Dicarbon

Gas phase thermochemistry data

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

Quantity Value Units Method Reference Comment
ΔfH°gas837.74kJ/molReviewChase, 1998Data last reviewed in December, 1969
Quantity Value Units Method Reference Comment
S°gas,1 bar199.39J/mol*KReviewChase, 1998Data last reviewed in December, 1969

Gas Phase Heat Capacity (Shomate Equation)

Cp° = A + B*t + C*t2 + D*t3 + E/t2
H° − H°298.15= A*t + B*t2/2 + C*t3/3 + D*t4/4 − E/t + F − H
S° = A*ln(t) + B*t + C*t2/2 + D*t3/3 − E/(2*t2) + G
    Cp = heat capacity (J/mol*K)
    H° = standard enthalpy (kJ/mol)
    S° = standard entropy (J/mol*K)
    t = temperature (K) / 1000.

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Temperature (K) 298. to 700.700. to 6000.
A 123.909230.50408
B -348.00675.445811
C 485.0971-0.853373
D -232.79940.065641
E -1.2402980.814750
F 808.2777831.5784
G 426.6132240.4039
H 837.7372837.7372
ReferenceChase, 1998Chase, 1998
Comment Data last reviewed in December, 1969 Data last reviewed in December, 1969

Constants of diatomic molecules

Go To: Top, Gas phase thermochemistry data, 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
SymbolMeaning
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
StateTeωeωexeωeyeBeαeγeDeβereTrans.ν00
Theoretical work and potential functions Read and Vanerslice, 1962 Fougere and Nesbet, 1966 Verhaegen, Richards, et al., 1967 Verhaegen, 1968.
F 1Πu [75456.9] [1557.5] Z   1.645 0.019  0.000006  1.307 F ← X R 74532.9 Z
↳missing citation
g 3Δg [73183.6] 1 [1458.06] Z   1.5238 0.170  0.0000066  1.3579 g ← a R 71649.6 Z
↳missing citation
f 3Σg- 71045.8 1360.5 Z 14.8  1.448 2 0.04 3 0.006 0.000010  1.393 f ← a R 70188.4 Z
↳missing citation
StateTeωeωexeωeyeBeαeγeDeβereTrans.ν00
E 1Σg+ 55034.7 1671.50 Z 40.02 0.248 1.7897 0.0387 4 -0.00055 0.0000083 0.0000006 1.2529 E → A 5 V 46668.3 Z
↳missing citation
d 1Σu+ 43239.44 1829.57 Z 13.94  1.8332 6 0.0196  0.00000732 6  1.238 D ↔ X 7 43226.74 6 Z
↳missing citation; Norrish, Porter, et al., 1952; Messerle, 1968
e 3Πg 40796.65 8 1106.56 Z 39.26 2.805 9 1.1922 0.0242  0.0000063 0.00000029 1.5351 e → a 10 R 39806.46 Z
↳missing citation
C' 1ΠgPreliminary constants from perturbations in C 1Πg; see Messerle and Krauss, 1967.
StateTeωeωexeωeyeBeαeγeDeβereTrans.ν00
C 1Πg 34261.3 1809.1 Z 15.81 11  1.7834 0.018 11  0.0000068  1.2552 C → A 12 VR 25969.19 Z
↳Dieke and Lochte-Holtgreven, 1930; Herzberg and Sutton, 1940; Herzberg, 1945; Cisak, Dabrowska, et al., 1969
d 3Πg 20022.50 13 1788.22 Z 16.440 -0.5067 14 1.7527 15 0.01608 -0.001274 0.00000674 0.000000103 1.2661 d ↔ a 16 VR 19378.44 Z
↳missing citation; Bugrim, Lyutyi, et al., 1965; missing citation; Phillips and Davis, 1968
           (d ← X) 17 
c 3Σu+ 13312.1 1961.6 18 13.7  1.87 18     1.23  
A 1Πu 8391.00 1608.35 Z 12.078 -0.0119 1.6134 20 0.01686 19 -0.000054 0.00000644 19 0.000000036 1.31843 A ↔ X 21 R 8268.16 Z
↳Ballik and Ramsay, 1963
StateTeωeωexeωeyeBeαeγeDeβereTrans.ν00
b 3Σg- 6434.27 1470.45 Z 11.19 0.028 22 1.49852 23 0.01634 -0.000087 24 0.00000622  1.36928 b → a 25 R 5632.7 Z
↳missing citation
a 3Πu 716.24 26 1641.35 Z 11.67  1.63246 27 0.01661  0.00000644  1.31190  
X 1Σg+ 0 1854.71 Z 13.340 28 -0.172 28 1.81984 0.01765 28 -0.00023 0.00000692 28 0.000000081 1.24253  

