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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 September, 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 35Cl2+
B (2Sigmag+) (34400) 1           
A2 (2Pi1/2u) (20000) 1 2   [0.1778] 3 2    [2.329] 3 A2 rarrow X2 R 22746.96 3 Z
missing citation
A1 (2Pi3/2u) (20000) 1 2   [0.1788] 3 2  [0.00000049]  [2.322] 3 A1 rarrow X1 R 22199.54 3 Z
missing citation
X2 2Pi1/2g 645 1 644.77 Z 2.988  0.2697 0.00167    1.8907  
X1 2Pi3/2g 0 645.61 Z 3.015 0.007 0.26950 0.00164  0.00000018  1.8915  


1From the photoelectron spectrum Cornford, Frost, et al., 1971, Potts and Price, 1971.
2Several higher vibrational levels have been observed and analyzed Huberman, 1966 but they do not form regular progressions. The vibrational constants quoted in Herzberg, 1945 from Elliott and Cameron, 1937 just as the later values of Haranath and Rao, 1958 must be considered as erroneous Huberman, 1966. The partial rotational analysis of Rao and Rao, 1958 agrees essentially with the more extensive one of Huberman, 1966.
3Lowest observed vibrational level, not necessarily v=0; see 2.
4From D00 (Cl2), I.P.(Cl2), and I.P.(Cl).


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

Cornford, Frost, et al., 1971
Cornford, A.B.; Frost, D.C.; McDowell, C.A.; Ragle, J.L.; Stenhouse, I.A., Photoelectron spectra of the halogens, J. Chem. Phys., 1971, 54, 2651. [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]

Huberman, 1966
Huberman, F.P., The emission spectrum of Cl2+, J. Mol. Spectrosc., 1966, 20, 29. [all data]

Herzberg, 1945
Herzberg, G., Molecular spectra and molecular structure. II. Infrared and Raman spectra of polyatomic molecules, Pub. D. Van Nostrand Company, Inc., Princeton, New Jersey, 1945, 0. [all data]

Elliott and Cameron, 1937
Elliott, A.; Cameron, W.H.B., The emission band spectrum of chlorine-I, Proc. R. Soc. London A, 1937, 158, 681. [all data]

Haranath and Rao, 1958
Haranath, P.B.V.; Rao, P.T., The emission spectrum of chlorine (Cl2+), Indian J. Phys., 1958, 32, 401. [all data]

Rao and Rao, 1958
Rao, V.V.; Rao, P.T., The visible emission spectrum of Cl2+, Can. J. Phys., 1958, 36, 1557. [all data]


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