Ethynyl radical

Formula: C₂H
Molecular weight: 25.0293
IUPAC Standard InChI: InChI=1S/C2H/c1-2/h1H
IUPAC Standard InChIKey: XEHVFKKSDRMODV-UHFFFAOYSA-N
CAS Registry Number: 2122-48-7
Chemical structure:
This structure is also available as a 2d Mol file or as a computed 3d SD file
The 3d structure may be viewed using Java or Javascript.
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Other data available:
- Gas phase thermochemistry data
- Ion clustering data
Data at other public NIST sites:
- Microwave spectra (on physics lab web site)
- Gas Phase Kinetics Database
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Reaction thermochemistry data

Go To: Top, Gas phase ion energetics data, Vibrational and/or electronic energy levels, References, Notes

Data compiled by: John E. Bartmess

Note: Please consider using the reaction search for this species. This page allows searching of all reactions involving this species. A general reaction search form is also available. Future versions of this site may rely on reaction search pages in place of the enumerated reaction displays seen below.

Individual Reactions

(C₂H₂^- • 4294967295 Ethynyl radical ) + = C₂H₂^-

By formula: (C₂H₂^- • 4294967295C₂H) + C₂H = C₂H₂^-

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	78.5 ± 3.6	kcal/mol	N/A	Ervin, Gronert, et al., 1990	gas phase; Vinylidene neutral: ΔHf<=99±2 kcal, Kiefer, Sidhu, et al., 1989
Δ_rH°	44.6 ± 3.3	kcal/mol	Ther	Guo and Grabowski, 1990	gas phase; Between PhF, Me3P

Gas phase ion energetics data

Go To: Top, Reaction thermochemistry data, Vibrational and/or electronic energy levels, References, Notes

Data evaluated as indicated in comments:
HL - Edward P. Hunter and Sharon G. Lias
L - Sharon G. Lias

Data compiled as indicated in comments:
B - John E. Bartmess
LL - Sharon G. Lias and Joel F. Liebman
LLK - Sharon G. Lias, Rhoda D. Levin, and Sherif A. Kafafi

View reactions leading to C₂H⁺ (ion structure unspecified)

Quantity	Value	Units	Method	Reference	Comment
IE (evaluated)	11.61 ± 0.07	eV	N/A	N/A	L
Quantity	Value	Units	Method	Reference	Comment
Proton affinity (review)	180.	kcal/mol	N/A	Hunter and Lias, 1998	HL
Quantity	Value	Units	Method	Reference	Comment
Gas basicity	172.3	kcal/mol	N/A	Hunter and Lias, 1998	HL

Electron affinity determinations

EA (eV)	Method	Reference	Comment
2.9689 ± 0.0011	N/A	Zhou, Garand, et al., 2007	B
2.9690 ± 0.0060	LPES	Ervin and Lineberger, 1991	B
2.956 ± 0.020	LPES	Taylor, Xu, et al., 1998	B
2.94 ± 0.10	LPD	Janousek, Brauman, et al., 1979	Adiabatic EA: 3.18±0.25 eV; B
>2.30 ± 0.70	EIAE	Thynne and MacNiel, 1971	From C₂H₄; B
3.730 ± 0.050	PD	Feldman, 1970	B
2.10 ± 0.30	EIAE	Locht and Momigny, 1970	From C₂H₂, C₂H₄; B
>2.79998	EIAE	Trepka and Neuert, 1963	From C₂H₄; B
2.64955	SI	Page and Goode, 1969	The Magnetron method, lacking mass analysis, is not considered reliable.; B

Ionization energy determinations

IE (eV)	Method	Reference	Comment
11.61 ± 0.07	DER	Norwood and Ng, 1989	LL
11.7	DER	Lias, Bartmess, et al., 1988	LL
11.31 ± 0.13	DER	Ono and Ng, 1981	LLK
11.51	DER	Ono and Ng, 1981	Unpublished result of S.I.Miller and J.Berkowitz; LLK
11.96 ± 0.05	DER	Okabe and Dibeler, 1973	LLK
11.96 ± 0.05	DER	Dibeler, Walker, et al., 1973	LLK
11.6 ± 0.5	EI	Wyatt and Stafford, 1972	LLK

