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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 December, 1976

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 D81Br+
A 2Sigma+ 28421.2 999.25 Z 19.12  3.0241 1 2 0.0894  1.10E-4  1.6842 A rarrow X R 28054.4 3 Z
Marsigny, Lebreton, et al., 1968; Lebreton, 1973
X 2Pii 0 4 1734.36 5 Z 22.18 6  4.0877 7 0.0848  0.870E-4  1.4486  


1Spin splitting constant gamma(v=0) = 1.068.
2Only v'=0,1,2 observed in emission; breaking-off for N'>12 of v'=2 Haugh and Bayes, 1971. In the photoelectron spectrum v'=0...8 have been observed Delwiche, Natalis, et al., 1973 but the bands with v'=6,7,8 are very broad indicating strong predissociation beginning at the same energy as in HBr+.
3Referring in the lower state to the zero point of the Hill-Van Vleck formula.
4A0 = -2651.45, A1= -2649.54, ...
5missing note
6missing note
7Lambda-type doubling constants (p ~ 1.05) in Lebreton, 1973.
8From the predissociation in the A 2Sigma+ state Haugh and Bayes, 1971; see 11. D00(HBr) + I.P.(Br) - I.P.(HBr) = 3.902 eV.
9From isotope relations and the constants for DBr+ Lebreton, 1973. Barrow and Caunt, 1953 derive DeltaG(1/2) = 1328.7 from band origins.
10Spin splitting constant gamma(v=0)= 2.105; small variation with N.
11Only v'=0 and 1 observed in emission. Haugh and Bayes, 1971 have observed a sharp breaking-off at N'=12 for v'=1 and a less distinct breaking-off at N'=21 for v'=0 yielding a dissociation limit at 31407 ± 20 cm-1. In the photoelectron spectrum of HBr Delwiche, Natalis, et al., 1973 the bands with v'=2 and 3 are as narrow as those with v'=0 and 1 but bands with v'«gte»4 are strongly broadened indicating strong predissociation (lifetime tau ~ 2E-14 s).
12Transition moment variation with r from observed vibrational intensity distribution and calculated Franck-Condon factors Haugh, Schneider, et al., 1974.
13Av = -2652.80 + 2.81(v+1/2).
14Value for the heavier isotope (81Br).
15Lambda-type doubling constants (p ~ 2.05) in Barrow and Caunt, 1953, Lebreton, 1973.
16From D00(HBr+).


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

Marsigny, Lebreton, et al., 1968
Marsigny, L.; Lebreton, J.; Ferran, J.; Lagrange, R., Observation et earacterisation d'une nouvelle bande de la molecule HBr+(2«SIGMA»+ --> 2«PI»i). Structure fine de la bande (0-2) de cette transition, C.R. Acad. Sci. Paris, Ser. C, 1968, 266, 1731. [all data]

Lebreton, 1973
Lebreton, J., Transition A2«SIGMA»+ - X2«PI»i. Des ions moleculaires HBr+ et DBr+, J. Chim. Phys. Phys.-Chim. Biol., 1973, 70, 1188. [all data]

Haugh and Bayes, 1971
Haugh, M.J.; Bayes, K.D., Predissociation and dissociation energy of HBr+, J. Phys. Chem., 1971, 75, 1472. [all data]

Delwiche, Natalis, et al., 1973
Delwiche, J.; Natalis, P.; Momigny, J.; Collin, J.E., On the photoelectron spectra of the HBr and DBr, J. Electron Spectrosc. Relat. Phenom., 1973, 1, 219-225. [all data]

Barrow and Caunt, 1953
Barrow, R.F.; Caunt, A.D., The 2«SIGMA»+-2«PI»i band system of HBr+, Proc. Phys. Soc. London Sect. A, 1953, 66, 617. [all data]

Haugh, Schneider, et al., 1974
Haugh, M.J.; Schneider, B.S.; Smith, A.L., Transition moment variation in the A2«SIGMA»+ --> X2«PI»i transition of HCl+, DCl+ and HBr+, J. Mol. Spectrosc., 1974, 51, 123. [all data]


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