert spectrograph. Exposure times for the emission spectrum in second order ranged from 20 minutes to 2 hours on Kodak 103a-1; and I-K plates. The effective resolving power (greater than 100,000) and the dispersion (0.9 &mm) were sufficient to allow complete rotational analysis. Iron lines (both arc and hollow cathode) were used as standards and measurements were made using a David W. Mann Model 300 comparator. III. DESCRIPTION
AND
ANALTSIS
OF THE
SPECTRA
A. DESCRIPTION The system occurring to the long wavelength first. It has been established (3-5) that this 1 Particularly
for Q(J) lines of W-SW
side of 5000 A will be discussed system corresponds to the spin
at fairly high J values.
forl)idden transition a”&.Y’Z+. The large multiplet splitting in the nb stake produces the well separat,ed transitions ‘?I,+ --S’S .-l kl-S’S’, and “II~-S’ x _ (the multiplet components being denot,ed h.v their 12 values as s,lhscripts I. It, slrould he noted that for each R subhand system the intensity distrihutioll of the \-ibrational bands was very similar, the order of intensities being A/’ = 0 > AP = fl >> Art = fL’ (i.e., the most intense l)ands lie along t,ht> principal sec~ue~lcr I. .\lso, the R branches were generally less intense than the I’ hranchcs, which is expected hecausc of the a% upper state (7 1. In addition, in the majorit) of the hatlds in the emission spectnum, a marked diff,wnws’ occurred s1~ltlr111~ foi, the last, few ohser\-able lines. ‘I‘welvc hat& of t.lie %I,,~-S’S’ transition wre recorded and analyzed wit11 part,icular at,tcntion given to the lines of high rotational energy. Of t,hrse, oiil> the (Ok1 i, (l--Z j, (3-l ), and (8-5) hands were previously unreported. In the case of the :iII1-s’stransition, eight bands were recorded and analyzed. 0t thrse, the (2--l 1, (l-t’), and (8-3) bands were previously unreported. For t)llr hands of tllis transition, the Q branches hroke off at, ion-cr ./ tha,n ~~11tl IF predktcd f’rom the corresponding 1’ and R branches. The tratisition “&S’S+ IX forhidden by t#he selection rule AQ = 0, f 1, attd IIO hands attributed to this transition have twn reported prelkusly ~‘oJ, IIIII. In the present work two well developed, hut, weak, hands have heen ot)scrawl lyiltg COO-900 cm-’ to t,he short, wavelength side of the “II--S’2’ (Ok0 I tmd. Ilot:tt.iotlal analysis confirms t.hat, these hands have S’X+ as their 1ot~c1 statcb a11d alt upper state which corresponds t’o no stat,e previously reported, l)llt which leas rot,ational const8ants which one wo~11d expect for “II? hased otl tJhose kllowtl for %I1 and %I,*.’ r7 1 hew altd other considerations led to tht> ass&l)mctlt of these hands as the (0-O) and (l-l ) of “II--.Y’St. ;\s to ttlc ‘II-x’r+ trattsition, little of importance could he added to SWIMUS work (.$i, the only new hand ohsm~ed t)eing the (O-3 ). It might hc uotrd that ill cmissim several very diffuse lines were sometimw ohserved as cstrtlsions to t,lw prr\-ioltsly reported bands.
The wav(’ Ilumbers of the lines are given in Table The rot,atiotlal constants for all bands were obtained
1 and in Xppcndis from the rrlatioll
.\.’ (10)
304
869.28
32
(S?)(534.51)
863.10
576.9) 557.99
31 874.77
856.45
f067.03
(774.36)
849.56
(744.36 745.73
249.32
741.81
738.71
735.33
731.90
728.53
P(J)
842.37
835.21
30
616.16
082.64
27
592.46
625.19
080.85
26
234.85
828.10
605.35
632.91
(076.70)
25
2'17.30
198.40
178.4:1
158.25
R(J)
821.15
081.44
639.40
070.54
24
814.47
(076.70)
645.21
062.07
2:
808.08
802.22
P(J)
28
650.20
053.80
22
R(J)
29
654.67
P(J)
043.64
R(J)
21
992.4s
984.30
973.83
962.53
950.85
(938.88)
Q(J)
w
0
w
(6'4.80) L43.4> 625.14
4'0.%3 i (";E.35) 441.aa 447.40
WC.29
304.08
301.07
298.17
295.48
565.10
579.62
594.05
608.30
622.08
c;Y'.i*
l’,
1,
li
1:
1;
Go1.04
745.48
759.60
772.71
'784.40
134.20
153.34
774.82
LSj.56
425.X
310.65
550.51
420.10
314.50
5;,c. 09
11
167.40
180.06
812.04 uoj.y4
189.50
819:02
197.23
202.61
830.04 825.02
205.94
(834.42)
207.07
205.32
203.75
18,199.44
880.21
916.93
(950.65)
17,981.40
18,009.50
035.76
(059.92)
081.96
(102.20)
18,120.52
w
x
w
P(J)
vo.= 18,185.~~ * .15
R(J)
w
- x?z+
3-l BarId
3lI,+(o+)
/iL.%! 'Wl u3
415.06
'1'4.55
410.31
5U'i.W
jc4.04 ‘(3>.56
318.74
405.91
328.z5
(49>.7L)
'ir/.'YO
79.44
a37:9;
802.69
842.77
17,844.lO
Q(J)
(840.54)
.IO
814.11
323.22
401.91
353.64
('iSO.Oj)
P(J)
= 1'7,a44.6jt
Band
(17,8+.w)
.,o
2-l
iLl..hj
398.3:
~1.68
46G.7!!
6
- A+
1U
395.17
346.19
459.92
5
390.36
15,388.71
392.52
_90_
15,353.15
w
P(J)
4:1.55
(4?9.i'O)
418.1i
15,407.:1
_ Ii(Jl
J
i;an3
“0 = 15,3a7.10 + .06
1..
ay(l*)
c‘i !?
SPECTRUM
OF THE
2, L
:.1
4
InH MOLECULE
307
where A,F(J)" = R(J - 1) - I'(J + 1) and A$ = R(J) - P(J),hy least squares methods using an IBM 6.50 computer, as well as by standard graphical methods. Since &type doubling is present, the above method gives effective rotational constants for only one of the Q-type doublets. The effective rotational constants for the other a-type doublet were obtained from the relation Q(J)
-
~0 =
(Bp’ -
B:)J(J
+ 1) -
(D,,’ -
D:).P(J
+ 1)’ (2)
+
(H,,’ -
H:)J”(J
+ I)“,
using both least squares and graphical methods. The results are given in TabIe II, the states being labeled with both Hund’s Case a and Case c notations. It should be noted that there appears to be an anomaly in the ground state for v = 1, the B1 and D1 values not fitting smoothly with the other lower state constants. The n-type doubling constant q = B,.+ - B,.- can be obtained either from Table II or graphically from the relation A* =
The values
c/2 = [R(J) -
of q obtained
Q(J) - Q(J - 1) + I-,(-J + 1)]/2.
from Ey.
