Rotational analysis of the A0+-X0+ and B1-X0+ systems of indium bromide

JOURNAL OF MOLECULAR SPECTROSCOPY

119,405-417 (1986)

Rotational Analysis of the AO+-X0+ and Bl -X0+ Systems of lndium Bromide SARMA N. VEMPATI AND WILLIAM E. JONES Department of Chemistry, Dalhousie University, Halifax. Nova Scotia, Canada B3H 4J3

The rotationalanalysis of the O-Obands of the AO+-X0+and Bl-X0+ systems of indium bromide is reported. The rotational constants have been determined as B,=,, = 0.058314 and B._,, = 0.058149 cm-’ for the AOCand Bl states of In79Br and BUzo= 0.057454 and BVzO= 0.057297 cm -’ for the AO+and Bl states of In*‘Br. 0 1986 Academic PBS. IIIC. INTRODUCTION

Although spectra of the monohalides of the group BIB atoms have been known since the early 1930s (1, 2), little has been reported on the rotational analysis of InBr or InI. These molecules are found to have strong emission and absorption band systems in the ultraviolet and visible regions of the electromagnetic spectrum. The spectra result from the transitions AO+-X0+, Bl-X0+, and C l-X0+. In the case of InBr, the strong A-X and B-X systems, found in both absorption and emission fall in the region 3590-3980 A while the weaker system C 1-.X0+, found only in absorption, falls in the region 2850-3050 A. The vibrational analyses of the A-X and B-X systems were revised and extended recently (3). A more recent note (4) reports the rotational constants of InBr from spectra recorded at 0.5 A/m. At this dispersion, large portions of the bands remain unresolved making the analysis difficult and somewhat tentative. A study of the microwave spectrum of InBr (5) has provided very accurate values of the rotational constants of the ground state. In order to obtain accurate rotational constants and to confirm the electronic states involved, we recorded the spectra of InBr under the highest possible dispersion. The results of the analysis of the O-O bands of the B-X and A-X systems for both isotopic species are presented here. EXPERIMENTAL

DETAILS

The emission spectra recorded here were produced in a microwave discharge (2450 MHz) by continuously passing bromine vapor over slightly heated indium metal. The spectra were recorded with exposures of 5 to 60 min on Kodak 103-O plates using the 8.8-m Ebert vacuum spectrograph at the National Research Council, Ottawa, Canada. The reciprocal dispersion is approximately 0.13 A/mm in the 14th and 15th orders. Iron lines from a hollow cathode discharge lamp provided the reference lines. The plates were measured on a photoelectric comparator and the measurements are reduced to wavenumbers accurate to within t-O.02 cm-’ for single resolved lines. 405

0022-2852186 $3.00 Copyright 0 1986 by Academic Press, Inc. All rights of reproduction in any form reserved

VEMPATI AND JONES

f;‘ro. 1.The O-O bands of the .40+-X0+ system of InBr. Those lines designated as Rl and Pi are for In”Br while the R2 lines ale for in79Br. P lines for In?& are mergedwiththe R branchof fn”Br.

RESULTS Natural indium has two isotopes “‘In (95.72%) and li31n (4.28%). Bromine also occurs in two isotopic forms 79Br (50.54%) and “Br (49.46%) (6). The spectra of “51n79Br and i’51n8LBrwould be expected to be equally strong, while spectra of the ‘131n isotope should not be strong enough to interfere and are not observed. Apart

FIG. 2. The O-O bands of the H-X0+ system of InBr. Those lines designated as Rl, Pl, and (21 are for In”Br, while those designated as R2, P2, and Q2 are for In79Br. 407

408

VEMPATI AND JONES TABLE I Wavenumbers of the Lines Identified in the O-O Band of the ,40+-X0+ Transition (cm-‘) INBR 79 P

J 0 :

3

26600.12 00.01 599.91

4 : 87 9 10 11 12 13 14 15 16 :e' 19 20 ii

23 24 25 26 27 20 29 30 3'2 33 :t :76 :89 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 ;z xs7 209 512 63 St

00.12 00.23 00.35 00.47 00.59

00.72 00.85 01.00 01.15 01.30 01.45 01.61 01;79 01.95 02.13 02.32 02.51 02.71 02.94 03.09 03.31 03.54 03.75 03.99 04.23

