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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 November, 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 4He2+
A 2Sigmag+Repulsive state arising from He(11S) + He+(12S). 1
Browne, 1966; Olson and Mueller, 1967; Gupta and Matsen, 1967
X 2Sigmag+ 0 1698.5 2 35.3  7.211 2 0.224  5.1E-4  1.0808  
Ginter and Ginter, 1968; Ginter and Battino, 1970; Ginter and Brown, 1972


1The potential functions of several excited states have been calculated by Browne, 1966, Bardsley, 1971. A 2Sigmag+, the lowest 2Sigmag+ state, has a very small van der Waals minimum at 5.3 Å and a hump near 0.8 Å caused by an avoided crossing with the second lowest 2Sigmag+ state; see Gupta and Matsen, 1967. The states 4Sigmau+, 2Sigmag+, 2Sigmau+ arising from He(2 3S) + He+(1 2S) are found to have minima with De(4Sigmau+) ~1.1 eV, De(2Sigmag+) ~0.57 eV, De(2Sigmau+) ~ 0.46 eV, respectively; several other states are purely repulsive.
2Constants obtained by extrapolation from the nppi 3Pig Rydberg series of He2; they agree with values derived from the theoretical potential function of Browne, 1966 and Gupta and Matsen, 1967.
3From the theoretical De= 2.469 ± -0.006 eV Liu, 1971. From He - He+ differential scattering cross sections Olson and Mueller, 1967 and Weise, Mittmann, et al., 1971 obtain De= 2.34 eV Olson and Mueller, 1967 and De= 2.55 eV Weise, Mittmann, et al., 1971, respectively.
4Theoretical value Fraga and Ransil, 1962.
5The theoretical potential function according to Fraga and Ransil, 1962, Conroy and Bruner, 1967 shows a local minimum at 0.704 Å and 69600 cm-1 above He+ + He+, separated from this limit by a maximum at 1.151 Å and 82200 cm-1. He2++ has not yet been found mass- spectrometrically, nor has its spectrum been observed.


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.

Browne, 1966
Browne, J.C., Wavefunctions and potential curves for excited states of He2+, J. Chem. Phys., 1966, 45, 2707-2709. [all data]

Olson and Mueller, 1967
Olson, R.E.; Mueller, C.R., Inversion of low-energy experimental He-He+ elastic differential scattering sections to the 2«SIGMA»g+ and 2«SIGMA»u+ potentials, J. Chem. Phys., 1967, 46, 10, 3810-3817. [all data]

Gupta and Matsen, 1967
Gupta, B.K.; Matsen, F.A., Potential curves for the X2«SIGMA»2+ and the lowest 2«SIGMA»g+ states of the helium molecule ion, J. Chem. Phys., 1967, 47, 4860-4863. [all data]

Ginter and Ginter, 1968
Ginter, M.L.; Ginter, D.S., Spectrum and structure of the He2 molecule. V. Characterization of the triplet states associated with the UAO's 6-17p«pi» and 7-12p«sigma», J. Chem. Phys., 1968, 48, 2284. [all data]

Ginter and Battino, 1970
Ginter, M.L.; Battino, R., Potential-energy curves for the He2 molecule, J. Chem. Phys., 1970, 52, 4469. [all data]

Ginter and Brown, 1972
Ginter, M.L.; Brown, C.M., Dissociation energies of X2«SIGMA»u+ (HE2+) and A1«SIGMA»u+ (He2), J. Chem. Phys., 1972, 56, 672. [all data]

Bardsley, 1971
Bardsley, J.N., Potential Curves for He2+ and Li2+, Phys. Rev. A: Gen. Phys., 1971, 3, 4, 1317-1321. [all data]

Liu, 1971
Liu, B., Dissociation energies of He2+(X2«SIGMA»u+) and He2(A1«SIGMA»u+), Phys. Rev. Lett., 1971, 27, 1251. [all data]

Weise, Mittmann, et al., 1971
Weise, H.-P.; Mittmann, H.-U.; Ding, A.; Henglein, A., Streuung von Ionen. II. Regenbogeneffekt bei der elastichen Streuung von Protonen an Helium, Neon, Krypton, Xenon und von He+ an Helium, Z. Naturforsch. A, 1971, 26, 1122. [all data]

Fraga and Ransil, 1962
Fraga, S.; Ransil, B.J., Studies in molecular structure. VIII. He2++ in the single- and many-configuration LCAO MO SCF approximation, J. Chem. Phys., 1962, 37, 5, 1112-1119. [all data]

Conroy and Bruner, 1967
Conroy, H.; Bruner, B.L., Molecular Schrodinger equation. VI. Results for H3 and other simple systems, J. Chem. Phys., 1967, 47, 3, 921-930. [all data]


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