(3) for u = 0, 1, and 2 of ‘III are -0.0035
(3) f
0.0009, +O.OOOf 0.001, and +0.012 f 0.003 cm-‘, respectively; while the corresponding values from B,+ - B,-are -0.0043, -0.0017, and $0.010 cm-‘. Particular note should be made of the fact that the least squares fits of the data are extremely good, even with the relatively large values of D and H which make graphical methods somewhat hazardous. For example, the values of A$ (.I)/ (.J + !4) for the a? state fall off smoothly, but not as (.I + I$)“, for even moderate rotational energies and the inclusion of these data in the usual “best straight line” plots yields values for B which are high by more exacting curve fitting methods. Also, no sharp distortions of band structure were detected which would indicate strong perturbations, as were observed for Inn (6). Band origins were obtained by the usual graphical methods (2 1 ‘r using the equation R(J
-
1) + P(1)
= 2vo +
Z(B,'- B:).f- 2(D,'- D:)J'(.1" + I). (4)
The rotational analysis can be considered were generally observed down to their lowest observed so that generally the combination both upper and lower states for all observed bands were obtained so that careful comparison in Eq, (3) removed any doubt of assignment branch were unresolved.
unambiguous because (a) bands J values, (b) enough bands were differences could be checked for rotat’ional levels, and (c) enough of the Wype doubling as given in cases where portions of a Q
C. VIBRATIOIVAL ANALYSIS No change has been made in the previous vibrational analysis since all of the previously unobserved bands (with the exception of the ‘IT2 bands) fit into the
SPECTRIJM
OF THE
InH MOLECULE
309
TABLE III VIBRATIONAL STATE
T
e
Cr)NSTAMTS (cm-l\
u! e
3rI** (2*)
17847.2
1351. _ 2
311i (l*)
16941. Gl
1415.11
x;_ B
* .5
‘$3.5
5
* .15
ys e
-13.l![
f
.“i ,’
existing schemes. The usual series expansion of the vibrational energy (using band origins) yields the constants in Table III. The values for the ‘II? F(2’) states are only approximate since xwp and uwP would not be determined. IV. I)IscussIos
From the relative positions of the three Q components of the U”II state (see Table III), it is obvious that this state is tending strongly toward Mulliken’s Case c. This is borne out by the independence of the rotational and vibrational constants for states of different Q (for example, the Case a relationship B ?ff= B,.f 2B,'/AA is not exactly satisfied) and the fact that the nuclear hyperfine structure as studied by Neuhaus (4) does not seem to follow Case a equations. The transition is considerably more intense than the corresponding one for GaH (for which the “II state appears to be fairly close to Case a) (a), does not occur appreciably at low pressures, and seems to occur slightly less readily than the ‘II-X’2+ transition. All this seems to indicate that the AS’ selection rule is still partially effective and, therefore, the states have some slight Case a character, although the preponderance is, no doubt, Case c. For this reason each state has been labeled by bot’h its Case a and Case c designations. It was noted in the Introduction that all of the states under discussion dissociate into the ground-state atomic terms 'P (In) + ‘S (H), where the ‘1’” multiplet splitting is large: 2P3,2 - 'PII = 2212 cnl’ (12). The ‘P,,,.. + ‘&,.. terms should yield (13)Case c states I’, Of, and O- while ‘I’.?!.,.+ ‘N,!, terms should yield 2*, (3) l*, O+, and O- states which can he correlated with Case a states by Kleman’s scheme (see above) if one assumes the usual noncrossing rule. Ko evidence questioning the correctness of this correlation of states has been previously reported. Since most of the bands of the a”!&,X’Z’ tlransition are predissociated, the majority of the points of predissociation could be checked by observation of its
1. Lirnit,ing curves of dissociatic)n for InH. The empty and solid symbl,ls reprswltt und the first nhsc~wrd predissocinted terms, respectively. W11et1 thy character of it term is in doubt, the syrnl~)l is hatclwd. FIN;.
t Ire last ncmpredissociated
occurrence in several bands with a common upper stat?. The results for t,lw “II,t (I*‘) and “&+ (Ofj states are shown in Fig. 1. In this figure, the term values (based ou X’S+, 2’ = 0, J = 0) of the last nonpredissociated line and t,he first ob.serw7 predissociated line are plotted against J (,I + 1). It should hr uotcd data is that of Neuhaua (4, 6), sitlce the t’hat’ the ?I (1* )-X12+ transition furnace emission spectra showed predissociation twoadeuing for ‘II (l* I --.Y’S + at the same points as did Neuhaus’ absorption work. Examinatiou of Fig. I will rweal the following features: (a) that the “II~L (l*j and “&,+ (Ot ) states haw wry similar limiting curves of dissociation; (1)‘) that thp predissociat,ion of the l* and O+ states-because of the steep, straight-line slope- -can orcut purely by rotation in two cases only: either the potential curves have a small are essentially flat (1.5 ) fwrn maximum (II 1 or the potential curves I’ s 3.3 A ---) = ; (c) that the difference between the extrapolated efkrtive predissociation limits of the ‘n (l*) and ‘I&* (I*), “II,,+ (0’) CI~V~ is 21~iO CM-‘. whirl1 is wry near the value of the ‘I’:iC - ‘P1’? term separation for In. 111additiou, Hirge-Sponer plots of AG versus P for the ?I1 i (I*) and “II”+ (0’ 1 st,:hs dissociation limits of 20,400 cm ’ atltl yield, with very S/LO/Yextrapolations, I’aing thr dissociation limit, of the ‘II (1 ‘) states :w ‘10,700 cm--‘, respectkely.
approximately the ‘Pai? term one can estimate the atomic terms ‘P1,:! = 20,060 2 cm-’ and P312 = 22,270 cm-‘, based on X’S+ (2~ = 0). In short, all evidence points toward an apparent dissociation of the “111+(I*) and 3~0+ (O+) states into the 2P1/2+ ‘S,!? limit. It now becomes important to note (see Table I) that the “II+ (2*)-X12+ transition also shows predissociation phenomena. The sharp breakoff of the Q and R branches for the (O-O) band yields as lower limits Tz6(2-j = 21339.9 and T27(2+) = 21,589. cm-‘, respectively, where the subscript on T is J. From the (l-l) band of this transition the last sharp I> line yields Tls (2’) = 20,547.2 cm-l as a lower limit while the first very diffuse I’ line yields T18(2+) = 20,700.G cm-’ as an upper limit. Although these points were not entered in Fig. 1 it should be eq&&xed that they are in agreement with the curve drawn for the “lb+ (l+) state. Unfortunately there are not enough vibrational data to determine an apparent dissociation limit for the 3&+ (2’) states. From the preceding paragraphs it appears that all observed components for the a3B state follow essentially the same limiting curves of dissociation and that the vibrational spacing of the %11*(l*) and %10+(O+) states indicates that these states would have a vibrational convergence roughly in agreement with that predicted from the rotational predissociation. However, all of these states [particularly the “HZ&(2*) states] cannot dissociate into the ‘PljZ term as might seem to be indicated. As a result, while the data are definite, the interpretation cannot be assumed to be completely straightforward. Thus, there are several possible interpretations which shall now be discussed briefly.5 (1) Each of the potential energy curves for the “B,* (1’2 states could be assumed either to possess a very small maximum at about 3.3 A or to be completely flat from I’ = 0~ to about 1’ = 3.3 A. Such cases would be essentially indistinguishable and would be reflected (a) in an approximately correct value for the observed dissociation limit and (b) in a nonzero limiting slope of the limiting curve of dissociation as plotted in Fig. 1. Once dissociated, the 1* states could produce a heterogeneous predissociation of the O* and 2* states. It has been suggested (5’) that the breakoff of “lI- (I-) at somewhat lower energies than 3B,+ (l+) is due to a heterogeneous predissociation by the ?&- (O-) state. Such a set of potential curves as described above could be produced by avoided crossings similar to the one described for the A ‘II state of BH (15). (2) It could be assumed that a predissociation is caused by an avoided crossing with another state (at approximately 3.3 8) of the same symmetry. Such a case-probably type c+ predissociation (16)-would occur if the 3Z+(1*, O-) states attempted to dissociate into the ‘PliZ term. Such a case, however, would still require that a heterogeneous perturbation by the 1* states predissociates the 2* states. 5 It should be mentioned that if the atomic doublets were inverted, the above features would follow fairly directly. There is no evidence that this could be the case, and this passihility is mentioned only for t,he sake of completeness.