INBR 81 R

26600.35 00.47 00.59 00.72 00.86 01.00 01.15 01.30 01.45 01.61 01.79 01.95 02.13 02.32 02.51 02.71

P

26600.12 00.01 599.91

R 26600.35 00.47 00.59 00.72 00.86 01.00 01.15 01.30 01.45 01.61 01.79 01.95 02.13 02.32 02.51 02.71

02;94 03.09

02.94 03.09

03.31 03.54 03.75 03.99 04.37 04.61 04.85 05.10 05.36 05.61 05.68 06.14 06.43 06.69 07.00 07.27 07.58 07.88 08.18 08.51 08.82 09.14 09.47 09.81 10.15 10.49 10.84 11.20 11.56 11.93 12.30 12.68 13.06 13.45 13.84 14.24 14.65 15.05 15.47 15.90 16;32 16.75 17.19 17.62 18.08 18.55 19.00 19.46

03.31 03.54 03.75 03.99 04.23 04.46 04.70 04.96 05.22 05.47 05.74 06.01 06.28 06.57 06.84 07.13 07.43 07.72 08.04 08.35 08.66 08.99 09.31 09.64 09.98 10.32 10.67 11.02 11.38 11.75 12.11 12.49 12.86 13.25 13.64 14.03 14.44 14.84 15.25 15.67 16.09 16.51 16.95 17.39 17.82 18.27 18.72 19.17

99.91 600.01 00.12 00.23 00.35 00.47 00.59 00.72 00.85 01.00 01.15 01.30 01.45 01.61 01.79 01.95

02.13 02.32 02.51 02.71 02.94 03.09

03.31 03.54 03.75 03.99 04.23

,40+-X0+

AND H-X0+

SYSTEMS

409

OF InBr

TABLE I-Continued INBR 81

INBR 79 J

P

R

P

66 67

04.46 04.70 04.96 05.22 05.47 05.74 06.01 06.28 06.56 06.84 07.13 07.43 07.72 08.04 08.35 08.65 08.99 09.31 09.64 09.98 10.32 10.67 11.02 11.38 11.75 12.11 12.49 12.86 13.25 13.64 14.03 14.44 14.84 15.25 15.67 16.09 16.50 16.95 17.39 17.02 10.27 18.72 19.17 19.63 20.10 20.58 21.06 21.54 22.03 22.52 23.02 23.52 24.03 24.54 25.07 25.59 26.12 26.65 27.19 27.73 28.20 20.03 29.39 29.96 30.53 31.10

19.94 20.40 20.88 21.37 21.87 22.37 22.86 23.37 23.88 24.39 24.91 25.44 25.97 26.51 27.06 27.61 28.16 28.71 29.28 29.84 30.41 31.00 31.58 32.17 32.77 33.38 33.98 34.60 35.24 35.85 36.47 37.10 37.74 38.38 39.02 39.67 40.32 40.98 41.64 42.31 42.99 43.67 44.35 45.03 45.72 46.43 47.13 47.84 48.55 49.27 50.00 50.72 51.46 52.19 52.94 53.69 54.44 55.21 55.97 56.73 57.50 58.27 59.06 59.88 60.68 61.49

04.37 04.61 04.85 05.10 05.36 05.61 05.88 06.14 06.43 06.69 07.00 07.27 07.58 07.88 08.18 08.51 08.82 09.14 09.47 09.81 10.15 10.49 10.84 11.20 11.56 11.93 12.30 12.68 13.06 13.45 13.84 14.24 14.65 15.05 15.47 15.89 16.31 16.75 17.19 17.62 18.01 18.45 18.90 19.38 19.84 20.28 20.77 21.25 21.71 22.18 22.69 23.20 23.70 24.22 24.72 25.23 25.75 26.29 26.80 27.32 27.88 20.44 28.99

5: 70 71 72 73 74 75 76 77 10 i;: 81 :: :: 86 a7 88 89 90 91 92 93 E 96 ii 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131