Anion protonation reactions

C₂H^- + =

By formula: C₂H^- + H⁺ = C₂H₂

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	379. ± 5.	kcal/mol	AVG	N/A	Average of 8 values; Individual data points
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	370. ± 5.	kcal/mol	AVG	N/A	Average of 7 values; Individual data points

Vibrational and/or electronic energy levels

Go To: Top, Reaction thermochemistry data, Gas phase ion energetics data, References, Notes

Data compiled by: Marilyn E. Jacox

State: 3ps Ryd

Energy (cm^-1)	Med.	References


T_o = 72100 ± 1300	gas	Cool and Goodwin, 1991

State: C

Energy (cm^-1)		Med.	λ_min (nm)	λ_max (nm)	References


T_o = 51387 ± 25	T	Ar	160	195	Chang and Graham, 1982

Approximate type of mode	cm^-1	Med.	Method	References


CC stretch	2175 ± 25	Ar	AB	Chang and Graham, 1982
Bend	630 ± 25	Ar	AB	Chang and Graham, 1982

State: B

Energy (cm^-1)		Med.	Transition	λ_min (nm)	λ_max (nm)	References


T_o = 39157.4	U	gas	B-X	235	313	Hsu, Wang, et al., 1992
						Hsu, Lin, et al., 1993
						Some, Remy, et al., 1995
						Hsu, Shiu, et al., 1995
						Chiang and Hsu, 1999
						Fahr, 2003

State: B'

Energy (cm^-1)		Med.	References


T_o = 29360	T U	Ar	Graham, Dismuke, et al., 1974
			Chang and Graham, 1982

State: A

Energy (cm^-1)	Med.	Transition	λ_min (nm)	λ_max (nm)	References


T_o = 3692.61	gas				Carrick, Merer, et al., 1983
					Curl, Carrick, et al., 1985
					Yan, Hall, et al., 1987
					Kanamori and Hirota, 1988
					Kawaguchi, Amano, et al., 1988
					Ervin and Lineberger, 1991
					Yan and Amano, 1993
					Hsu, Shiu, et al., 1995
					Pfelzer, Havenith, et al., 1996
					Hsu, Chen, et al., 1996
					Taylor, Xu, et al., 1998, 2
					Chiang and Hsu, 1999
					Boye, Campos, et al., 2002
					Sharp-Williams, Roberts, et al., 2011
T_o = 3685.8	Ne	A-X	1100	2715	Forney, Jacox, et al., 1995
T_o = 3732	Ar				Jacox and Olson, 1987
					Forney, Jacox, et al., 1995

Vib. sym.	No.	Approximate type of mode	cm^-1		Med.	Method	References


Σ⁺	3	CC stretch	1706.2	T	Ne	AB	Forney, Jacox, et al., 1995

State: X

Vib. sym.	No.	Approximate type of mode	cm^-1		Med.	Method	References


Σ⁺	1	CH stretch	3298.85	T	gas	CC	Stephens, Yan, et al., 1988
	1	CH stretch	3293.3		Ne	IR	Wu and Cheng, 2008
Π	2	Bend	371.60		gas	DL PE	Kanamori and Hirota, 1988 Kawaguchi, Amano, et al., 1988 Zhou, Garand, et al., 2007
Σ⁺	3	CC stretch	1840.57		gas	DL	Kanamori, Seki, et al., 1987
	3	CC stretch	1835.5		Ne	IR	Forney, Jacox, et al., 1995 Andrews, Kushto, et al., 1999 Wu and Cheng, 2008
	3	CC stretch	1846.2	m	Ar	IR	Milligan, Jacox, et al., 1967 Jacox, 1975 Shepherd and Graham, 1987 Jacox and Olson, 1987 Andrews, Kushto, et al., 1999
	3	CC stretch	1842		Kr	IR	Tanskanen, Khriachtchev, et al., 2004
	3	CC stretch	1852		Xe	IR	Khriachtchev, Tanskanen, et al., 2003 Feldman, Sukhov, et al., 2003