SPECTRUM
OF THE
InH MO1,~K’I~I.k~
:i 1:i
As far as the existing data is concerned explanation (1 ) HWI~S the more likely. In this explanation, however, there is still the ambiguity of where the “II,,- CO+) st’atc dissociates after the predissociation set,s in. In particular, dew ‘II,,+ (O:‘.) collGnue to the “PI,, term or is there an avoided crossing with tlw _\++ (0 ‘) st,ate-since both O+ states cannot dissociate into the “I’,‘, tjerm? Estimates using Morse potentials indicate that in no event ivould there be a cbrossing of the two O+ states at internuclear distances less than 4.5 .I, which is considerably beyond the point where the previously discussed predissociations have set, in. Lacking good theoretical guide lines, it is presrnt,ly impossihlc to state csact,ly coupling when there is an what would happen for cases of stron g spin-orbit axwided crossing and/or mixing of states of the same symmetry, although notecrossing has ,generally been considered the rule. In any event, in InH, hecause all of the components of the a% state seem to be predissociated above the et’fw tiw dissociation points of the “III+ (I+.) state, there will be little direct help from csperiment~ in the solution of this problem.
Consideration of the vibrational spacings and intensity distribution of t,lle observed bands indicates that the shapes of the pot,ential energy CUI’I’PSfor the different 12 components of the a311 stat’e are quite similar as far as the data can be observed. This fact is in conflict with the prwiously assumed dissociation scheme which postulates that the “III7 (1” ) and “II,,+ (0’ i states dissociate into different atomic multiplets, which lie about, 2200 (m” apart.6 In addition, all t#hc okwed a% multiplets shorn similar limiting curves of dissociation which est,rapolat,e to the same point for zero rotational energy. The difference between this zero rotational energy point for the u”II state and the corresponding point, for the ‘II st,atc is about 3160 cm-’ or approximately the “f’:( 2 - ‘?/)1,2term separation previously mentioned. The shape of the a”n limiting curves of cl&;I , . . . soclatlon mthcates that each of the potential curves for %I, - Cl- ) either posses;ses a vwy small maximum at about 3.3 K or is essentially flat from /’ g :I.:3 .P --_) %. ‘91 terms .\tw~*e the points of dissociation for the ‘?Il none of the remaining seems to be stable. l’ossihle esplanations for these facts are discussed :tho~~~.
R(J)
BarId
_
131.33
258.36
(827.70)
(827.70)
828.44
829.41
830.65
0;2.22
1Ti.52
l?S.!iG
201.45
22o.m
?J ..r??
Ti5.Pi
827.187
l:l'l.iB
040.87
030.63
om.10
010.51
17.000.67
lC,~'.~l.lz?
ys.87
(.17j.T3)
tic!,.
I’,
8'0.07
IO'?.08
.;'lG. 69
j'LG.88
346.1.2
3'13.79
340.30
335.77
330.43
324.34
317.61
310.26
(?5F.,Ij)
891.93
o-,0. I
285.73
276.77
957.74
977.74
17,987.28
000.87
013.64
025.85
037.59
048.90
05'1.83
070.56
ogo.95
091.30
101.44
111.47
121.42
141.22
248.82
2'67.66
151.07
302.43
(fw3.77)
P(J)
239.34
_.',8.'j
1?6.29*
BarId
160.91
(83j.94)
33
1-o l
BANDS
= 18,1go.30
18,170.73
"0
- x12+
229.68
X9.84
210.15
18,200.27
R(J)
3Iy(o*)
WAVE NOMBERS OF THE I””
294.20
515.
'VO.41
V4.06
910.37
915.30
911.90
909.18
907.11
lG.OOc1.7~
::.I
A:
X'il.RO
O'i?.i'l
(841.17)
039.0"
8j7.53
845.58
022.99
055.75
850.60
17,007."7
862.70
ii'18.13
B56.34
869i77
yc4 141
1~5,992.56
877.58
lF,88<.02
P(J)
951.19
('J38.50
0 +.7')
li,915.50
“0
o-o
= 16,904.gg * .o5
APPENDlX
Q(J)
144.69
153.06
160.13
if6.04
(170.96)
171>.07
11!3.:v+
! Si.‘lO 131 .1:
185.15
18h.5R
X7.67
188.!,1
189.15
182.55
18 ..8C
I ,O.l'I
(I:O.30)
cl?o.m)
(100.50)
(18,l'W.V~
.oe
b?(J)
630.75 622.99
057.5.2 'vx.01
985.5:
980.19
596.48
606.03
614.76
638.24
++8.ZC.
(973.60)
645.50
(652.70)
659.63
666.67
673.71
680.93
688.25
695.76
703.46
711.41
(,jit?.48i
b3.15
917.47
906.49
895.27
883.94
872.52,
861.11
849.72
838.'I!,
719.58
728.02
Bli.25 cr7.2;
736.74
1G,745.74
P(Z)
8CC.K
78k.51 . 7'l4.86
1",774.40
1-l Band Y. = 16,764.W l
(783.21)
786.03
(787.50)
(788.15)
(788.15
(787.50)
786.37
7a4:92
(783.21)
781.36
779.35
777.36
775.38
773.46
771.65
769.98
768.50
767.22
766.17
765.38
16,764.98
O(J)
.03
0 2
z
w
(843.i7)
843.56
(a43.17)
841.60
838.80
834.43
379.06
392.64
404.58
414.67
422.40
426.77
28
29
30
31
32
33
818.45
842.35
364.'70
27
35
(841.15)
348.25
26
(828.30)
839..42
34
(837.57)
313.97
(331.37)
25
835.76
(833.92)
P(J)
24
295.92
23
R(J)
277.45
J
22
110.40
116.25
111.?6
104.92
(*?)837.?2
(861.56)
097.49'
089.23
904.77 883.76
080.31~
071.04
94i.m
P(J)
923.88
'44.5'1
R(3)
061.02
051.01
Q(J)
108.82
122.96
134.78
Q(J)
'387.71
(*?)990.60
992.10
co1.71
983.46
R(J)
f497.58
('?)515.'iO
533.15
548.R
562.58
575.05
586.18
P(J)
"(55.cS
'/1;6.56
774.14
779.62
U!Jl
o-o
Band
166.17
164.99
164.15
163.54
(163.25)
517.19
534.30
551.63
568.94
(586.10)
18
19
20
21
~68. '~8
978.75
352.40 357.83
987.96
345.96
15,996.76
338.65
013.44 16,00'1.22
330.60
322.00
167.70
500.04
16
17
021.48
312.83
169.68
483.08
15
733.61
980.67
029.40
303.24
178.06
466.29
14
749.30
980.97
037.22
293.33
174.91
449,75
764.18
045.05
13
778.33
978.03 980.03
053.82
,l_Q,
-2
943.21
954.98
964.13
170.99
975.89
979.06
448.88 687.02
709.57
58ca.08
614.76
a.35
MO.14
71?.OP
719.32
718.48
716.48
(713.40)
699.29 680.39
704.89
699.50
:50.15
345.65
360.35
374.49
387.~7
400.89
413.42
425.60
437.35,
459.60 679.51
693.54
482.01 471.18
716.97
791.8:
283.16
178.24
433.46
12
974.99
672.64
492.64 664.80
503.23
804.76
971.31
648.24
523.88 513.65
656.66
630.67 639.63
534.10
544.26 621.35
554.30 612.35
17,564.19 602.93
593.41
P(J)
829.09
272.70
181.70
417.25
11
R(J) 17,583.83
817.15
840.55
EarId
966.76
955.67
1-o
Y. = 17,574.oo f .05
961.51
060.84
186.37
401.91
10
033.70 085.26
219.61 230..27
851.62
862.31
942..! 949.26
f372.62
935.00
262.25
191.21
306.84
9
102.31
209.02
076.99
111.09
198.52
240.95
120.05
882.58
188.12
153892.19
927.22
129.54
177.90
919.23
P(J)
167.83
R(J) 15,910.43
(16,138.54)
P(J)
Band
16.157.87
R(J)
2-2
Y. = 15,901.59 * .04
068.85
196.59
371.9o
6
1-l Band
3, n+(o+) - x12'
(Continued)
v. = 16,148.15 + .05
A:
251.63
209.02
202.52
216.06
330.02
5
343.54
223.67
316.98
4
357.51
2X.82
304.48
3
7
240.56
6
16,249.04
292.5o
P(J)
.oz
281.02
+
2
= 16,259.68
1
R(J)
16,z70.09
J
0
v.