Notes

1A0= -8.8+0.020J; A1= -7.4.
2Spin splitting constant λ ~0.41.
3missing note
4Rotational constants reevaluated; Freymark, 1951 gives Be = 1.7930, αe = 0.0421.
5Franck-Condon factors Halmann and Laulicht, 1966; electronic transition moment Cooper and Nicholls, 1975.
6From Messerle, 1968; slightly different constants in Landsverk, 1939. βe~3E-8.
7Radiative lifetime τ=l4.6 ns Smith, 1969, f00= 0.055 Smith, 1969. The corresponding electronic transition moment is in only moderate agreement with Cooper and Nicholls, 1975. Franck-Condon factors Nicholls, Fraser, et al., 1959, Halmann and Laulicht, 1966.
8A not determined, but much smaller than for a 3Πu.
9ωeze= -0.1271.
10Franck-Condon factors Nicholls, Fraser, et al., 1959, Jain, 1964, Halmann and Laulicht, 1966: el. trans. moment Cooper and Nicholls, 1975.
11The ΔG and Bv curves are irregular Phillips, 1950, Messerle and Krauss, 1967, 2 and cannot be represented by the constants given without the use of higher order terms. The perturbation is strongest near v=5. Breaking-off at high J observed Messerle and Krauss, 1967 in v=0, 1, 2.
12Franck-Condon factors Nicholls, Fraser, et al., 1959, Halmann and Laulicht, 1966; el. trans. moment Cooper and Nicholls, 1975.
13A= -16.9.
14 Kini and Savadatti, 1969 have observed bands up to v'=14
15Numerous small perturbations by higher levels of b 3Σg- Callomon and Gilby, 1963 and X 1Σg+ Phillips, 1968 and by unidentified states. Swan bands emitted in low-pressure oxy-acetylene flames show a distinct intensity alternation ascribed to excitation by collisions with c 3Σu+ carbon molecules Bleekrode and Nieuwpoort, 1965, Bleekrode, 1967. Under certain conditions in discharges through CO the v'=6 progression of the Swan system appears almost exclusively and was at one time considered as a separate band system, the so-called high-pressure bands of carbon Herzberg, 1946, Kunz, Harteck, et al., 1967, Meinel and Messerle, 1968*. Isotope studies Dhumwad and Narasimham, 1968 leave no doubt that the high-pressure bands are the v'=6 progression of the Swan system.
16Radiative lifetime τ = 170 ns Smith, 1969, in reasonable agreement with Fink and Welge, 1967 but much shorter than Jeunehomme and Schwenker, 1965. f values obtained from the lifetime measurements as well as by other methods Fairbairn, 1966, Harrington, Modica, et al., 1966, Sviridov, Sobolev, et al., 1966, Arnold, 1968 have been reviewed in Danylewych and Nicholls, 1974. The latter authors' expression for the r dependence of the electronic transition moment was placed on an absolute scale using an average f00 = 0.020. For a more recent measurement of the electronic transition moment see Cooper and Nicholls, 1975. Franck-Condon factors Nicholls, Fraser, et al., 1959, Jain, 1964, Ortenberg, 1964, Spindler, 1965, Halmann and Laulicht, 1966.
17In solid matrices; tentative assignment by Barger and Broida, 1965 who also report the observation of d←a. See, however, Weltner and McLeod, 1966.
18From perturbations in A 1Πu Ballik and Ramsay, 1963.
19Very slightly revised constants in Marenin and Johnson, 1970 based on the same data.
20Λ-type doubling, Δvef = -0.00023J(J+1). Perturbations by c 3Σu+.
21f00 = 0.0025; see Roux, Cerny, et al., 1976 for a comparison with other absolute measurements. Reasonably consistent with the electronic transition moment obtained by Cooper and Nicholls, 1975. Franck-Condon factors Nicholls, Fraser, et al., 1959, Ortenberg, 1964, Spindler, 1965, Halmann and Laulicht, 1966.
22 Callomon and Gilby, 1963
23Spin-splitting parameters λ0 = 0.11, γ0 = -0.00365 Veseth, 1975. Small perturbations by levels of X 1Σg+ Ballik and Ramsay, 1963, 2.
24 Callomon and Gilby, 1963.
25Franck-Condon factors Halmann and Laulicht, 1966; electronic transition moment Cooper and Nicholls, 1975.
26A = -15.25; Veseth, 1975 gives additional spin-coupling constants.
27Λ-type doubling; see Ballik and Ramsay, 1963, 2 and Veseth, 1975.
28From Ballik and Ramsay, 1963, very slightly revised constants in Marenin and Johnson, 1970 based on the same data.
29Average of thermochemical values Brewer, Hicks, et al., 1962, Kordis and Gingerich, 1973. Smaller values of 6.07 and 6.11 eV have been derived on the basis of a somewhat doubtful extrapolation of the vibrational levels in d 3Πg Messerle and Krauss, 1967, 3 and of an extrapolated limiting curve of the C 1Πg state Messerle and Krauss, 1967. See also Drowart, Burns, et al., 1959.
30From photoionization and heat of formation of C2N2 Dibeler and Liston, 1967.