Additional references: Jacox, 1994, page 32; Jacox, 1998, page 142; Jacox, 2003, page 28; Tucker, Kutner, et al., 1974; Okabe, 1975; Sastry, Helminger, et al., 1981; Ziurys, Saykally, et al., 1982; Gottlieb, Gottlieb, et al., 1983; Saito, Hikida, et al., 1984; Saykally, Veseth, et al., 1984; Suto and Lee, 1984; Fournier, Kaddouri, et al., 1985; Bogey, Demuynck, et al., 1985; Tiee, Sander, et al., 1985; Shokoohi, Watson, et al., 1986; Yan, Dane, et al., 1987; Vervloet and Herman, 1988; Kanamori and Hirota, 1988, 2; Brown and Evenson, 1988; Fletcher and Leone, 1989; Bogey, Demuynck, et al., 1989; Yan, Warner, et al., 1991; Schmidt, Peric, et al., 1998; Chiang and Hsu, 2000; Muller, Klaus, et al., 2000; Tarroni and Carter, 2003; Tarroni and Carter, 2004

Notes

Medium

Upper bound

Tentative assignment or approximate value

Energy separation between the v = 0 levels of the excited and electronic ground states.

References

Go To: Top, Reaction thermochemistry data, Gas phase ion energetics data, Vibrational and/or electronic energy levels, Notes

Ervin, Gronert, et al., 1990
Ervin, K.M.; Gronert, S.; Barlow, S.E.; Gilles, M.K.; Harrison, A.G.; Bierbaum, V.M.; DePuy, C.H.; Lin, W.C., Bonds Strengths of Ethylene and Acetylene, J. Am. Chem. Soc., 1990, 112, 15, 5750, https://doi.org/10.1021/ja00171a013 . [all data]

Kiefer, Sidhu, et al., 1989
Kiefer, J.H.; Sidhu, S.S.; Kumaran, S.S.; Irdan, E.A., RRKM Model of C2H4 Dissociation: Heat of Formation of Vinylidene, Chem. Phys. Lett., 1989, 159, 1, 32, https://doi.org/10.1016/S0009-2614(89)87448-2 . [all data]

Guo and Grabowski, 1990
Guo, Y.; Grabowski, J.J., Gas Phase Ion Chemistry of the Vinylidene Radical Anion and the Acidity of the Vinyl Radical, Int. J. Mass Spectrom. Ion Proc., 1990, 97, 3, 253, https://doi.org/10.1016/0168-1176(90)85003-K . [all data]

Hunter and Lias, 1998
Hunter, E.P.; Lias, S.G., Evaluated Gas Phase Basicities and Proton Affinities of Molecules: An Update, J. Phys. Chem. Ref. Data, 1998, 27, 3, 413-656, https://doi.org/10.1063/1.556018 . [all data]

Zhou, Garand, et al., 2007
Zhou, J.; Garand, E.; Neumark, D.M., Vibronic structure in C2H and C2D from anion slow electron velocity-map imaging spectroscopy, J. Chem. Phys., 2007, 127, 11, 114313, https://doi.org/10.1063/1.2768932 . [all data]

Ervin and Lineberger, 1991
Ervin, K.M.; Lineberger, W.C., Photoelectron Spectra of C2- and C2H-, J. Phys. Chem., 1991, 95, 3, 1167, https://doi.org/10.1021/j100156a026 . [all data]

Taylor, Xu, et al., 1998
Taylor, T.R.; Xu, C.S.; Neumark, D.M., Photoelectron spectra of the C2nH- (n=1-4) and C2nD- (n=1-3) anions, J. Chem. Phys., 1998, 108, 24, 10018-10026, https://doi.org/10.1063/1.476462 . [all data]

Janousek, Brauman, et al., 1979
Janousek, B.K.; Brauman, J.I.; Simons, J., An experimental and theoretical determination of the electron affinity of the enhynyl radical HC₂, J. Chem. Phys., 1979, 71, 2057. [all data]

Thynne and MacNiel, 1971
Thynne, J.C.J.; MacNiel, K.A.G., Negative ion formation by ethylene and 1,1-difluoroethylene, J. Phys. Chem., 1971, 75, 2584. [all data]

