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iodine bromide

Constants of diatomic molecules

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Data compilation copyright by the U.S. Secretary of Commerce on behalf of the U.S.A. All rights reserved.

Data compiled by: Klaus P. Huber and Gerhard H. Herzberg

Data collected through January, 1977

Symbols used in the table of constants
State electronic state and / or symmetry symbol
Te minimum electronic energy (cm-1)
ωe vibrational constant – first term (cm-1)
ωexe vibrational constant – second term (cm-1)
ωeye vibrational constant – third term (cm-1)
Be rotational constant in equilibrium position (cm-1)
αe rotational constant – first term (cm-1)
γe rotation-vibration interaction constant (cm-1)
De centrifugal distortion constant (cm-1)
βe rotational constant – first term, centrifugal force (cm-1)
re internuclear distance (Å)
Trans. observed transition(s) corresponding to electronic state
ν00 position of 0-0 band (units noted in table)
Diatomic constants for 127I79Br
62000 - 77000 1           
Donovan and Robertson, 1972
J 65793 [267] H         J larrow X 65792 H
Donovan and Robertson, 1972
H (64092) (290) H         (H larrow X) V (64103) 2 H
missing citation
G (60877) (280) H         (G larrow X) V (60883) 2 H
missing citation
F 56349 [310] H         F lrarrow X 3 V 56370 H
Cordes and Sponer, 1932; Haranath and Rao, 1957; missing citation
E 51677 [314] H         E lrarrow X 4 V 51700 H
Cordes and Sponer, 1932; Haranath and Rao, 1957; missing citation
D (38849) 90.2 H 0.15        D rarrow A 5 R (26476) H
Haranath and Rao, 1957; Venkateswarlu and Verma, 1958
Diffuse emission bands from 19000 to 29000 and 36000 to 43000 cm-1.
Asundi and Venkateswarlu, 1947
Fragments of three emission band systems near 18600, 22300, and 24500 cm-1.
Venkateswarlu and Verma, 1958
           (B' larrow X) 
Seery and Britton, 1964; Donovan and Husain, 1968
           (B larrow X) 
Seery and Britton, 1964; Donovan and Husain, 1968
B' 0+  (60) 6         B' larrow X R 
Brown, 1932; missing citation
B 3Pi0+ 16168 142.5 Z 2.57 7 -0.11 0.0432 8 9 0.00053  D2 = 2.2E-8  2.83 B larrow X R 16104 8 Z
Brown, 1932; Selin and Soderborg, 1962
A 3Pi1 12350 138 1.7 10 -0.02       A lrarrow X 11 R 12285 12
Brown, 1932; missing citation; missing citation
X 1Sigma+ 0 268.640 13 Z 0.8140 -0.00177 0.05683252 14 0.00019690 -0.00000047 (1.02E-8)  2.468989 15  
Holzer, Murphy, et al., 1970
Microwave sp. 16
Tiemann and Moller, 1975


