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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 October, 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 12C16O+
K' 2Sigma+ [528.69 eV] 1           528.56 ev
Smith and Thomas, 1976
K 2Sigma+ [282.34 eV] 2           282.21 ev
Gelius, 1974; Smith and Thomas, 1976
H 2Sigma+ (~25eV) 3           
F (2Sigma) (105690) (1780) 4 (30)         (105470) 4
Asbrink, Fridh, et al., 1974
E (2Sigma) (87140) (1420) 4          86750 4
Asbrink, Fridh, et al., 1974
G (2Sigma) (73190) (1400) 4          72970 4
Asbrink, Fridh, et al., 1974
D (2Pi) (65230) (1350) 4          (64800) 4
Asbrink, Fridh, et al., 1974
C (2Deltar) 63012 5 1144 6 (Z) 33.3  1.357 6 0.024    1.346 C rarrow A R 42168.5 6 H
Marchand, d'Incan, et al., 1969
           C rarrow A R 41950.9 6 H
Marchand, d'Incan, et al., 1969
B 2Sigma+ 45876.7 1734.18 Z 27.927 0.3283 1.7992 7 8 0.03025  7.75E-06 2.2E-07 1.16877 B rarrow A 9 10 11 V 25226.0
Bulthuis, 1934; Rao and Sarma, 1953; missing citation
           B lrarrow X 9 10 11 12 R 45633.52 Z
missing citation; Herzberg, 1968
A 2Pii 20733.3 13 1562.06 14 Z 13.532 0.0131 1.58940 8 0.01942  0.0000066  1.24377 A rarrow X 15 10 11 R 20407.6 16 Z
missing citation; missing citation
X 2Sigma+ 0 2214.24 Z 15.164 -0.0007 1.97720 17 8 0.01896  6.35E-06  1.11514 18  
Dixon and Woods, 1975


1Upper state of oxygen K radiation in CO (See note b of CO).
2Upper state of carbon K radiation in CO (See note b of CO). 21
3This highly excited state Siegbahn, Nordling, et al., 1969 Thomas, 1970 is probably unstable and dissociating into C+ + O(3s) as suggested by the photoelectron and photoion spectra of Gardner and Samson, 1975.
4Fairly long progressions in the photoelectron spectrum; vibrational numbering uncertain. Predissociation into C+ +O Locht and Durer, 1975.
5A ~ +100.
6Vibrational numbering uncertain; rotational structure not fully resolved.
7Spin-splitting constant gamma ~ + 0.018.
8RKR potential functions Krupenie and Weissman, 1965, missing citation, Singh and Rai, 1966.
9Lifetime tau(v=0) = 55 ± 4 ns Hesser, 1968, Fowler, Skwerski, et al., 1969, Dotchin and Chupp, 1973, Jorgensen and Sorensen, 1975, slight increase with v Hesser, 1968, Dotchin and Chupp, 1973. Electronic branching ratio 1/tau A(B rarrow A) =0.08/tau(B) Judge and Lee, 1972, 1/tau A(B rarrow X) = 0.92/tau(B) Judge and Lee, 1972; f00(B-A) ~ 0.00071, f00(B-X) ~ 0.0065.
10Fluorescence by photoexcitation from the ground state X 1Sigma+ of CO Judge and Lee, 1972, Lee, Carlson, et al., 1974.
11Franck-Condon factors Nicholls, 1962, missing citation, missing citation, Krupenie and Benesch, 1968, Comes and Speier, 1971. Independence of electronic transition moment on r Judge and Lee, 1972, Maier and Holland, 1972; see, however, Robinson and Nicholls, 1960, Joshi, Sastri, et al., 1966, Jain, 1972.
12Isotopic bands Shvangiradze, Oganezov, et al., 1960, Pesic, Janjic, et al., 1974.
13A = -117.~5.
14Vibrational numbering confirmed by isotope studies Asundi, Dhumwad, et al., 1970.
15Lifetimes tau(v=1) = 3.49 mus Holland and Maier, 1972, tau(v=3) = 2.78 mus Holland and Maier, 1972, tau(v=4) = 2.63 mus Holland and Maier, 1972, tau(v=6) = 2.41 mus Holland and Maier, 1972. Anderson, Sutherland, et al., 1972 give values that are 10 to 50% higher; earlier values Bennett and Dalby, 1960, Fink and Welge, 1968 are 20% lower. sigma Refers to zero point of Hill - Van Vleck formula.
16missing note
17From the microwave spectrum B0 = 1.967465, spin-splitting constant gamma0 = +0.009105.
18Microwave sp.
19D00(CO) + I.P.(C)-I.P.(CO).
20From the electron impact appearance potential of CO++ in CO Dorman and Morrison, 1961, Newton and Sciamanna, 1970, reduced by 0.9 eV following Hurley, 1971; see also 23.
21Several higher lying states corresponding to excitation of a second electron have been observed by Gelius, 1974 ("1s shake-up spectrum").
22Rough estimate based on appearance potentials of CO++ from CO Dorman and Morrison, 1961, Newton and Sciamanna, 1970, and taking into account tentative assignments of the carbon and oxygen Auger spectra of CO Siegbahn, Nordling, et al., 1969, Hurley, 1971.
23The potential minimum of the ground state of CO++ lies about 4.7 eV above the dissociation limit C+(2P1/2) + O+(4S) (which lies 35.970 eV above the ground state of CO and is separated by a maximum of ~1.5 eV from this limit Newton and Sciamanna, 1970, Hurley, 1971.
24Derived by Hurley, 1971 from the carbon Auger spectrum of CO Siegbahn, Nordling, et al., 1969. At least six vibrational levels are observed.