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

Locht and Momigny, 1970
Locht, R.; Momigny, J., Mass Spectrometric Determination of the Electron Affinities of Radicals, Chem. Phys. Lett., 1970, 6, 4, 273, https://doi.org/10.1016/0009-2614(70)85072-2 . [all data]

Trepka and Neuert, 1963
Trepka, L.v.; Neuert, H., Uber die Entstehenung von Negativen Ionen aus einigen Kohlenwasserstoffen und Alkoholen durch Elektronenstoss, Z. Naturfor., 1963, 18A, 1295. [all data]

Page and Goode, 1969
Page, F.M.; Goode, G.C., Negative Ions and the Magnetron., Wiley, NY, 1969. [all data]

Norwood and Ng, 1989
Norwood, K.; Ng, C.Y., A state-selected study of the unimolecular decompoisition of C₂H₂⁺(A,B) using the photoion photoelectron coincidence method, J. Chem. Phys., 1989, 91, 2898. [all data]

Lias, Bartmess, et al., 1988
Lias, S.G.; Bartmess, J.E.; Liebman, J.F.; Holmes, J.L.; Levin, R.D.; Mallard, W.G., Gas-phase ion and neutral thermochemistry, J. Phys. Chem. Ref. Data, Suppl. 1, 1988, 17, 1-861. [all data]

Ono and Ng, 1981
Ono, Y.; Ng, C.Y., The heat of formation of C₂H⁺, J. Chem. Phys., 1981, 74, 6985. [all data]

Okabe and Dibeler, 1973
Okabe, H.; Dibeler, V.H., Photon impact studies of C₂HCN and CH₃CN in the vacuum ultraviolet; heats of formation of C₂H and CH₃CN, J. Chem. Phys., 1973, 59, 2430. [all data]

Dibeler, Walker, et al., 1973
Dibeler, V.H.; Walker, J.A.; McCulloh, K.E., Observations on hot bands in the molecular and dissociative photoionization of acetylene and the heat of formation of the ethynyl ion, J. Chem. Phys., 1973, 59, 2264. [all data]

Wyatt and Stafford, 1972
Wyatt, J.R.; Stafford, F.E., Mass spectrometric determination of the heat of formation of ethynyl radical, C₂H, and of some related species, J. Phys. Chem., 1972, 76, 1913. [all data]

Cool and Goodwin, 1991
Cool, T.A.; Goodwin, P.M., Observation of an electronic state of C2H near 9 eV by resonance ionization spectroscopy, J. Chem. Phys., 1991, 94, 11, 6978, https://doi.org/10.1063/1.460231 . [all data]

Chang and Graham, 1982
Chang, K.W.; Graham, W.R.M., Vacuum UV spectra of photolyzed C2H2 in solid Ar at 8 K, J. Chem. Phys., 1982, 76, 11, 5238, https://doi.org/10.1063/1.442919 . [all data]

Hsu, Wang, et al., 1992
Hsu, Y.-C.; Wang, P.-R.; Yang, M.-C.; Papousek, D.; Chen, Y.-T.; Chiang, W.-Y., Ultraviolet laser-induced fluorescence of the C2H radical, Chem. Phys. Lett., 1992, 190, 5, 507, https://doi.org/10.1016/0009-2614(92)85182-A . [all data]

Hsu, Lin, et al., 1993
Hsu, Y.-C.; Lin, J.J.-M.; Papousek, D.; Tsai, J.-J., The low-lying bending vibrational levels of the CCH (X 2Σ+) radical studied by laser-induced fluorescence, J. Chem. Phys., 1993, 98, 9, 6690, https://doi.org/10.1063/1.464761 . [all data]

Some, Remy, et al., 1995
Some, E.; Remy, F.; Macau-Hercot, D.; Dubois, I.; Breton, J.; Bredohl, H., The Near UV Emission Spectrum of C2H, J. Mol. Spectrosc., 1995, 173, 1, 44, https://doi.org/10.1006/jmsp.1995.1216 . [all data]