29.55

30.10 30.72

R 19.63

20.10 20.58 21.06 21.54 22.03 22.52 23.02 23.52 24.03 24.54 25.07 25.59 26.12 26.65 27.19 27.73 20.28 28.83 29.39 29.96 30.53 31.10 31.68 32.27 32.86 33.45 34.05 34.65 35.24 35.85 36.47 37.10 37.74 38.38 39.02 39.67 40.32 40.98 41.64 42.31 42.99 43.67 44.35 45.03 45.72 46.43 47.13 47.04 48.55 49.27 50.00 50.72 51.46 52.19 52.94 53.69 54.44 55.21 55.97 56.73 57.50 58.27 59.06 59.84

60.62

VEMPATI

410

AND JONES

TABLE I-Continued INBR 81

INBR 79 J 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 165

P

R

P

R

31.68 32.27 32.86 33.45

62.30 63.11 63.94 64.76 65.59 66.42 67.26 68.10 68.94

31.26 31.82

61.42 62.21 63.01 63.82 64.63 65.46 66.28 67.11 67.94 60.70 69.63 70.49 71.34 72.19 73.05 73.93 74.80 75.68 76.56 77.44 78.32 79.23 80.15 81.04 81.96 82.87 03.79 04.72 85.65 86.58 87.51 08.46 90.39

69.79

70.65 71.51 72.38 73.25 74.13 75.01 75.09 76.78 77.67 70.57 79.48 80.39 81.31 02.22 83.15 84.09 85.00 85.96

32.39

32.99 33.57 34.17 34.79 35.39 36.02

from the isotope effects, both single headed (P heads) and double headed (P and Q heads) band systems were observed, which have been assigned (I) to the AOf-X0+ and B 1-X0+ transitions, respectively. We were able to record approximately 10 bands of each of the sequences with Av = -2, - 1, 0, 1,2, and 3 of each system. A peculiar feature of the spectrum is that while the bands are shaded to the violet, the sequences extend to the red. A “head of heads” (7) is often found to be formed in the vicinity of the shortest wavelength band of the sequence. This, in conjunction with the overlap of isotopic bands results in an extremely dense spectrum. So dense, that the 1-O and O-l bands in both systems remain unresolved even at very high J values. However, the Av = 0 sequences are not so well developed, and analysis of these bands is possible. Another fortuitous coincidence is the negligible separation between the origins of the two isotopic bands in this sequence. The separations are calculated to be less than 0.02 cm-‘, the limit of accuracy of the measurements. The O-O bands of the A-X system are shown in Fig. 1. The lines of the R branches of the isotopes In’iBr (Rl) and In79Br (R2) are strong and can be identified almost from the origin. The weaker lines of the P branch corresponding to In”Br not overlapped by other lines of the band are shown in the figure (for J = 106 to J = 145). The P branch of In79Br has been found to merge with the R branch of In*‘Br. The O-O band of the B-X system is shown in Fig. 2. Six branches, Pl , R 1, and Ql of In*‘Br and P2, R2, and Q2 of In79Br have been identified in the figure.

,40+-X0+

AND Bl-X0+ ROTATIONAL

SYSTEMS

OF InBr

411

ANALYSIS

Before proceeding with the analysis, the line positions were generated from the constants of Nampoori and Pate1 (4) and were compared with those measured in the current work. The agreement is not satisfactory even for rotational lines at high J which should have been resolved according to Nampoori and Patel’s data (4). The first step in the analysis consisted of identifying the different isotopic branches. This was accomplished by fitting the successive differences between the lines of an R branch to the equation Au = v(m + 1) - v(m) = a + bm + cm2

(1)

Assuming, v(m) = v. + (B: + BE)m + (B: - B’: - 0:

+ D’:)m2 - 2(D: - D:)m3

(2)

for an arbitrary numbering “m,” it can be shown that b = 2(BL - II’:), to a good approximation. Noting that the ratio of the values of b for different isotopes is equal to p2, the different isotopic branches may be readily and correctly identified. This was rather easy in the case ofthe O-O band of the A-Xsystem, since we have no Q branches. For the O-O band of the B-X system the same method as well as the frequency of crossing of the R and Q lines and the number of lines between successive crossings of a given pair of branches were used in correctly identifying the Q and R branches. Since the ground state rotational constants for InBr are accurately known (5) from microwave spectroscopy, the absolute numbering of the R-branch lines was determined using the equation m=

Au - (b + 2B:) b

(3)

where b is determined from fits of Au to Eq. (1). Similar equations were used for the Q branches. Once the absolute J numbering was determined, the band origins were readily located. In the case of the O-O band of the B system, the Q branch offered an alternative method of determining the origin. From the known and calculated rotational constants, P lines in the O-O bands of both the A-X and B-X systems were calculated using the equation v(m) = v. + (B: + B’:)m + (B: - B’: - D\ + D6)m2 - 2(DL + D’:)m3 - (D: - D6)m4.