APPENDIX
0 2
336.4~ .?I'.;"
(163.25)
162.85
161.91
lm.:~;
118.38
155.42
151.20
,!15.7F
(138.55)
682.56
696.55
709.52
721.27
731.5?
740.22
746.82
75n. dl
751.!1'
'101.11
116.7"
[l_l.?j)
852.39 (829.09)
348.95
(163.25)
668.03
'7'1a.1
872.82
057.50)
(163.25)
(652.70) 362.94
365.72
l769.95
801.84
891.14
907.40
922.02
Y35.30
366.38
(163.25)
147.39
365.01
636.34
958.58
362.11
(163.25)
F(J)_
(163.25)
NJ)
619.W
-p(J)
603.11
R(J)
529.97 495.52
f857.8il
'412.79
f456.86
561.00
909.80
P(J)
.886.6:,
R(J)
fGlC.'l
642.05
662.35
678.51
691.26
701.11
708.53
711.84
717.21
_ H(J)
186.0i,
212.11
-1'5.75,
.?57. Lr?
(_,TJ'.',',i
(2$.1‘?)
(Jlr.80\
P(J) --
318
SPECTRUM
318
OF THE InH MOLECULE
APPENDIX A: (Continued)
3no+(o+)- x1x+
4 1 *(l*) - x1x+ O-l “0
R(J)
2-3 Band
Band
"0 = 14,570.91 + .Ol
= 15,479.18 * .05 P(J)
Q(J)
P(J)
W
15,489.T
W
15,480.20
14,588.79
15,461.07
482.14
597.52
14,552.88 543.77
501.29 (513.72)
R(J)
3
527.10
453.45
485.04
606.14
4
541.38
446.86
488.90
614.63
534.51
5
556.55
441.1'.
(443.70)
622.89
525.18
6
572.67
4jb.43
499.45
630. go
515.74
7
589.62
432.69
506.14
638.64
506.21
8
607.42
(429.93:
513.74
646.05
496.23
9
626.06
(428.13)
522.24
653.04
486.46
10
645.44
(427.23)
531.50
659.52
476.21
11
665.59
(427.23)
541.70
665.43
465.74
12
686.46
(428.13)
552.54
670.63
454.80
13
707.99
(429.93)
564.35
675.09
443.41
14
730.06
432.55
576.98
678.57
431.46
15
752.80
436.00
589.90
680. g8
418.93
lb
776.02
440.15
603.64
682.10
405.50
17
799.68
445.12
618.00
681.76
391.06
18
823.75
450.73
632.84
679.69
375.69
19
848.17
(457.B)
648.12
675.61
358.94
20
(872.82)
(463.75)
663.82
669.14
340.69
21
879.60
471.12
679.85
659.85
320.49
22
122.42
478.91
696.04
647.09
298.30
487.05
712.43
l630.05
273.32
23 24
728.74
25
744.09
26
761.00
27
776.60
245.10
320
(:INTER ACKNVWLEIGMENTS
Support by the Advanced Research Projects Agency under Grant So. l)A-ARO(l))-31. 12-l-G316 during the period when the esperimental work and band analysis were carried out and the Kat,ional Science Foundation under Cirant ?;o. GP-28 during the preparation of this paper is gratefully acknowledged. The author wishes to thank Mrs. 1)orothy Ginter, Mr. Robert Horton, and Miss Patricia Phillips for assistance with the measurements, calculations, and figures and Professor Ii. B. Innes for many helpful discussions. RECEIVED iUarch
18, 1963 BIBLIOGRAPHY
1. 2. S. 4. 5. 6. 7. 8. 9. 10. 11. 12. 15.
14. 15. 16.
B. GRI~NDSTRO~M, 2Yature 141, 555 (1938). B. GR~YNJXSR~M,Z. Physi!~ 113, 721 (1939). B. KLEMAN, dissertation, Stockholm, 1953. H. NEIJHAI.S, Z. Physik 169, 4 (1958). H. NEC-HAI-s, 2. Physik 162, 402 (1958). H. NETHAUS, dissertation, Stockholm, 1959. A. Brn6, Z. Physik 106, 579 (1937). M. L. GINTER AND Ii. Ii. INNES, b. dfol. Spectroscopy 7, 64 (19Gl). T. LARSS~N AND H. NEVHAKS, alrkin Fysik 23, 4Gl (1963). F. H. CRAWFORDAND T. JORQENSEN,Phys. 1~~. 47, 358 (1935). G. HERZBERG, “Molecular Spectra and Molecular Struct,ure I. Spectra 2nd ed. Van Nostrand, Princeton, New Jersey 1950. Molecules,” C. E. MOORE, “Atomic Energy Levels,” Vol. III, p. 64. Xational Bureau Circular 467, Washington, D. C., 1950. R. S. MIUIKEN, Revs. Morlern Phys. 4, 26 (1932). P. H. CARRUM,, J. (‘hem. Phys. 37, 805 11962). A. C. HURLEY, Prw. Roy. Sor. A261, 237 (19Gl). R. S. MIXLIKEN, J. C’hena.Phys. 33, 247 (1960).
of Uiatomic of Standards
of the InH Molecule: of the a3n State
Characterization
*In est.ensive emission spectrum of InH, in the regicbn 1500-8000 9, has bwn obtained from a King furnace containing indium mrtal :tnd hydrogen at tenperatures greater than 1500°C. Txenby bands srising from the rr3IIo+,,+ T’S’ trxwitions h:tve been measured and nnalyzed. ()I these. thirteen had IJeen previously reported, but extensions 2nd revisions were found necessary fIl1 the interpretation of predissociation phenomens. Two previously unrep~~rte~l b:tnds hxve heen analyzed 9s the 10-O) and (1 1) bands of the trunsition u~II~T~-.Y%+. The position of the “n2d- cclmponent indiwtes t.hnt. the ~~11 st:Lte is close to Cnse c. The predissociations of the 311,=. 311, 1, and sII~,+ st:tttr II:LVC been characterized and the somewhat :rnonwlous results discuss4 it1 det.ail. I. INTKOI~L~CTIO?r
In recent years the spectrum of the InH molecule has been extensively studied. In 1938 GrundstrGm (1, 2) observed a molecular spectrL,,n in emission from a high pressure dc arc (about 7 atm of hydrogen gas) between electrodes of carhou and indium. He performed rotational analyses on twel\;r bands in the region 0 *2-\‘ and ‘II-3 of IuH, and X30-72.50 A, which he assigned to two transitions noted that t,he intensity of the spectrum was pressure dependent, the bands 20 mm Hg and showing appreciable being unobservable at approximately intensity only for pressures of approximately out’ atmosphere or greater. III addition, he pointed out that the ‘n-2 hauds broke off sharply, indicating a predissociation, and that the Q branch broke off at lower energy than the f’ aud R branches. Unfortunately, he did not report. his original data, hut list.4 only the calculated rot,ational term vahw~, a fact which has caused a great deal of additional labor in the present work. Kleman (J) examined the existing data ou the third group hydrides and produced a consistent dissociation scheme for the entire RH family which led to the assignment of Grm~dstriim’s bands to thr m~~ltiplet transitions “I%,J S’S7 of molecular st,ates to the ground-stat.e atomic and :%I->A?+. IIis correlation terms predicted that Xrl~t, :?I,,- , and “II, would dissociat’c into ‘P, 2 (111) + ‘S, 2 (H) and “I&,~ , ‘%I2, ‘n, and “2 i would dissociate into ‘f’:i.2 (Tu ) + ‘S’, 2 CH J. * Present I’niwrsity
:iddress: I,abor:~tc)ry of (‘hiwgo. Chicago.
of Molccul:x lllin~~is.