1Fragments of several Rydberg series converging to X 2Pi3/2 and 2Pi1/2 of IBr+. Tentative assignments. The three strongest series join on to E, H, J, resp..
2 Donovan and Robertson, 1972 give 63573 and 60624 as 0-0 bands of these systems [called F-X, and E-X, respectively, by Donovan and Husain, 1968]; the band intervals seem to fit better with the choice made here.
3Formerly called D-X.
4Formerly called C-X. An extended resonance series excited by the 1849 Å Hg line Loomis and Allen, 1929, may originate from a high level (v'=8?) of E.
5The analysis of this system was based on the old Brown, 1932, numbering of the A-X system. The shift in the numbering by one unit established by Selin, 1962, means either that the v"=0 column has to be omitted from the D-A Deslandres table of Venkateswarlu and Verma, 1958, and thus v00 = 26340, or that the DeltaG" values of Venkateswarlu and Verma, 1958 are systematically higher than those of Brown, 1932 and Selin, 1962. Our choice of v00 [from Venkateswarlu and Verma, 1958] corresponds to the latter alternative.
6Potential well resulting from an avoided intersection of a repulsive 0+ state with B 3Pi0+; see Brown, 1932, Selin, 1962, 2, Child and Bernstein, 1973, Faist and Bernstein, 1976. 20
7From v=2,3,4, including data for I81Br.
8Extrapolated from data with v' = 2,3,4.
9Bands with v'=5 are diffuse, presumably because of predissociation into the intersecting 0+ state from 2P3/2 + 2P3/2. Higher levels are not observed; see, however, B' 0+.
10The constants represent the levels v'=5...16 Selin, 1962, Clyne and Coxon, 1967, vibrational numbering confirmed by the observed isotope shifts Selin, 1962. Levels have been identified up to v = 43, convergence at 14660 cm-1.
11An extended magnetic rotation spectrum has been observed by Eberhardt, Cheng, et al., 1959.
12Extrapolated from data with v' geq 5.
13These vibrational constants from laser-excited fluorescence data Weinstock, 1976, differ only very slightly from the earlier constants of Selin, 1962.
14missing note
15Raman sp. 23
16Iodine and bromine eqQ values for v=0,1,2.
17From the convergence of A 3Pi1; see 10.
18Vertical potential from the photoelectron spectrum Potts and Price, 1971; vibrational structure not resolved. From the temperature dependence of the photo-ion yield curve in the threshold region Dibeler, Walker, et al., 1971, conclude that the adiabatic potential is probably 9.79 eV.
19Absorption in the continuum at v leq ~33000 cm-1 produces predominantly excited Br 2P1/2 atoms [diabatic dissociation, see Donovan and Husain, 1968]. By contrast, absorption at 18830 cm-1, i.e. closer to the region of the avoided crossing of the two 0+ curves, leads mainly to ground state Br 2P3/2 atoms [adiabatic dissociation Busch, Mahoney, et al., 1969]. See also the discussion in Coxon, 1973.
20Vibrational levels of this state, some sharp, others diffuse, have been observed Brown, 1932 from 17215 cm-1 (relative to X 1Sigma, v=0) to 18315 cm-1, i.e. to within 30 cm-1 of the limit I(2P3/2) + Br(2P1/2). The vibrational numbering is still undecided; Selin, 1962, 2, following Brown, 1932 assigns v=8 to the lowest observed level, Child and Bernstein, 1973 suggest v=2, while Couillaud, Ducasse, et al., 1976 prefer v=5. Narrow J regions of a number of levels have been analyzed by Selin, 1962, 2; Bv varies from 0.03226 (I81Br) for v=8 in the numbering of Selin, 1962, 2 to 0.0229 (I79Br) for v=27. The levels v=25 of I81Br and v=26 of I79Br have also been observed in the magnetic rotation spectrum Eberhardt, Cheng, et al., 1959.
21Bv and Dv values from v=9 to 30 are listed by Selin, 1962. The Lambda-type doubling constant q [~B(R,P)-B(Q)] for v=14 is +10E-6 and increases to 42E-6 for v=29.
22Microwave value of Tiemann and Moller, 1975, in good agreement with the less accurate values from the electronic spectrum Selin, 1962, Weinstock, 1976. An earlier microwave value by Jaseja, 1960 was clearly erroneous.
23Resonance Raman spectra in argon matrices Wight, Ault, et al., 1975.


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Data compilation copyright by the U.S. Secretary of Commerce on behalf of the U.S.A. All rights reserved.

Donovan and Robertson, 1972
Donovan, R.J.; Robertson, P.J., Vacuum ultraviolet spectrum of IBr, Spectrosc. Lett., 1972, 5, 361. [all data]

Cordes and Sponer, 1932
Cordes, H.; Sponer, H., Die molekulabsorption der gemischten halogenmolekule im vakuumultraviolett. II. Mitteilung, Z. Phys., 1932, 79, 170. [all data]

Haranath and Rao, 1957
Haranath, P.B.V.; Rao, P.T., Emission spectra of mixed halogens. Part II: IBr and BrCl, Indian J. Phys., 1957, 31, 368. [all data]

Venkateswarlu and Verma, 1958
Venkateswarlu, P.; Verma, R.D., The emission spectrum of iodine bromide excited in the presence of argon. Part I. The band system in the regions 5425-5360 Å, 4520-4415 Å and 4120-4010 Å, Proc. Indian Acad. Sci. Sect. A, 1958, 47, 150. [all data]

Asundi and Venkateswarlu, 1947
Asundi, R.K.; Venkateswarlu, P., On continous emission bands of ICl and IBr, Indian J. Phys., 1947, 21, 76-82. [all data]

Seery and Britton, 1964
Seery, D.J.; Britton, D., The continuous absorption spectra of chlorine, bromine, bromine chloride, iodine chloride, and iodine bromide, J. Phys. Chem., 1964, 68, 2263. [all data]

Donovan and Husain, 1968
Donovan, R.J.; Husain, D., Photochemical studies of IBr, ICl and BrCl by kinetic spectroscopy in the vacuum ultra-violet, Trans. Faraday Soc., 1968, 64, 2325. [all data]