(4)

For these calculations B$ is obtained from microwave data and Bb is calculated from the relationship Bb - B$ = f b, where b is from Eq. (1); Db and D$ are obtained from Kratzer’s relation D = 4B3/u2. As can be Seen in Tables I and II, very few separate P lines were obtained in either band system. However, where possible the numbering has been further verified by comparing the combination differences obtained for the lower state X0+ (V = 0) in each of the systems. Tables I and II and Figs. 1 and 2 present a complete listing of the frequencies of the lines identified for the O-O bands of the A-X and B-X systems of InBr. As may be noted in Table II, most of the P and R lines between the origin and approximately 27 400 cm-’ are found to be overlapped by Q lines.

412

VEMPATI AND JONES TABLE II Wavenumbers of the Lines Identified in the O-O Band of the H-X0+ INBR J

P

P 3 :6 ll9

79 0

27381.53 81.43 81.34 81.25 81.16 81.08

11 12 13 14 15 16 17

5: 56 57 si 60 61

81.08 81.16 81.25 81.34 81.43 81.53 81.63 81.74 81.85 81.98 82.10 82.23 82.37 82.50 82.67 82.79 82.99 83.12 83.36 83.48 83.63 84.06 84.22

:3 fS 85.25 It! f: 70 71

86.42 86.65

:3 :"s 76 77 78 ifi 81 02

87.15 87.43 87.68 87.94

89.11 89.40

R

27381.85 81.98 82.10 82.23 82.37 82.50 82.67 82.79 82.99 83.12 83.25 83.48 83.63 83.79 84.06 84.22 84.38 84.56

10

38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53

INBR

27388.70 88.97 89.24 89.52 89.80 90.07 90.36 90.66 90.96 91.28 91.59 91.92 92.23 92.55 92.88 93.21 93.56 93.91 94.27 94.63 94.98 95.35 95.72 96.09 96.48 96.85 97.24 97.65 98.05 90.47 98.90

90.66 90.96 91.28 91.59 91.92 92.40 92.73 93.04 93.39 93.73 94.08 94.43 94.79 95.24 95.63 96.09 96.48 96.85 97.24 97.64 98.05 98.47 98.90 99.34 99.79 400.26 00.69 01.13 01.57 02.02 02.48 02.99 03.39 03.93 04.41 04.90 05.41 05.91 06.42 06.91 07.43 07.96 08.49

P

Transition (cm-‘) 81

Q

27381.85 81.98 82.10 82.23 82.37 82.50 82.67 82.79 82.99 83.12 83.25 83.48 83.63 83.79 84.06 84.22 84.38 84.56

27381.53 81.43 81.34 81.25 81.16 81.08

81.08 81.16 81.25 81.34 81.43 81.53 81.63 81.74 81.85 81.98 82.10 82.23 82.37 82.50 82.67 82.79 %-E 83136 83.48 83.63 83.79

84.56 84.74

85.64 85.87 86.09 86.31

87.35 87.59 87.84 88.19 88.44 88.70 88.97

R

27388.84 :x 89167 89.97 90.25 90.52 90.83 91.13 91.45 91.76 92.08 92.40 92.73 93.04 93.39 93.73 94.08 94.43 94.79 95.15 95.52 95.89 96.26 96.63 97.01 97.41 97.81 98.22 98.63

90.21 90.52 90.83 91.16 91.49 91.81 92.16 92.50 92.85 93.21 93.56 93.91 94.27 94.63 94.98 95.43 95.89 96.26 96.63 97.01 97.41 97.81 98.22 98.63 99.04 99.60 99.85 400.40 00.84 01.28 01.73 02.19 02.66 03.14 03.61 04.10 04.57 05.09 05.58 06.08 06.57 07.07 07.58 08.09