Structltrt
:in(l Spectr:t
Physics
I kptrt rnrnil
Subsequently, the spectra of InH and InD were studied in absorption by Neuhaus (4-6’). For InH he obtained six bands in the region 44004900 8, which unreported he assigned to t.he transition ‘KI-X12+, as well as the previously (1-O) band for ?I-X’S+. The ‘II state was found to possess a very shallow potential well and exhibited a marked predissociation which led Neuhaus to place the ‘P3,s limit at approximately 22,9.50 cm-‘, based on the bottom of the x’s+ potential well. During a study of the third group dimers, the author obtained a number of unreported emission bands in the visible and red regions which appeared to be attributable to InH. Since these bands overlapped the weaker emission spectrum of In2 and generally were not calculable from the previously reported term values, it became desirable to determine their extent and subsequently their assignmenbs. Soon it became evident that the predissociations in the % state, designated in this work as a”& based on last lines calculated from Grundstriim’s data did not seem to yield results consistent with Kleman’s correlation of states and Seuhaus’ 2P31z dissociation limit. Also it was observed that in bands assigned to 3IIU+-X’S+, a marked diffuseness of the branch lines occurred prior to the last lines as calculated from Grundstrbm’s terms. In addition, in some cases’ Grundstrdm’s terms did not yield rotational lines in agreement with those measured by the author. Yursuit of these anomalies eventually led to a considerable extension of the data for InH with subsequent revisions of the molecular constants, to the analysis of several bands of the previously unobserved 311-X1Z’ transition, and to the discovery of several interesting features about the predissociation of the a% state. II. EXPERIMENTAL
Indium and hydrogen were placed in a high temperature (King) furnace and heated to temperatures up to 2OOO”C, with pressures of hydrogen varied from 200 mm to 760 mm Hg. For pressures close to one atmosphere and for temper?tures greater than 1500°C an extensive spectrum in the region 4500-8000 A could be photographed readily both in emission and absorption. Spectrograms used for rotational analysis were made in the first and second orders of a 3.4-m Jarrell-Ash plane grating Ebert spectrograph. Exposure times for the emission spectrum in second order ranged from 20 minutes to 2 hours on Kodak 103a-1; and I-K plates. The effective resolving power (greater than 100,000) and the dispersion (0.9 &mm) were sufficient to allow complete rotational analysis. Iron lines (both arc and hollow cathode) were used as standards and measurements were made using a David W. Mann Model 300 comparator. III. DESCRIPTION
AND
ANALTSIS
OF THE
SPECTRA
A. DESCRIPTION The system occurring to the long wavelength first. It has been established (3-5) that this 1 Particularly
for Q(J) lines of W-SW
side of 5000 A will be discussed system corresponds to the spin
at fairly high J values.
forl)idden transition a”&.Y’Z+. The large multiplet splitting in the nb stake produces the well separat,ed transitions ‘?I,+ --S’S .-l kl-S’S’, and “II~-S’ x _ (the multiplet components being denot,ed h.v their 12 values as s,lhscripts I. It, slrould he noted that for each R subhand system the intensity distrihutioll of the \-ibrational bands was very similar, the order of intensities being A/’ = 0 > AP = fl >> Art = fL’ (i.e., the most intense l)ands lie along t,ht> principal sec~ue~lcr I. .\lso, the R branches were generally less intense than the I’ hranchcs, which is expected hecausc of the a% upper state (7 1. In addition, in the majorit) of the hatlds in the emission spectnum, a marked diff,wnws’ occurred s1~ltlr111~ foi, the last, few ohser\-able lines. ‘I‘welvc hat& of t.lie %I,,~-S’S’ transition wre recorded and analyzed wit11 part,icular at,tcntion given to the lines of high rotational energy. Of t,hrse, oiil> the (Ok1 i, (l--Z j, (3-l ), and (8-5) hands were previously unreported. In the case of the :iII1-s’stransition, eight bands were recorded and analyzed. 0t thrse, the (2--l 1, (l-t’), and (8-3) bands were previously unreported. For t)llr hands of tllis transition, the Q branches hroke off at, ion-cr ./ tha,n ~~11tl IF predktcd f’rom the corresponding 1’ and R branches. The tratisition “&S’S+ IX forhidden by t#he selection rule AQ = 0, f 1, attd IIO hands attributed to this transition have twn reported prelkusly ~‘oJ, IIIII. In the present work two well developed, hut, weak, hands have heen ot)scrawl lyiltg COO-900 cm-’ to t,he short, wavelength side of the “II--S’2’ (Ok0 I tmd. Ilot:tt.iotlal analysis confirms t.hat, these hands have S’X+ as their 1ot~c1 statcb a11d alt upper state which corresponds t’o no stat,e previously reported, l)llt which leas rot,ational const8ants which one wo~11d expect for “II? hased otl tJhose kllowtl for %I1 and %I,*.’ r7 1 hew altd other considerations led to tht> ass&l)mctlt of these hands as the (0-O) and (l-l ) of “II--.Y’St. ;\s to ttlc ‘II-x’r+ trattsition, little of importance could he added to SWIMUS work (.$i, the only new hand ohsm~ed t)eing the (O-3 ). It might hc uotrd that ill cmissim several very diffuse lines were sometimw ohserved as cstrtlsions to t,lw prr\-ioltsly reported bands.
The wav(’ Ilumbers of the lines are given in Table The rot,atiotlal constants for all bands were obtained
1 and in Xppcndis from the rrlatioll
.\.’ (10)
304
869.28
32
(S?)(534.51)
863.10
576.9) 557.99
31 874.77
856.45
f067.03
(774.36)
849.56
(744.36 745.73
249.32
741.81
738.71
735.33
731.90
728.53
P(J)
842.37
835.21
30
616.16
082.64
27
592.46
625.19
080.85
26
234.85
828.10
605.35
632.91
(076.70)
25
2'17.30
198.40
178.4:1
158.25
R(J)
821.15
081.44
639.40
070.54
24
814.47
(076.70)
645.21
062.07
2:
808.08
802.22
P(J)
28
650.20
053.80
22
R(J)
29
654.67
P(J)
043.64
R(J)
21
992.4s
984.30
973.83
962.53
950.85
(938.88)
Q(J)
w
0
w
(6'4.80) L43.4> 625.14
4'0.%3 i (";E.35) 441.aa 447.40
WC.29
304.08
301.07
298.17
295.48
565.10
579.62
594.05
608.30
622.08
c;Y'.i*
l’,
1,
li
1:
1;
Go1.04
745.48
759.60
772.71
'784.40
134.20
153.34
774.82
LSj.56
425.X
310.65
550.51
420.10
314.50
5;,c. 09
11
167.40
180.06
812.04 uoj.y4
189.50
819:02
197.23
202.61
830.04 825.02
205.94
(834.42)
207.07
205.32
203.75
18,199.44
880.21
916.93
(950.65)
17,981.40
18,009.50
035.76
(059.92)
081.96
(102.20)
18,120.52
w
x
w
P(J)
vo.= 18,185.~~ * .15
R(J)
w
- x?z+
3-l BarId
3lI,+(o+)
/iL.%! 'Wl u3
415.06
'1'4.55
410.31
5U'i.W
jc4.04 ‘(3>.56
318.74
405.91
328.z5
(49>.7L)
'ir/.'YO
79.44
a37:9;
802.69
842.77
17,844.lO
Q(J)
(840.54)
.IO
814.11
323.22
401.91
353.64
('iSO.Oj)
P(J)
= 1'7,a44.6jt
Band
(17,8+.w)
.,o
2-l
iLl..hj
398.3:
~1.68
46G.7!!
