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

Carbon anion

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 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 12C2-
a 4Sigmau+ (19448) (1074) 1 (25)  (1.135) 1 (0.0035)    (1.573)  
B 2Sigmau+ 18390.88 1968.73 Z 14.433 -0.324 1.87745 2 0.01776 -0.00037 0.00000684 3  1.22330 B lrarrow X 4 V 18483.98 Z
missing citation
A 2Piu 5           A larrow X 
Lineberger and Patterson, 1972
X 2Sigmag+ 0 1781.04 Z 11.585 -0.027 1.74685 0.0167  0.00000669  1.26821  


1Constants derived Bondybey and Brus, 1975 from the perturbations Herzberg and Lagerqvist, 1968 in B 2Sigmau+. Ab initio calculations by Barsuhn, 1974 and Thulstrup and Thulstrup, 1974 independently predict the existence of a 4Sigmau+ state slightly above B 2Sigmau+ with re and omegae values near those derived from the perturbations.
2Small perturbations by a 4Sigmau+.
3Dv= +[1.0(v+1/2) + 0.08(v+1.2)2]E-7.
4The spectrum was observed in flash discharges in CH4 Herzberg and Lagerqvist, 1968, behind reflected shock waves [fel ~ 0.017 Cathro and Mackie, 1973], and in rare gas matrices Milligan and Jacox, 1969, Frosch, 1971, Bondybey and Nibler, 1972, missing citation, Brus and Bondybey, 1975. Conclusive proof that it belongs to C2- was supplied by two-photon photodetachment spectroscopy Lineberger and Patterson, 1972. Franck-Condon factors Singh and Maheshwari, 1971.
5Fragments of absorption bands.
6From D00(C2) and the electron affinities of C2 and of C(=1.268 eV).
7Photodetachment threshold Feldman, 1970.


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.

Lineberger and Patterson, 1972
Lineberger, W.C.; Patterson, T.A., Two photon photodetachment spectroscopy: the C2--2«SIGMA» states, Chem. Phys. Lett., 1972, 13, 40. [all data]

Bondybey and Brus, 1975
Bondybey, V.E.; Brus, L.E., Photophysics of C2-(B2«SIGMA»u+) in rare gas lattices: vibrational relaxation through intermediate a4«SIGMA»u+ levels, J. Chem. Phys., 1975, 63, 2223. [all data]

Herzberg and Lagerqvist, 1968
Herzberg, G.; Lagerqvist, A., A new spectrum associated with diatomic carbon, Can. J. Phys., 1968, 46, 2363. [all data]

Barsuhn, 1974
Barsuhn, J., Nonempirical calculations on the electronic spectrum of the molecular ion C2-, J. Phys. B:, 1974, 7, 155. [all data]

Thulstrup and Thulstrup, 1974
Thulstrup, P.W.; Thulstrup, E.W., A theoretical investigation of the low-lying states of the C2- ion, Chem. Phys. Lett., 1974, 26, 144. [all data]

Cathro and Mackie, 1973
Cathro, W.S.; Mackie, J.C., Oscillator strength of the C2-B2«SIGMA» - X2«SIGMA» transition: a shock-tube determination, J. Chem. Soc. Faraday Trans. 2, 1973, 69, 237. [all data]

Milligan and Jacox, 1969
Milligan, D.E.; Jacox, M.E., Studies of the photoproduction of electrons in inert solid matrices. The electronic spectrum of the species C2-, J. Chem. Phys., 1969, 51, 1952. [all data]

Frosch, 1971
Frosch, R.P., C2 and C2- spectra produced by the X irradiation of acetylene in rare-gas matrices, J. Chem. Phys., 1971, 54, 2660. [all data]

Bondybey and Nibler, 1972
Bondybey, V.; Nibler, J.W., Laser excited fluorescence studies of matrix isolated C2-, J. Chem. Phys., 1972, 56, 4719. [all data]

Brus and Bondybey, 1975
Brus, L.E.; Bondybey, V.E., Molecular ions and electron transport in rare gas lattices: C2- formation mechanism and X2«SIGMA»g+ = B2«SIGMA»u+ spectroscopy, J. Chem. Phys., 1975, 63, 3123. [all data]

Singh and Maheshwari, 1971
Singh, I.D.; Maheshwari, R.C., Isotope/effect on Franck-Condon factors & r-centroids for the new (1«SIGMA»u+-1«SIGMA»g+) system of isotopic C2 molecule, Indian J. Pure Appl. Phys., 1971, 9, 296. [all data]

Feldman, 1970
Feldman, D., Photoablosung von Elektronen bei einigen Stabilen Negativen Ionen, Z. Naturfor., 1970, 25A, 621. [all data]


Go To: Top, Constants of diatomic molecules, References