AO+-X0+ AND Bl-X0+

413

SYSTEMS OF InBr

TABLE II-Continued INBR 81

INBR 79 J

P

89.67 89.97

SB: ii89 90

91

90.66 90.96 91.28 91.59 91.92 92.23

9932 z"5 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148

94.43 94.79 95.15 95.52 95.89 96.26 96.63 97.10 97.52 97.93 98.34 98.77 99.18 99.61 400.12 00.55 00.98 01.42 01.86 02.32 02.77 03.23 03.70 04.17 04.78 05.25 05.73 06.22 06.71 07.21 07.71 08.21 08.73 09.24 09.77 10.28 10.88 11.43 11.96 12.52 13.07 13.65 14.21 14.78 15.35 15.93 16.53

Q

99.29 99.70 400.12 00.55 00.98 01.42 01.86 02.32 02.77 03.23 03.70 04.17 04.65 05.09 05.58 06.08 06.57 07.07 07.58 08.09 08.60 09.13 09.65 10.17 10.66 11.21 11.76 12.31 12.86 13.42 13.99 14.55 15.11 15.68 16.26 16.85 17.44 18.03 18.63 19.25 19.85 20.47 21.09 21.71 22.32 22.96 23.60 24.23 24.87 25.51 26.16 26.82 27.48 28.15 28.81 29.49 30.17 30.85 31.53 32.22 32.92 33.62 34.33 35.04 35.76 36.47

R

09.02 09.55 10.09 10.66 11.21 11.76 12.31 12.86 13.42 14.09 14.55 15.19 15.77 16.35 16.94 17.53 18.12 18.69 19.43 20.05 20.66 21.29 21.92 22.56 23.20 23.86 24.53 25.18 25.83 26.49 27.17 27.85 28.52 29.20 29.89 30.58 31.28 31.98 32.69 33.41 34.13 34.85 35.58 36.31 37.04 37.86 38.58 39.34 40.09 40.83 41.59 42.42 43.18 43.95 44.72 45.50 46.29 47.08 47.88 48.68 49.52 50.34 51.15 51.97 52.81 53.64

P

90.52 90.83

91.13 91.45 91.76

93.91 94.27 94.63 94.98 95.35 95.71 96.09 96.48 96.85 97.24 97.64 98.07 98.48 98.90 99.34 99.79 400.26 00.69 01.13 01.57 02.02 02.48 02.94 03.39 03.93 04.41 04.90 05.41 05.91 06.42 06.91 07.43 07.85 08.36 08.86 09.38 09.90 10.45 10.99 11.54 12.08 12.64 13.19 13.75 14.32 14.88 15.45 16.03 16.61 17.20 17.79 18.39 18.98

Q

99.04 99.44 99.85 400.26 00.69 01.13 01.57 02.02 02.48 02.94 03.39 03.84 04.31 04.78 05.25 05.73 06.22 06.71 07.21 07.71 08.21 08.73 09.24 09.77 10.28 10.81 11.33 11.87 12.42 12.98 13.53 14.09 14.66 15.1.9 15.77 16.35 16.94 17.53 18.12 18.69 19.25 19.85 20.47 21.09 21.71 22.32 22.96 23.60 24.23 24.87 25.51 26.16 26.82 27.48 28.15 28.81 29.49 30.17 30.85 31.53 32.22 32.92 33.62 34.33 35.04 35.76

R

08.60 09.24 09.77 10.28 10.81 11.33 11.87 12.42 12.98 :x3 14:66 15.35 15.83 16.44 17.04 17.64 18.24 18.85 19.43 20.05 20.66 21.29 21.92 22.56 23.20 23.86 24.53 25.18 25.83 26.49 27.17 27.85 28.52 29.20 29.89 30.58 31.28 31.98 32.69 33.41 34.13 34.85 35.58 36.31 37.04 37.75 38.49 39.24 39.98 40.75 41.51 42.29 43.05 43.82 44.59 45.37 46.15 46.93 47.71 48.53 49.36 50.17 51.01 51.82 52.64

414

VJZMPATI AND JONES TABLE II-Continued INBR 79 J 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179

P

INBR al

Q

R

37.19 37.95 38.69

54.47 55.32 56.17 57.02 57.88 58.73 59.60 60.47 61.34 62.22 63.10

39.44

40.18 40.93 41.68 42.42 43.18 43.95 44.72 45.50 46.29 47.08 47.88 48.68 49.44 50.23 51.01 51.82 52.64 53.47 54.28 55.11 55.95 56.79 57.63 58.48 59.33