6
- A+
1U
395.17
346.19
459.92
5
390.36
15,388.71
392.52
_90_
15,353.15
w
P(J)
4:1.55
(4?9.i'O)
418.1i
15,407.:1
_ Ii(Jl
J
i;an3
“0 = 15,3a7.10 + .06
1..
ay(l*)
c‘i !?
SPECTRUM
OF THE
2, L
:.1
4
InH MOLECULE
307
where A,F(J)" = R(J - 1) - I'(J + 1) and A$ = R(J) - P(J),hy least squares methods using an IBM 6.50 computer, as well as by standard graphical methods. Since &type doubling is present, the above method gives effective rotational constants for only one of the Q-type doublets. The effective rotational constants for the other a-type doublet were obtained from the relation Q(J)
-
~0 =
(Bp’ -
B:)J(J
+ 1) -
(D,,’ -
D:).P(J
+ 1)’ (2)
+
(H,,’ -
H:)J”(J
+ I)“,
using both least squares and graphical methods. The results are given in TabIe II, the states being labeled with both Hund’s Case a and Case c notations. It should be noted that there appears to be an anomaly in the ground state for v = 1, the B1 and D1 values not fitting smoothly with the other lower state constants. The n-type doubling constant q = B,.+ - B,.- can be obtained either from Table II or graphically from the relation A* =
The values
c/2 = [R(J) -
of q obtained
Q(J) - Q(J - 1) + I-,(-J + 1)]/2.
from Ey.
(3) for u = 0, 1, and 2 of ‘III are -0.0035
(3) f
0.0009, +O.OOOf 0.001, and +0.012 f 0.003 cm-‘, respectively; while the corresponding values from B,+ - B,-are -0.0043, -0.0017, and $0.010 cm-‘. Particular note should be made of the fact that the least squares fits of the data are extremely good, even with the relatively large values of D and H which make graphical methods somewhat hazardous. For example, the values of A$ (.I)/ (.J + !4) for the a? state fall off smoothly, but not as (.I + I$)“, for even moderate rotational energies and the inclusion of these data in the usual “best straight line” plots yields values for B which are high by more exacting curve fitting methods. Also, no sharp distortions of band structure were detected which would indicate strong perturbations, as were observed for Inn (6). Band origins were obtained by the usual graphical methods (2 1 ‘r using the equation R(J
-
1) + P(1)
= 2vo +
Z(B,'- B:).f- 2(D,'- D:)J'(.1" + I). (4)
The rotational analysis can be considered were generally observed down to their lowest observed so that generally the combination both upper and lower states for all observed bands were obtained so that careful comparison in Eq, (3) removed any doubt of assignment branch were unresolved.
unambiguous because (a) bands J values, (b) enough bands were differences could be checked for rotat’ional levels, and (c) enough of the Wype doubling as given in cases where portions of a Q
C. VIBRATIOIVAL ANALYSIS No change has been made in the previous vibrational analysis since all of the previously unobserved bands (with the exception of the ‘IT2 bands) fit into the
SPECTRIJM
OF THE
InH MOLECULE
309
TABLE III VIBRATIONAL STATE
T
e
Cr)NSTAMTS (cm-l\
u! e
3rI** (2*)
17847.2
1351. _ 2
311i (l*)
16941. Gl
1415.11
x;_ B
* .5
‘$3.5
5
* .15
ys e
-13.l![
f
.“i ,’
existing schemes. The usual series expansion of the vibrational energy (using band origins) yields the constants in Table III. The values for the ‘II? F(2’) states are only approximate since xwp and uwP would not be determined. IV. I)IscussIos
From the relative positions of the three Q components of the U”II state (see Table III), it is obvious that this state is tending strongly toward Mulliken’s Case c. This is borne out by the independence of the rotational and vibrational constants for states of different Q (for example, the Case a relationship B ?ff= B,.f 2B,'/AA is not exactly satisfied) and the fact that the nuclear hyperfine structure as studied by Neuhaus (4) does not seem to follow Case a equations. The transition is considerably more intense than the corresponding one for GaH (for which the “II state appears to be fairly close to Case a) (a), does not occur appreciably at low pressures, and seems to occur slightly less readily than the ‘II-X’2+ transition. All this seems to indicate that the AS’ selection rule is still partially effective and, therefore, the states have some slight Case a character, although the preponderance is, no doubt, Case c. For this reason each state has been labeled by bot’h its Case a and Case c designations. It was noted in the Introduction that all of the states under discussion dissociate into the ground-state atomic terms 'P (In) + ‘S (H), where the ‘1’” multiplet splitting is large: 2P3,2 - 'PII = 2212 cnl’ (12). The ‘P,,,.. + ‘&,.. terms should yield (13)Case c states I’, Of, and O- while ‘I’.?!.,.+ ‘N,!, terms should yield 2*, (3) l*, O+, and O- states which can he correlated with Case a states by Kleman’s scheme (see above) if one assumes the usual noncrossing rule. Ko evidence questioning the correctness of this correlation of states has been previously reported. Since most of the bands of the a”!&,X’Z’ tlransition are predissociated, the majority of the points of predissociation could be checked by observation of its
1. Lirnit,ing curves of dissociatic)n for InH. The empty and solid symbl,ls reprswltt und the first nhsc~wrd predissocinted terms, respectively. W11et1 thy character of it term is in doubt, the syrnl~)l is hatclwd. FIN;.
t Ire last ncmpredissociated
occurrence in several bands with a common upper stat?. The results for t,lw “II,t (I*‘) and “&+ (Ofj states are shown in Fig. 1. In this figure, the term values (based ou X’S+, 2’ = 0, J = 0) of the last nonpredissociated line and t,he first ob.serw7 predissociated line are plotted against J (,I + 1). It should hr uotcd data is that of Neuhaua (4, 6), sitlce the t’hat’ the ?I (1* )-X12+ transition furnace emission spectra showed predissociation twoadeuing for ‘II (l* I --.Y’S + at the same points as did Neuhaus’ absorption work. Examinatiou of Fig. I will rweal the following features: (a) that the “II~L (l*j and “&,+ (Ot ) states haw wry similar limiting curves of dissociation; (1)‘) that thp predissociat,ion of the l* and O+ states-because of the steep, straight-line slope- -can orcut purely by rotation in two cases only: either the potential curves have a small are essentially flat (1.5 ) fwrn maximum (II 1 or the potential curves I’ s 3.3 A ---) = ; (c) that the difference between the extrapolated efkrtive predissociation limits of the ‘n (l*) and ‘I&* (I*), “II,,+ (0’) CI~V~ is 21~iO CM-‘. whirl1 is wry near the value of the ‘I’:iC - ‘P1’? term separation for In. 111additiou, Hirge-Sponer plots of AG versus P for the ?I1 i (I*) and “II”+ (0’ 1 st,:hs dissociation limits of 20,400 cm ’ atltl yield, with very S/LO/Yextrapolations, I’aing thr dissociation limit, of the ‘II (1 ‘) states :w ‘10,700 cm--‘, respectkely.