References

Go To: Top, Gas phase thermochemistry data, 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.

Chase, 1998
Chase, M.W., Jr., NIST-JANAF Themochemical Tables, Fourth Edition, J. Phys. Chem. Ref. Data, Monograph 9, 1998, 1-1951. [all data]

Read and Vanerslice, 1962
Read, S.M.; Vanerslice, J.T., Potential energy curves for C2, J. Chem. Phys., 1962, 36, 2366. [all data]

Fougere and Nesbet, 1966
Fougere, P.F.; Nesbet, R.K., Electronic structure of C2, J. Chem. Phys., 1966, 44, 285. [all data]

Verhaegen, Richards, et al., 1967
Verhaegen, G.; Richards, W.G.; Moser, C.M., Low-lying valence levels of BN and C2. The ground state of BN, J. Chem. Phys., 1967, 46, 160. [all data]

Verhaegen, 1968
Verhaegen, G., Theoretical calculation of the electronic states of C2+, J. Chem. Phys., 1968, 49, 4696. [all data]

Norrish, Porter, et al., 1952
Norrish, R.G.W.; Porter, G.; Thrush, B.A., Detection of diatomic radical absorption spectra during combustion, Nature (London), 1952, 169, 582. [all data]

Messerle, 1968
Messerle, G., Anregung hoher Rotationsniveaus von C2-Banden, Z. Naturforsch. A, 1968, 23, 470. [all data]

Messerle and Krauss, 1967
Messerle, G.; Krauss, L., Die Dissoziation des C2 - Molekuls durch Rotation, Z. Naturforsch. A, 1967, 22, 2023. [all data]

Dieke and Lochte-Holtgreven, 1930
Dieke, G.H.; Lochte-Holtgreven, W., Uber einige banden des kohlenstoffmolekuls, Z. Phys., 1930, 62, 767. [all data]

Herzberg and Sutton, 1940
Herzberg, G.; Sutton, R.B., Tail bands of the deslandres-d'azambuja system of the C2 molecule, Can. J. Res. Sect. A, 1940, 18, 74. [all data]

Herzberg, 1945
Herzberg, G., Molecular spectra and molecular structure. II. Infrared and Raman spectra of polyatomic molecules, Pub. D. Van Nostrand Company, Inc., Princeton, New Jersey, 1945, 0. [all data]

Cisak, Dabrowska, et al., 1969
Cisak, H.; Dabrowska, K.; Rytel, M., The Deslandres-d'Azambuja bands of isotopic C2 molecules, Acta Phys. Pol., 1969, 36, 497. [all data]

Bugrim, Lyutyi, et al., 1965
Bugrim, E.D.; Lyutyi, A.I.; Rossikhin, V.S.; Tsikora, I.L., New bands in the Swan system of the C2 molecule, Opt. Spectrosc. Engl. Transl., 1965, 19, 292, In original 524. [all data]

Phillips and Davis, 1968
Phillips, J.G.; Davis, S.P., Berkely analyses of molecular spectra, Pub. University of California Press, Berkeley and Los Angeles, 1968, 0. [all data]

Ballik and Ramsay, 1963
Ballik, E.A.; Ramsay, D.A., An extension of the Phillips system of C2 and a survey of C2 states, Astrophys. J., 1963, 137, 84. [all data]