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

Smith and Thomas, 1976
Smith, S.R.; Thomas, T.D., Core ionization potentials in carbon monoxide, J. Electron Spectrosc. Relat. Phenom., 1976, 8, 45. [all data]

Gelius, 1974
Gelius, U., Recent progress in ESCA studies of gases, J. Electron Spectrosc. Relat. Phenom., 1974, 5, 985. [all data]

Asbrink, Fridh, et al., 1974
Asbrink, L.; Fridh, C.; Lindholm, E.; Codling, K., Photoelectron spectrum and Rydberg transitions of CO, Phys. Scr., 1974, 10, 183. [all data]

Marchand, d'Incan, et al., 1969
Marchand, J.; d'Incan, J.; Janin, J., Etude d'une nouvelle transition electronique attribuee a l'ion CO+, Spectrochim. Acta, 1969, 25, 605. [all data]

Bulthuis, 1934
Bulthuis, H., The bandspectrum of CO+, Physica (The Hague), 1934, 1, 873. [all data]

Rao and Sarma, 1953
Rao, K.N.; Sarma, K.S., Band spectrum of CO+. The Baldet-Johnson system (B2«SIGMA» - A2«PI»), Mem. Soc. R. Sci. Liege Collect., 1953, 13, 4, 181-186. [all data]

Herzberg, 1968
Herzberg, G., Absorption spectra of molecular ions, Comment. Pontif. Acad. Sci., 1968, 2, 15, 1-8. [all data]

Dixon and Woods, 1975
Dixon, T.A.; Woods, R.C., Microwave absorption spectrum of the CO+ ion, Phys. Rev. Lett., 1975, 34, 61. [all data]

Siegbahn, Nordling, et al., 1969
Siegbahn, K.; Nordling, C.; Johansson, G.; Hedman, J.; Heden, P.F.; Hamrin, k.; Gelius, U.; Bergmark, T.; Werme, L.O.; Manne, R.; Baer, ESCA Applied to Free Molecules, North-Holland Publishing Company, Amsterdam, 1969, 0. [all data]

Thomas, 1970
Thomas, T.D., X-ray photoelectron spectroscopy of carbon monoxide, J. Chem. Phys., 1970, 53, 1744. [all data]

Gardner and Samson, 1975
Gardner, J.L.; Samson, J.A.R., Photion and photelectron spectroscopy of CO and N2, J. Chem. Phys., 1975, 62, 1447. [all data]

Locht and Durer, 1975
Locht, R.; Durer, J.M., New predissociations of CO and CO+ induced by low energy electron impact, Chem. Phys. Lett., 1975, 34, 508. [all data]

Krupenie and Weissman, 1965
Krupenie, P.H.; Weissman, S., Potential-energy curves for CO and CO+, J. Chem. Phys., 1965, 43, 1529. [all data]

Singh and Rai, 1966
Singh, R.B.; Rai, D.K., Potential-energy curves for O2+, N2+, and CO+, J. Mol. Spectrosc., 1966, 19, 424. [all data]

Hesser, 1968
Hesser, J.E., Absolute Transition Probabilities in Ultraviolet Molecular Spectra, J. Chem. Phys., 1968, 48, 6, 2518, https://doi.org/10.1063/1.1669477 . [all data]

Fowler, Skwerski, et al., 1969
Fowler, R.G.; Skwerski, P.R.; Anderson, R.A.; Copeland, G.E.; Holzberlein, T.M., Radiative lifetime of the B2«SIGMA»+ state of CO+, J. Chem. Phys., 1969, 50, 4133. [all data]

Dotchin and Chupp, 1973
Dotchin, L.W.; Chupp, E.L., Radiative lifetimes and pressure dependence of the relaxation rates of some vibronic levels in N2+, N2, CO+, and CO, J. Chem. Phys., 1973, 59, 3960. [all data]

Jorgensen and Sorensen, 1975
Jorgensen, S.W.; Sorensen, G., Radiative lifetimes in molecules studied by means of fast, molecular ion beams, J. Chem. Phys., 1975, 62, 2550. [all data]

