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 May, 1977

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 (208)Pb2
Emission bands in the region 12500 - 11100 cm-1, observed in Ar and Ne matrices by excitation with argon/krypton ion laser lines.
Teichman and Nixon, 1976
Absorption bands in the region 33400 - 34600 cm-1 (preceded by continuous fluctuations from 31300 to 33300 cm-1), 36800 - 38000, and 41000 - 42200 cm-1.
Weniger, 1967
B 19490.3 161.64 1 H 1.036 0.0055       B ↔ X 2 R 19515.7 H
missing citation; missing citation; Johnson, Cannell, et al., 1972
A 14465.6 162.4 1 0.4        A ↔ X 3 (R) 14491.5
missing citation; Johnson, Cannell, et al., 1972; Puri and Mohan, 1975
X 0 110.5 1 4 H 0.35         


1Constants obtained by Johnson, Cannell, et al., 1972 from a reclassification of bands in the blue-green and in the red system. The new analysis of the ground state seems to be confirmed by the observation of a lower state frequency of 111 cm-1 in laser-excited matrix emission spectra [see Teichman and Nixon, 1976 who attribute the 111 cm-1 interval to a matrix-induced splitting of the ground state]. The revised lower state constants imply, however, a strong contradiction to the usual rule that if ω' > ω" then B' > B" since according to the published spectrograms of Weniger, 1967 the B-X bands are strongly shaded to the red, i.e. B' < B".
2Previously called A-X. Also observed in inert gas matrices Brewer and Chang, 1972, Teichman and Nixon, 1976.
3Previously believed to have B as its lower state.
4 Johnson, Cannell, et al., 1972 give 119.1 which seems to be a typographical or arithmetical error since it does not represent the band head measurements of Shawhan, 1935.
5Thermochemical value (mass-spectrom.) Gingerich, Cocke, et al., 1976.


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

Teichman and Nixon, 1976
Teichman, R.A., III; Nixon, E.R., Absorption and laser-excited emission spectra of matrix-isolated Pb2, J. Mol. Spectrosc., 1976, 59, 299. [all data]

Weniger, 1967
Weniger, S., Etude du spectre d'absorption de la molecule de plomb, J. Phys. (Paris), 1967, 28, 595. [all data]

Johnson, Cannell, et al., 1972
Johnson, S.E.; Cannell, D.; Lunacek, J.; Broida, H.P., New molecular constants for the ground electronic state of Pb2, J. Chem. Phys., 1972, 56, 5723. [all data]

Puri and Mohan, 1975
Puri, S.N.; Mohan, H., Thermal emission spectrum (intercombinational system) of Pb2, Indian J. Pure Appl. Phys., 1975, 13, 206-207. [all data]

Brewer and Chang, 1972
Brewer, L.; Chang, C.-A., Matrix isolation of Pb and Pb2, J. Chem. Phys., 1972, 56, 1728. [all data]

Shawhan, 1935
Shawhan, E.N., Band spectrum of Pb2 in absorption and emission, Phys. Rev., 1935, 48, 343. [all data]

Gingerich, Cocke, et al., 1976
Gingerich, K.A.; Cocke, D.L.; Miller, F., Thermodynamic investigation of the lead molecules Pb2, Pb3, and Pb4 by mass spectrometry, J. Chem. Phys., 1976, 64, 4027. [all data]


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