approximately the ‘Pai? term one can estimate the atomic terms ‘P1,:! = 20,060 2 cm-’ and P312 = 22,270 cm-‘, based on X’S+ (2~ = 0). In short, all evidence points toward an apparent dissociation of the “111+(I*) and 3~0+ (O+) states into the 2P1/2+ ‘S,!? limit. It now becomes important to note (see Table I) that the “II+ (2*)-X12+ transition also shows predissociation phenomena. The sharp breakoff of the Q and R branches for the (O-O) band yields as lower limits Tz6(2-j = 21339.9 and T27(2+) = 21,589. cm-‘, respectively, where the subscript on T is J. From the (l-l) band of this transition the last sharp I> line yields Tls (2’) = 20,547.2 cm-l as a lower limit while the first very diffuse I’ line yields T18(2+) = 20,700.G cm-’ as an upper limit. Although these points were not entered in Fig. 1 it should be eq&&xed that they are in agreement with the curve drawn for the “lb+ (l+) state. Unfortunately there are not enough vibrational data to determine an apparent dissociation limit for the 3&+ (2’) states. From the preceding paragraphs it appears that all observed components for the a3B state follow essentially the same limiting curves of dissociation and that the vibrational spacing of the %11*(l*) and %10+(O+) states indicates that these states would have a vibrational convergence roughly in agreement with that predicted from the rotational predissociation. However, all of these states [particularly the “HZ&(2*) states] cannot dissociate into the ‘PljZ term as might seem to be indicated. As a result, while the data are definite, the interpretation cannot be assumed to be completely straightforward. Thus, there are several possible interpretations which shall now be discussed briefly.5 (1) Each of the potential energy curves for the “B,* (1’2 states could be assumed either to possess a very small maximum at about 3.3 A or to be completely flat from I’ = 0~ to about 1’ = 3.3 A. Such cases would be essentially indistinguishable and would be reflected (a) in an approximately correct value for the observed dissociation limit and (b) in a nonzero limiting slope of the limiting curve of dissociation as plotted in Fig. 1. Once dissociated, the 1* states could produce a heterogeneous predissociation of the O* and 2* states. It has been suggested (5’) that the breakoff of “lI- (I-) at somewhat lower energies than 3B,+ (l+) is due to a heterogeneous predissociation by the ?&- (O-) state. Such a set of potential curves as described above could be produced by avoided crossings similar to the one described for the A ‘II state of BH (15). (2) It could be assumed that a predissociation is caused by an avoided crossing with another state (at approximately 3.3 8) of the same symmetry. Such a case-probably type c+ predissociation (16)-would occur if the 3Z+(1*, O-) states attempted to dissociate into the ‘PliZ term. Such a case, however, would still require that a heterogeneous perturbation by the 1* states predissociates the 2* states. 5 It should be mentioned that if the atomic doublets were inverted, the above features would follow fairly directly. There is no evidence that this could be the case, and this passihility is mentioned only for t,he sake of completeness.
SPECTRUM
OF THE
InH MO1,~K’I~I.k~
:i 1:i
As far as the existing data is concerned explanation (1 ) HWI~S the more likely. In this explanation, however, there is still the ambiguity of where the “II,,- CO+) st’atc dissociates after the predissociation set,s in. In particular, dew ‘II,,+ (O:‘.) collGnue to the “PI,, term or is there an avoided crossing with tlw _\++ (0 ‘) st,ate-since both O+ states cannot dissociate into the “I’,‘, tjerm? Estimates using Morse potentials indicate that in no event ivould there be a cbrossing of the two O+ states at internuclear distances less than 4.5 .I, which is considerably beyond the point where the previously discussed predissociations have set, in. Lacking good theoretical guide lines, it is presrnt,ly impossihlc to state csact,ly coupling when there is an what would happen for cases of stron g spin-orbit axwided crossing and/or mixing of states of the same symmetry, although notecrossing has ,generally been considered the rule. In any event, in InH, hecause all of the components of the a% state seem to be predissociated above the et’fw tiw dissociation points of the “III+ (I+.) state, there will be little direct help from csperiment~ in the solution of this problem.
Consideration of the vibrational spacings and intensity distribution of t,lle observed bands indicates that the shapes of the pot,ential energy CUI’I’PSfor the different 12 components of the a311 stat’e are quite similar as far as the data can be observed. This fact is in conflict with the prwiously assumed dissociation scheme which postulates that the “III7 (1” ) and “II,,+ (0’ i states dissociate into different atomic multiplets, which lie about, 2200 (m” apart.6 In addition, all t#hc okwed a% multiplets shorn similar limiting curves of dissociation which est,rapolat,e to the same point for zero rotational energy. The difference between this zero rotational energy point for the u”II state and the corresponding point, for the ‘II st,atc is about 3160 cm-’ or approximately the “f’:( 2 - ‘?/)1,2term separation previously mentioned. The shape of the a”n limiting curves of cl&;I , . . . soclatlon mthcates that each of the potential curves for %I, - Cl- ) either posses;ses a vwy small maximum at about 3.3 K or is essentially flat from /’ g :I.:3 .P --_) %. ‘91 terms .\tw~*e the points of dissociation for the ‘?Il none of the remaining seems to be stable. l’ossihle esplanations for these facts are discussed :tho~~~.
R(J)
BarId
_
131.33
258.36
(827.70)
(827.70)
828.44
829.41
830.65
0;2.22
1Ti.52
l?S.!iG
201.45
22o.m
?J ..r??
Ti5.Pi
827.187
l:l'l.iB
040.87
030.63
om.10
010.51
17.000.67
lC,~'.~l.lz?
ys.87
(.17j.T3)
tic!,.
I’,
8'0.07
IO'?.08
.;'lG. 69
j'LG.88
346.1.2
3'13.79
340.30
335.77
330.43
324.34
317.61
310.26
(?5F.,Ij)
891.93
o-,0. I
285.73
276.77
957.74
977.74
17,987.28
000.87
013.64
025.85
037.59
048.90
05'1.83
070.56
ogo.95
091.30
101.44
111.47
121.42
141.22
248.82
2'67.66
151.07
302.43
(fw3.77)
P(J)
239.34
_.',8.'j
1?6.29*
BarId
160.91
(83j.94)
33
1-o l
BANDS
= 18,1go.30
18,170.73
"0
- x12+
229.68
X9.84
210.15
18,200.27
R(J)
3Iy(o*)
WAVE NOMBERS OF THE I””
294.20
515.
'VO.41
V4.06
910.37
915.30
911.90
909.18
907.11
lG.OOc1.7~
::.I
A:
X'il.RO
O'i?.i'l
(841.17)
039.0"
8j7.53
845.58
022.99
055.75
850.60
17,007."7
862.70
ii'18.13
B56.34
869i77
yc4 141
1~5,992.56
877.58
lF,88<.02
P(J)
951.19
('J38.50
0 +.7')
li,915.50
“0
o-o
= 16,904.gg * .o5
APPENDlX
Q(J)
144.69
153.06
160.13
if6.04
(170.96)
171>.07
11!3.:v+
! Si.‘lO 131 .1:
185.15
18h.5R
X7.67
188.!,1
189.15
182.55
18 ..8C
I ,O.l'I
(I:O.30)
cl?o.m)
(100.50)
(18,l'W.V~
.oe
b?(J)
630.75 622.99
057.5.2 'vx.01
985.5:
980.19
596.48
606.03
614.76
638.24
++8.ZC.