Judge and Lee, 1972
Judge, D.L.; Lee, L.C., Electronic transition moments for the A --> X, B --> X, and B --> A transitions in CO+ and the A <-- B and B <-- X moments for the CO --> CO+ systems; absolute cross sections for the absorption processes, J. Chem. Phys., 1972, 57, 455. [all data]

Lee, Carlson, et al., 1974
Lee, L.C.; Carlson, R.W.; Judge, D.L.; Ogawa, M., Cross sections for production of the CO+(B2«SIGMA»+ --> X2«SIGMA»+) fluorescence by photoionization of CO, J. Geophys. Res., 1974, 79, 5286. [all data]

Nicholls, 1962
Nicholls, R.W., Franck-Condon factors and r-centroids to high vibrational quantum numbers for three band systems of CO+ and absolute band strengths for the comet-tail system, Can. J. Phys., 1962, 40, 1772. [all data]

Krupenie and Benesch, 1968
Krupenie, P.H.; Benesch, W., Electronic transition moment integrals for first ionization of CO and the A-X transition in Co+. Some limitations on the use of the r-centroid approximation, J. Res. Nat. Bur. Stand. Sect. A, 1968, 72, 495. [all data]

Comes and Speier, 1971
Comes, F.J.; Speier, F., Luminescence of diatomic molecular ions. I. Franck-Condon-factors and collisional deactivation, Z. Naturforsch. A, 1971, 26, 1998. [all data]

Maier and Holland, 1972
Maier, B., II; Holland, R.F., Electronic transition moment for the comet tail system of CO+, J. Phys. B:, 1972, 5, 118. [all data]

Robinson and Nicholls, 1960
Robinson, D.; Nicholls, R.W., Intensity measurements on the CO+ comet tail, and the BO «alpha» and «beta» molecular band systems, Proc. Phys. Soc. London, 1960, 75, 817. [all data]

Joshi, Sastri, et al., 1966
Joshi, K.C.; Sastri, V.D.P.; Parthasarathi, S., Absolute transition probabilities, oscillator strengths, and electronic transition moments for the first negative system of CO+, J. Quant. Spectrosc. Radiat. Transfer, 1966, 6, 215. [all data]

Jain, 1972
Jain, D.C., Einstein A coefficients, band oscillator strengths and absolute band strengths for the comet-tail band system of CO+, J. Phys. B:, 1972, 5, 199. [all data]

Shvangiradze, Oganezov, et al., 1960
Shvangiradze, R.R.; Oganezov, K.A.; Chikhladze, B.Ya., Isotopic band shifts in the electronic-vibrational spectra of some diatomic molecules, Opt. Spectrosc. Engl. Transl., 1960, 8, 239. [all data]

Pesic, Janjic, et al., 1974
Pesic, D.; Janjic, J.; Markovic, D.; Rytel, M.; Sewiec, T., Isotope shifts in the first negative system of CO+, Bull. Soc. Chim. Beograd., 1974, 39, 249. [all data]

Asundi, Dhumwad, et al., 1970
Asundi, R.K.; Dhumwad, R.K.; Patwardhan, A.B., Isotope shift studies of Herzberg bands of CO and comet-tail and Baldet-Johnson bands of CO+, J. Mol. Spectrosc., 1970, 34, 528. [all data]

Holland and Maier, 1972
Holland, R.F.; Maier, W.B., II, Study of the A --> X transitions in N2+ and CO+, J. Chem. Phys., 1972, 56, 5229. [all data]

Anderson, Sutherland, et al., 1972
Anderson, R.; Sutherland, R.; Frey, N., Radiative lifetimes of the A2«PI» state of CO+, J. Opt. Soc. Am., 1972, 62, 1127. [all data]

Bennett and Dalby, 1960
Bennett, R.G.; Dalby, E.W., Experimental oscillator strength of the comet-tail system of CO+, J. Chem. Phys., 1960, 32, 1111. [all data]

Fink and Welge, 1968
Fink, E.H.; Welge, K.H., Lebensdauern und Loschquerschnitte elektronisch angeregter Zustande von N2O+, NO, O2+, CO+ und CO, Z. Naturforsch. A, 1968, 23, 358. [all data]

Dorman and Morrison, 1961
Dorman, F.H.; Morrison, J.D., Double and triple ionization in molecules induced by electron impact, J. Chem. Phys., 1961, 35, 575. [all data]

Newton and Sciamanna, 1970
Newton, A.S.; Sciamanna, A.F., Metastable dissociation of the doubly charged carbon monoxide ion, J. Chem. Phys., 1970, 53, 132. [all data]

Hurley, 1971
Hurley, A.C., Auger spectra of CO and long-lived states of CO++, J. Chem. Phys., 1971, 54, 3656. [all data]


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