Home Symbol which looks like a small house Up Solid circle with an upward pointer in it


Constants of diatomic molecules

Go To: Top, References, Notes

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 H81Br+
A 2Sigma+ 28421.0 1404.0 1 37.75 1  5.9702 2 3 0.2476  4.300E-4 4  1.6842 A rarrow X 5 R 27904.6 6 Z
Norling, 1935; Barrow and Caunt, 1953; Marsigny, Lebreton, et al., 1968; missing citation
X 2Pii 0 7 2441.52 8 Z 47.40 9  8.0721 10 0.2363  [3.48E-4]  1.4484  


1From isotope relations and the constants for DBr+ Lebreton, 1973. Barrow and Caunt, 1953 derive DeltaG(1/2) = 1328.7 from band origins.
2Spin splitting constant gamma(v=0)= 2.105; small variation with N.
3Only 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).
4missing note
5Transition moment variation with r from observed vibrational intensity distribution and calculated Franck-Condon factors Haugh, Schneider, et al., 1974.
6Referring in the lower state to the zero point of the Hill-Van Vleck formula.
7Av = -2652.80 + 2.81(v+1/2).
8missing note
9missing note
10Lambda-type doubling constants (p ~ 2.05) in Barrow and Caunt, 1953, Lebreton, 1973.
11From the predissociation in the A 2Sigma+ state Haugh and Bayes, 1971; see 3. D00(HBr) + I.P.(Br) - I.P.(HBr) = 3.902 eV.
12Value for the heavier isotope (81Br).
13From D00(HBr+).
14Spin splitting constant gamma(v=0) = 1.068.
15Only 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+.
16A0 = -2651.45, A1= -2649.54, ...
17Lambda-type doubling constants (p ~ 1.05) in Lebreton, 1973.


Go To: Top, Constants of diatomic molecules, Notes

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

Norling, 1935
Norling, F., Uber die bandenspektren der ionisierten halogenwasserstoffe. I. Bromwasserstoffbanden, Z. Phys., 1935, 95, 179. [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]

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]

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]


Go To: Top, Constants of diatomic molecules, References