(973.60)
645.50
(652.70)
659.63
666.67
673.71
680.93
688.25
695.76
703.46
711.41
(,jit?.48i
b3.15
917.47
906.49
895.27
883.94
872.52,
861.11
849.72
838.'I!,
719.58
728.02
Bli.25 cr7.2;
736.74
1G,745.74
P(Z)
8CC.K
78k.51 . 7'l4.86
1",774.40
1-l Band Y. = 16,764.W l
(783.21)
786.03
(787.50)
(788.15)
(788.15
(787.50)
786.37
7a4:92
(783.21)
781.36
779.35
777.36
775.38
773.46
771.65
769.98
768.50
767.22
766.17
765.38
16,764.98
O(J)
.03
0 2
z
w
(843.i7)
843.56
(a43.17)
841.60
838.80
834.43
379.06
392.64
404.58
414.67
422.40
426.77
28
29
30
31
32
33
818.45
842.35
364.'70
27
35
(841.15)
348.25
26
(828.30)
839..42
34
(837.57)
313.97
(331.37)
25
835.76
(833.92)
P(J)
24
295.92
23
R(J)
277.45
J
22
110.40
116.25
111.?6
104.92
(*?)837.?2
(861.56)
097.49'
089.23
904.77 883.76
080.31~
071.04
94i.m
P(J)
923.88
'44.5'1
R(3)
061.02
051.01
Q(J)
108.82
122.96
134.78
Q(J)
'387.71
(*?)990.60
992.10
co1.71
983.46
R(J)
f497.58
('?)515.'iO
533.15
548.R
562.58
575.05
586.18
P(J)
"(55.cS
'/1;6.56
774.14
779.62
U!Jl
o-o
Band
166.17
164.99
164.15
163.54
(163.25)
517.19
534.30
551.63
568.94
(586.10)
18
19
20
21
~68. '~8
978.75
352.40 357.83
987.96
345.96
15,996.76
338.65
013.44 16,00'1.22
330.60
322.00
167.70
500.04
16
17
021.48
312.83
169.68
483.08
15
733.61
980.67
029.40
303.24
178.06
466.29
14
749.30
980.97
037.22
293.33
174.91
449,75
764.18
045.05
13
778.33
978.03 980.03
053.82
,l_Q,
-2
943.21
954.98
964.13
170.99
975.89
979.06
448.88 687.02
709.57
58ca.08
614.76
a.35
MO.14
71?.OP
719.32
718.48
716.48
(713.40)
699.29 680.39
704.89
699.50
:50.15
345.65
360.35
374.49
387.~7
400.89
413.42
425.60
437.35,
459.60 679.51
693.54
482.01 471.18
716.97
791.8:
283.16
178.24
433.46
12
974.99
672.64
492.64 664.80
503.23
804.76
971.31
648.24
523.88 513.65
656.66
630.67 639.63
534.10
544.26 621.35
554.30 612.35
17,564.19 602.93
593.41
P(J)
829.09
272.70
181.70
417.25
11
R(J) 17,583.83
817.15
840.55
EarId
966.76
955.67
1-o
Y. = 17,574.oo f .05
961.51
060.84
186.37
401.91
10
033.70 085.26
219.61 230..27
851.62
862.31
942..! 949.26
f372.62
935.00
262.25
191.21
306.84
9
102.31
209.02
076.99
111.09
198.52
240.95
120.05
882.58
188.12
153892.19
927.22
129.54
177.90
919.23
P(J)
167.83
R(J) 15,910.43
(16,138.54)
P(J)
Band
16.157.87
R(J)
2-2
Y. = 15,901.59 * .04
068.85
196.59
371.9o
6
1-l Band
3, n+(o+) - x12'
(Continued)
v. = 16,148.15 + .05
A:
251.63
209.02
202.52
216.06
330.02
5
343.54
223.67
316.98
4
357.51
2X.82
304.48
3
7
240.56
6
16,249.04
292.5o
P(J)
.oz
281.02
+
2
= 16,259.68
1
R(J)
16,z70.09
J
0
v.
APPENDIX
0 2
336.4~ .?I'.;"
(163.25)
162.85
161.91
lm.:~;
118.38
155.42
151.20
,!15.7F
(138.55)
682.56
696.55
709.52
721.27
731.5?
740.22
746.82
75n. dl
751.!1'
'101.11
116.7"
[l_l.?j)
852.39 (829.09)
348.95
(163.25)
668.03
'7'1a.1
872.82
057.50)
(163.25)
(652.70) 362.94
365.72
l769.95
801.84
891.14
907.40
922.02
Y35.30
366.38
(163.25)
147.39
365.01
636.34
958.58
362.11
(163.25)
F(J)_
(163.25)
NJ)
619.W
-p(J)
603.11
R(J)
529.97 495.52
f857.8il
'412.79
f456.86
561.00
909.80
P(J)
.886.6:,
R(J)
fGlC.'l
642.05
662.35
678.51
691.26
701.11
708.53
711.84
717.21
_ H(J)
186.0i,
212.11
-1'5.75,
.?57. Lr?
(_,TJ'.',',i
(2$.1‘?)
(Jlr.80\
P(J) --
318
SPECTRUM
318
OF THE InH MOLECULE
APPENDIX A: (Continued)
3no+(o+)- x1x+
4 1 *(l*) - x1x+ O-l “0
R(J)
2-3 Band
Band
"0 = 14,570.91 + .Ol
= 15,479.18 * .05 P(J)
Q(J)
P(J)
W
15,489.T
W
15,480.20
14,588.79
15,461.07
482.14
597.52
14,552.88 543.77
501.29 (513.72)
R(J)
3
527.10
453.45
485.04
606.14
4
541.38
446.86
488.90
614.63
534.51
5
556.55
441.1'.
(443.70)
622.89
525.18
6
572.67
4jb.43
499.45
630. go
515.74
7
589.62
432.69
506.14
638.64
506.21
8
607.42
(429.93:
513.74
646.05
496.23
9
626.06
(428.13)
522.24
653.04
486.46
10
645.44
(427.23)
531.50
659.52
476.21
11
665.59
(427.23)
541.70
665.43
465.74
12
686.46
(428.13)
552.54
670.63
454.80
13
707.99
(429.93)
564.35
675.09
443.41
14
730.06
432.55
576.98
678.57
431.46
15
752.80
436.00
589.90
680. g8
418.93
lb
776.02
440.15
603.64
682.10
405.50
17
799.68
445.12
618.00
681.76
391.06
18
823.75
450.73
632.84
679.69
375.69
19
848.17
(457.B)
648.12
675.61
358.94
20
(872.82)
(463.75)
663.82
669.14
340.69
21
879.60
471.12
679.85
659.85
320.49
22
122.42
478.91
696.04
647.09
298.30
487.05
712.43
l630.05
273.32
23 24
728.74
25
744.09
26
761.00
27
776.60
245.10
320
(:INTER ACKNVWLEIGMENTS
Support by the Advanced Research Projects Agency under Grant So. l)A-ARO(l))-31. 12-l-G316 during the period when the esperimental work and band analysis were carried out and the Kat,ional Science Foundation under Cirant ?;o. GP-28 during the preparation of this paper is gratefully acknowledged. The author wishes to thank Mrs. 1)orothy Ginter, Mr. Robert Horton, and Miss Patricia Phillips for assistance with the measurements, calculations, and figures and Professor Ii. B. Innes for many helpful discussions. RECEIVED iUarch
18, 1963 BIBLIOGRAPHY
1. 2. S. 4. 5. 6. 7. 8. 9. 10. 11. 12. 15.
14. 15. 16.
B. GRI~NDSTRO~M, 2Yature 141, 555 (1938). B. GR~YNJXSR~M,Z. Physi!~ 113, 721 (1939). B. KLEMAN, dissertation, Stockholm, 1953. H. NEIJHAI.S, Z. Physik 169, 4 (1958). H. NEC-HAI-s, 2. Physik 162, 402 (1958). H. NETHAUS, dissertation, Stockholm, 1959. A. Brn6, Z. Physik 106, 579 (1937). M. L. GINTER AND Ii. Ii. INNES, b. dfol. Spectroscopy 7, 64 (19Gl). T. LARSS~N AND H. NEVHAKS, alrkin Fysik 23, 4Gl (1963). F. H. CRAWFORDAND T. JORQENSEN,Phys. 1~~. 47, 358 (1935). G. HERZBERG, “Molecular Spectra and Molecular Struct,ure I. Spectra 2nd ed. Van Nostrand, Princeton, New Jersey 1950. Molecules,” C. E. MOORE, “Atomic Energy Levels,” Vol. III, p. 64. Xational Bureau Circular 467, Washington, D. C., 1950. R. S. MIUIKEN, Revs. Morlern Phys. 4, 26 (1932). P. H. CARRUM,, J. (‘hem. Phys. 37, 805 11962). A. C. HURLEY, Prw. Roy. Sor. A261, 237 (19Gl). R. S. MIXLIKEN, J. C’hena.Phys. 33, 247 (1960).
of Uiatomic of Standards