Brown, 1932
Brown, W.G., Absorption spectrum of iodine bromide, Phys. Rev., 1932, 42, 355. [all data]

Selin and Soderborg, 1962
Selin, L.-E.; Soderborg, B., Analysis of the absorption spectrum of IBr. II. Rotational analysis of the red bands, Ark. Fys., 1962, 21, 515. [all data]

Holzer, Murphy, et al., 1970
Holzer, W.; Murphy, W.F.; Bernstein, H.J., Resonance Raman effect and resonance fluoroscence in halogen gases, J. Chem. Phys., 1970, 52, 399. [all data]

Tiemann and Moller, 1975
Tiemann, E.; Moller, Th., Das Rotationsspektrum des IBr, Z. Naturforsch. A, 1975, 30, 986. [all data]

Loomis and Allen, 1929
Loomis, F.W.; Allen, A.J., Ultra-violet fluorescence of IBr and I2, Phys. Rev., 1929, 33, 639. [all data]

Selin, 1962
Selin, L.-E., Analysis of the absorption spectrum of IBr. I. Rotational analysis of the near infrared bands, Ark. Fys., 1962, 21, 479. [all data]

Selin, 1962, 2
Selin, L.-E., Analysis of the absorption spectrum of IBr. III. Rotational analysis of the visible bands, Ark. Fys., 1962, 21, 529. [all data]

Child and Bernstein, 1973
Child, M.S.; Bernstein, R.B., Diatomic interhalogens: systematics and implications of spectroscopic interatomic potentials and curve crossings, J. Chem. Phys., 1973, 59, 5916. [all data]

Faist and Bernstein, 1976
Faist, M.B.; Bernstein, R.B., Computational study of elastic and electronically inelastic scattering of Br by ground state I atoms: role of potential curve crossing, J. Chem. Phys., 1976, 64, 2971. [all data]

Clyne and Coxon, 1967
Clyne, M.A.A.; Coxon, J.A., The emission spectra of Br2 and IBr formed in atomic recombination processes, J. Mol. Spectrosc., 1967, 23, 258. [all data]

Eberhardt, Cheng, et al., 1959
Eberhardt, W.H.; Cheng, W.-C.; Renner, H., The magnetic rotation spectrum of ICl and IBr, J. Mol. Spectrosc., 1959, 3, 664. [all data]

Weinstock, 1976
Weinstock, E.M., The laser-induced fluorescence of IBr79, J. Mol. Spectrosc., 1976, 61, 395. [all data]

Potts and Price, 1971
Potts, A.W.; Price, W.C., Photoelectron spectra of the halogens and mixed halides ICI and lBr, J. Chem. Soc. Faraday Trans., 1971, 67, 1242. [all data]

Dibeler, Walker, et al., 1971
Dibeler, V.H.; Walker, J.A.; McCulloh, K.E.; Rosenstock, H.M., Effect of hot bands on the ionization threshold of some diatomic halogen molecules, Intern. J. Mass Spectrom. Ion Phys., 1971, 7, 209. [all data]

Busch, Mahoney, et al., 1969
Busch, G.E.; Mahoney, R.T.; Morse, R.I.; Wilson, K.R., Photodissociation recoil spectra of IBr and I2, J. Chem. Phys., 1969, 51, 837. [all data]

Coxon, 1973
Coxon, J.A., Chapt. 4. Low-lying electronic states of diatomic halogen molecules in Molecular Spectroscopy. Volume 1, Barrow,R.F.; Long,D.A.; Millen,D.J., ed(s)., The Chemical Society, Burlington House, London, W1V 0BN, 1973, 177-228. [all data]

Couillaud, Ducasse, et al., 1976
Couillaud, B.; Ducasse, A.; Garrido, L.; Joly, F., Courbes d'energie potentielle des etats B(3«PI»o+) et Y(0+) de IBr, J. Phys. B:, 1976, 9, 2091. [all data]

Jaseja, 1960
Jaseja, T.S., Microwave spectrum of IBr and the determination of the molecular and nuclear parameters, J. Mol. Spectrosc., 1960, 5, 445. [all data]

Wight, Ault, et al., 1975
Wight, C.A.; Ault, B.S.; Andrews, L., Laser-induced fluorescence and resonance Raman spectra of interhalogen diatomics isolated in inert matrices at 12 K, J. Mol. Spectrosc., 1975, 56, 239. [all data]


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