60.18 61.04

180

61.91

181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213

62.75 63.60 64.49 65.36 66.23 67.12 68.01 68.91 69.80 70.70 71.59 72.51 73.42 74.32 75.26 76.18 77.11 78.04 78.97 79.91 80.86 81.80 82.75 83.70 84.66 85.62 86.59 87.53 88.51 89.49 90.49 91.47 92.47

P

Q 36.47 37.19 37.86 38.58 39.34 40.09

40.83 41.59 42.29

43.05 43.82

63.99

44.59

64.88 65.76 66.65 67.56 68.47 69.42 70.32 71.23 72.15 73.06 74.00 74.95 75.89 76.83 77.78 78.73 79.69 80.64 81.61 82.59 83.55 84.54 85.51 86.50 87.53 88.51 89.49 90.49 91.47 92.47 93.47 94.45 95.55

45.37 46.15 46.93 47.71 48.52 49.27 50.05 50.85 51.66 52.47 53.28 54.09 54.91 55.74 56.56 57.39 58.23 59.07 59.91 60.75 61.61 62.47 63.33 64.18 65.05 65.93 66.81 67.69 68.56 69.42 70.32 71.23 72.15 73.06 74.00 74.86 75.78 76.70 77.61 78.55 79.47 80.40 81.35 82.29 83.23 84.18 85.13 86.10 87.01 87.99 88.97 89.94 90.93

96.57 97.60 98.64

R 53.47 54.28 55.11 55.95 56.79 57.63 58.48 59.33 60.18 61.04 61.91 62.81 63.71 64.58 65.47 66.35 67.25 68.15 69.05 69.97 70.86 71.78 72.72 73.63 74.56 75.51 76.43 77.37 78.30 79.25 80.20 81.16 82.13 83.09 84.06 85.02 86.00 87.01 87.99 88.97 89.94 90.93 91.93 92.93 93.93 94.92 95.98 96.99 98.01 99.03 500.07

TABLE II-Continued INBR 81

INBR 79 P

J 214 215 216 217 218 219 220 221 222

R

Q

P

R

Q 93.47 94.45 95.45 96.44 97.45

91.93 92.93 93.93 94.92 95.85 96.83 97.85 98.86 99.85

TABLE III Rotational Constants Calculated for the AO+and Bl States of InBr State

-x0+

Be*

0.0557099(7)

0.0548944(7)

B.

0.0556147(7)

0.0548013(7)

Do x lo***

1.39(3)

1.42(3)

27 381.710(4)

27 381.705(4)

0.0025358(4)

O.D024996(5)

EL from

Q-branches

v. AB

2.32(l)

2.26(l)

0.0581505(11)

0.0573009(12)

1.65(3)

1.62(3)

27 381.742(6)

27 381.745(4)

AB

0.0025325(15)

O.D024925(8)

AD x 10'

2.18(7)

1.97(4)

Be 0

0.0581472(22)

D.D572938(15)

1.64(3)

1.59(3)

0.05814885(16)

0.05729735(14)

1.65(3)

1.61(3)

AD x

10'

5: D; x 10' from

P and

R branches

u.

DE x lo8 Average

Values

BO Do x lo8 AO+ -

26 600.250(3)

26 600.257(4)

0.0026995(8)

0.0026524(g)

nD x 10'

2.34(4)

1.78(4)

B

0.0583142(15)

0.0574537(16)

1.65(3)

1.57(3)

vO AB

0

Do x lo8

*

Ref

(5) gives

calculated **

Do values

values

from

of Be and

isotopic

obtained

ae for

In7’Br.

Those

of

In81Br

relations.

in present

work 415

from

combination

differences.

are

416

VEMPATI AND JONES TABLE IV Summary of Molecular Constants for “51n79Brand “51n*‘Br Statea

b

Te

Cl

34 oooc

61

27 380.5d

AO+

26 597.4’

x0+

Note:

The upper and respectively. 'a' or

Bl(3~l);

and

values

weze

calculated Vertical

225.0

1.53

0.05814ge

1.b5e

223.3

1.51

0.057297e

l.ble

229.2

1.42

0.058314e

1.b5e

227.5

1.40

0.057454=

1.57e

223.0

0.58

0.055709gf

0.0001903f

1.42

221.4

0.57

0. 0548944f

0.00018bZf

1.39

voo

using

Recalculated

from

Values

given

are

Be and

ae for

for

In7'Br

isotopic from voo,

are

states

correspond

In7'Br

as follows

26 600.26

and

In81Br,

XO'(lz+);

isotopic

in Ref

v = 0; fluctuation

using

are

given

(2).

