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 July, 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 40Ca2
A band system in the region 16100 - 16900 cm-1 and assigned to Ca2 by Kovalenok and Sokolov, 1967 is in all probability the same as that usually ascribed to CaO. 1
Emission continuum from 19500 to 25000 cm-1.
Hamada, 1931
A 1Σu+ ≤18963.7 ≥136.66 2 Z 0.7166 3  ≥0.058247 2 0.0003104 4  4.59E-08 5  ≤3.8058 A ← X 6 V 18999.7 7 Z
Weniger, 1966; missing citation
X 1Σg+ 0 64.928 Z 1.0651 0.00259 0.046113 0.0007028 -7.35E-06 9.52E-08 8  4.2773  


1The Bv values quoted by Kovalenok and Sokolov, 1967 are of the same order as those for CaO.
2Vibrational numbering unknown.
3ωexe= -0.00374(v+1/2)3 - 0.000080(v+1/2)4.
4αv= -[2.15(v+1/2)2 + 0.097[v+1/2)3]E-6.
5He= 1.9kE-14.
6RKR curves and Franck-Condon factors Balfour and Whitlock, 1975.
7Energy of the lowest observed vibrational level relative to X 1Σg+ (v=0).
8Dv= +[0.0431(v+1/2)+0.00107(v+1/2)2]E-7; He = -1.4E-13 Balfour and Whitlock, 1975 and higher order constants Balfour and Whitlock, 1975.
9Extrapolation of the vibrational levels in X 1Σg+.


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

Kovalenok and Sokolov, 1967
Kovalenok, G.V.; Sokolov, V.A., Quantum vibration analysis of the orange band of Ca2, Izv. Sib. Otd. Akad. Nauk SSSR, Ser. Khim. Nauk, 1967, 4, 118. [all data]

Hamada, 1931
Hamada, H., III. On the molecular spectra of mercury, zinc, cadmium, magnesium, and thallium, Philos. Mag., 1931, 12, 50. [all data]

Weniger, 1966
Weniger, S., L'elargissement de la raie 4226,73 Å(432 λSo-4P1 1P1o) de ca i dans les spectres de laboratoire et dans les etoiles d M in Proceedings IAU Colloquim on Late-Type Stars, Trieste, M. Hack, ed(s)., 1966, 25-34. [all data]

Balfour and Whitlock, 1975
Balfour, W.J.; Whitlock, R.F., The visible absorption spectrum of diatomic calcium, Can. J. Phys., 1975, 53, 472. [all data]


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