Freymark, 1951
Freymark, H., Uber ein neues Bandensystem des C2-Molekuls im Ultravioletten, Ann. Phys. (Neue Folge), 1951, 8, 221. [all data]

Halmann and Laulicht, 1966
Halmann, M.; Laulicht, I., Isotope effects on vibrational transition probabilities. IV. Electronic transitions of isotopic C2, CO, CN, H2, and CH molecules, Astrophys. J. Suppl. Ser., 1966, 12, 307. [all data]

Cooper and Nicholls, 1975
Cooper, D.M.; Nicholls, R.W., Measurments of the electronic transition moments of C2-band systems, J. Quant. Spectrosc. Radiat. Transfer, 1975, 15, 139. [all data]

Landsverk, 1939
Landsverk, O.G., A 1Σ→1Σ transition of the C2 molecule, Phys. Rev., 1939, 56, 769-777. [all data]

Smith, 1969
Smith, W.H., Transition probabilities for the Swan and Mulliken C2 bands, Astrophys. J., 1969, 156, 791. [all data]

Nicholls, Fraser, et al., 1959
Nicholls, R.W.; Fraser, P.A.; Jarmain, W.R., Transition probability parameters of molecular spectra arising from combustion processes, Combust. Flame, 1959, 3, 13. [all data]

Jain, 1964
Jain, D.C., Transition probability parameters of the Swan and the Fox-Herzberg band systems of the C2 molecule, J. Quant. Spectrosc. Radiat. Transfer, 1964, 4, 427. [all data]

Phillips, 1950
Phillips, J.G., On the identification of the 3670 A band of the C2 molecule, Astrophys. J., 1950, 112, 131. [all data]

Messerle and Krauss, 1967, 2
Messerle, G.; Krauss, L., Ein neues c'1Πg - b1Πu - Bandensystem des C2 - Molekuls, Z. Naturforsch. A, 1967, 22, 2015. [all data]

Kini and Savadatti, 1969
Kini, K.S.; Savadatti, M.I., Extension of the C2(A3Πg-X'3Πu) band system, J. Phys. B:, 1969, 2, 307. [all data]

Callomon and Gilby, 1963
Callomon, J.H.; Gilby, A.C., New observations on the Swan bands of C2, Can. J. Phys., 1963, 41, 995. [all data]

Phillips, 1968
Phillips, J.G., Perturbations in the Swan system of the C2 molecule, J. Mol. Spectrosc., 1968, 28, 233. [all data]

Bleekrode and Nieuwpoort, 1965
Bleekrode, R.; Nieuwpoort, W.C., Absorption and emission measurements of C2 and CH electronic bands in low-pressure oxyacetylene flames, J. Chem. Phys., 1965, 43, 3680. [all data]

Bleekrode, 1967
Bleekrode, R., Absorption and emission spectroscopy of C2, CH and OH in low-pressure oxyacetylene flames, Philips Res. Rep. Suppl., 1967, 7, 1. [all data]

Herzberg, 1946
Herzberg, G., On the high pressure bands of carbon and the formation of C2 molecules, Phys. Rev., 1946, 70, 762. [all data]

Kunz, Harteck, et al., 1967
Kunz, C.; Harteck, P.; Dondes, S., Mechanism for excitation of the C2 high-pressure bands (C + C2O → C2(A3Π) + CO), J. Chem. Phys., 1967, 46, 4157. [all data]

Meinel and Messerle, 1968
Meinel, H.; Messerle, G., Investigation of the fine structure of the C2 high-pressure bands, Astrophys. J., 1968, 154, 381. [all data]

Dhumwad and Narasimham, 1968
Dhumwad, R.K.; Narasimham, N.A., Isotope shift studies of the high-pressure carbon bands, Can. J. Phys., 1968, 46, 1254. [all data]

Fink and Welge, 1967
Fink, E.H.; Welge, K.H., Lifetime measurements on CH(A2Δ), CH(B2Σ-), and C2(A3Πg) by the phase-shift method, J. Chem. Phys., 1967, 46, 4315. [all data]

Jeunehomme and Schwenker, 1965
Jeunehomme, M.; Schwenker, R.P., Focused laser-beam experiment and the oscillator strength of the Swan system, J. Chem. Phys., 1965, 42, 2406. [all data]