Those

for

In81Br

are

relations.

we and

for u = 0 of the

In7'Br

using

these

to

27 381.73

Cl('n).

transition

calculated

ae

lowerentries,whereqiven,correspond

'b' terminology,

A0+(3no+);

we

1080e

We%

35 053

0

In case

b

we

given

bands

with

various

v'

(2).

~eze.

state.

in Ref.

(5).

Those

for

the

In81Br

are

relations.

In order to extend and verify the identification of P and R lines between about J = 70 and J = 10, line positions were calculated using molecular constants which were continually refined on the basis of combination differences. Where measured, observed lines that fit within ?O. 1 cm-’ have been included in Table II. The occasional blank in the P branch indicates that the nearest measured line was more than 0.1 cm-i from the predicted position, presumably as a result of extreme overlap by a dense line. The rotational constants for the upper states were finally determined as differences (B: - B’:) or (DL - DE) from R(J -

1) + P(J) = 2~ + 2(B: - B’:)J2 - 2(D: - D’:)J2(J2 + 1)

MJ) = v. + (B: - B;)J(J

+ 1) - (D: - D’:)J2(J + 1)2.

(5)

(6)

Since an accurate value of DE is not available, the value obtained from A2F”(J) = (48’: - 6D:)(J

for the B-X (O-O) band was used.

+ 1) - 8D;(J

+ f)’

(7)

AO+-X0+ AND /31-X0+ SYSTEMS OF InBr

417

The differences AB = Bb - B$ and AD = Db - DZ as determined from Eqs. (5) and (6) are frequently more accurate than the constants obtained from combination differences (8). Since microwave studies (5) provide accurate values of the rotational constants B, = 0.0548944 cm-‘, and LY,= 0.0001862 cm-‘, for the ground state, we can obtain B values for the upper states accurate to five figures from B$ + AB. The values of AB, AD, and v. as calculated from Eqs. (5) and (6) are given in Table III. As can be seen, slightly different values for AB are obtained depending on whether Eq. (5) (R-P branches) or Eq. (6) (Q branch) is used. If these differences were significant, one could calculate a value of the combination defect c and the ordering of the e and flevels of the Bl state. Unfortunately, the size of the combination defects predicted by these values of B, and Bfare considerably larger than those calculated from combination differences at high J. We must conclude that the individual values of B, and Br are not significant and an average value of B. is presented for the B 1 state. Table IV presents a complete summary of the rotational constants for the two isotopic species 1’51n79Brand “sIn8LBr. ACKNOWLEDGMENTS We gratefully acknowledge financial support from the Natural Sciences and Engineering Research Council of Canada in the form of an operating grant to W.E.J. We are also indebted to Dr. D. A. Ramsay of the National Research Council of Canada, Ottawa, for permission to use the 8.8-m spectrograph and to Mike Bamett for his excellent and untiring support during the photographing of the spectra. RECEIVED:

January 2 1, 1986 REFERENCES

1. M. WEHRLIAND E. MIESCHER,Helv. Phys. Acta 6,457-458 (1933). 2. M. WEHRLIAND E. MIESCHER,Helv. Phys. Acta I, 298-330 (1934). 3. A. LAKSHMINARAYANA AND P. B. V. HARANATH,Indian J. Phys. 44,504-5 10 (1970). 4. V. P. N. NAMFQORIAND M. M. PATEL, Current Sci. 45,369-370 (1976). 5. A. H. BARRETTAND M. MANDEL, Phys. Rev. 109,1572-1589 (1958). 6. “Handbook of Chemistry and Physics,” 46th ed., The Chemical Rubber Co., Cleveland, Ohio, 1965. 7. G. HERZBERG,“Molecular Spectra and Molecular Structure,” Vol. 1, “Spectra of Diatomic Molecules,” 2nd ed.. pp. 159-161, Van Nostrand, Princeton, N.J., 1950. 8. Ref. (7), pp. 187-188.