Fairbairn, 1966
Fairbairn, A.R., A shock-tube study of the oscillator strength of the C2 Swan bands, J. Quant. Spectrosc. Radiat. Transfer, 1966, 6, 325. [all data]

Harrington, Modica, et al., 1966
Harrington, J.A.; Modica, A.P.; Libby, D.R., Shock-tube determination of the C2(A3Π → X3Π) and CF(A2Σ+ → X2Π) band-system oscillator strengths, J. Chem. Phys., 1966, 44, 3380. [all data]

Sviridov, Sobolev, et al., 1966
Sviridov, A.G.; Sobolev, N.N.; Novgorodov, M.Z., Determination of the matrix elements of the dipole moments of the electronic transitions of the Swan band system of the C2 molecule. II. Absorption method, J. Quant. Spectrosc. Radiat. Transfer, 1966, 6, 337. [all data]

Arnold, 1968
Arnold, J.O., A shock tube determination of the electronic transition moment of the C2(Swan), bands, J. Quant. Spectrosc. Radiat. Transfer, 1968, 8, 1781. [all data]

Danylewych and Nicholls, 1974
Danylewych, L.L.; Nicholls, R.W., Intensity measurements on the C2 (d3Πg-a3Πu) Swan band system. I. Intercept and partial band methods, Proc. R. Soc. London A, 1974, 339, 197-212. [all data]

Ortenberg, 1964
Ortenberg, F.S., Calculation of Franck-Condon factors for the NO, C2, and CO band systems, Opt. Spectrosc. Engl. Transl., 1964, 16, 398, In original 729. [all data]

Spindler, 1965
Spindler, R.J., Franck-Condon factors based on RKR potentials with applications to radiative absorption coefficients, J. Quant. Spectrosc. Radiat. Transfer, 1965, 5, 165. [all data]

Barger and Broida, 1965
Barger, R.L.; Broida, H.P., Spectra of C2 in solidified gases at 4º and 20 ºK, J. Chem. Phys., 1965, 43, 7, 2371-2376. [all data]

Weltner and McLeod, 1966
Weltner, W., Jr.; McLeod, D., Jr., Spectroscopy of Carbon Vapor Condensed in Rare-Gas Matrices at 4°K. III, J. Chem. Phys., 1966, 45, 8, 3096, https://doi.org/10.1063/1.1728066 . [all data]

Marenin and Johnson, 1970
Marenin, I.R.; Johnson, H.R., New molecular constants for the Phillips system of C2, J. Quant. Spectrosc. Radiat. Transfer, 1970, 10, 305. [all data]

Roux, Cerny, et al., 1976
Roux, F.; Cerny, D.; d'Incan, J., Experimental oscillator strengths in the C2(A1Πu-X1Σg+) Phillips band system, Astrophys. J., 1976, 204, 940. [all data]

Veseth, 1975
Veseth, L., Molecular parameters for the a3Πu and b3Σg- states in C2, Can. J. Phys., 1975, 53, 299. [all data]

Ballik and Ramsay, 1963, 2
Ballik, E.A.; Ramsay, D.A., The A'3Σg--X'3Πu band system of the C2 molecule, Astrophys. J., 1963, 137, 61. [all data]

Brewer, Hicks, et al., 1962
Brewer, L.; Hicks, W.T.; Krikorian, O.H., Heat of sublimation and dissociation energy of gaseous C2, J. Chem. Phys., 1962, 36, 182. [all data]

Kordis and Gingerich, 1973
Kordis, J.; Gingerich, K.A., Gaseous phosphorus compounds. IX. Mass spectrometric studies of equilibria in the carbon-phosporus system, J. Chem. Phys., 1973, 58, 5058. [all data]

Messerle and Krauss, 1967, 3
Messerle, G.; Krauss, L., Spektroskopische Bestimmung der Dissoziationsenergie des C2-Molekuls aus den 3Πg - Termen, Z. Naturforsch. A, 1967, 22, 1744. [all data]

Drowart, Burns, et al., 1959
Drowart, J.; Burns, R.P.; DeMaria, G.; Inghram, M.G., Mass spectrometric study of carbon vapor, J. Chem. Phys., 1959, 31, 1131. [all data]

Dibeler and Liston, 1967
Dibeler, V.H.; Liston, S.K., Mass-spectrometric study of photoionization. VIII.Dicyanogen and the cyanogen halides, J. Chem. Phys., 1967, 47, 4548. [all data]

Notes

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