Hsu, Shiu, et al., 1995
Hsu, Y.-C.; Shiu, Y.-J.; Lin, C.-M., Laser-induced fluorescence spectroscopy of CCH (X 2Σ+) in vibrationally excited levels up to 4500 cm-1, J. Chem. Phys., 1995, 103, 14, 5919, https://doi.org/10.1063/1.470472 . [all data]

Chiang and Hsu, 1999
Chiang, W.-Y.; Hsu, Y.-C., Laser spectroscopy of CCH in the 36 600--39 700 cm[sup -1] region, J. Chem. Phys., 1999, 111, 4, 1454, https://doi.org/10.1063/1.479389 . [all data]

Fahr, 2003
Fahr, A., Ultraviolet absorption spectrum and cross-sections of ethynyl (C2H) radicals, J. Mol. Spectrosc., 2003, 217, 2, 249, https://doi.org/10.1016/S0022-2852(02)00039-5 . [all data]

Graham, Dismuke, et al., 1974
Graham, W.R.M.; Dismuke, K.I.; Weltner, W., Jr., C2H radical: 13C hyperfine interaction and optical spectrum, J. Chem. Phys., 1974, 60, 10, 3817, https://doi.org/10.1063/1.1680824 . [all data]

Carrick, Merer, et al., 1983
Carrick, P.G.; Merer, A.J.; Curl, R.F., A 2Π←X 2Σ+ infrared electronic transition of C2Ha), J. Chem. Phys., 1983, 78, 6, 3652, https://doi.org/10.1063/1.445112 . [all data]

Curl, Carrick, et al., 1985
Curl, R.F.; Carrick, P.G.; Merer, A.J., Rotational analysis of the A ← X system of C2Ha), J. Chem. Phys., 1985, 82, 8, 3479, https://doi.org/10.1063/1.448927 . [all data]

Yan, Hall, et al., 1987
Yan, W.-B.; Hall, J.L.; Stephens, J.W.; Richnow, M.L.; Curl, R.F., Color center laser spectroscopy of vibrationally excited C2H, J. Chem. Phys., 1987, 86, 4, 1657, https://doi.org/10.1063/1.452163 . [all data]

Kanamori and Hirota, 1988
Kanamori, H.; Hirota, E., Vibronic bands of the CCH radical observed by infrared diode laser kinetic spectroscopy, J. Chem. Phys., 1988, 89, 7, 3962, https://doi.org/10.1063/1.454877 . [all data]

Kawaguchi, Amano, et al., 1988
Kawaguchi, K.; Amano, T.; Hirota, E., Infrared diode laser spectroscopy of the ν2 + ν3 band of CCH, J. Mol. Spectrosc., 1988, 131, 1, 58, https://doi.org/10.1016/0022-2852(88)90106-3 . [all data]

Yan and Amano, 1993
Yan, W.-B.; Amano, T., Difference-frequency laser spectroscopy of the 3ν2+ν3 band of C2H, J. Chem. Phys., 1993, 99, 6, 4312, https://doi.org/10.1063/1.466084 . [all data]

Pfelzer, Havenith, et al., 1996
Pfelzer, C.; Havenith, M.; Peric, M.; Murtz, P.; Urban, W., Faraday Laser Magnetic Resonance Spectroscopy of Vibrationally Excited C2H, J. Mol. Spectrosc., 1996, 176, 1, 28, https://doi.org/10.1006/jmsp.1996.0058 . [all data]

Hsu, Chen, et al., 1996
Hsu, Y.-C.; Chen, F.-T.; Chou, L.-C.; Shiu, Y.-J., 193.3 nm photodissociation of acetylene: Nascent state distribution of CCH radical studied by laser-induced fluorescence, J. Chem. Phys., 1996, 105, 20, 9153, https://doi.org/10.1063/1.472763 . [all data]

Taylor, Xu, et al., 1998, 2
Taylor, T.R.; Xu, C.; Neumark, D.M., Photoelectron spectra of the C[sub 2n]H[sup -] (n=1--4) and C[sub 2n]D[sup -] (n=1--3) anions, J. Chem. Phys., 1998, 108, 24, 10018, https://doi.org/10.1063/1.476462 . [all data]

Boye, Campos, et al., 2002
Boye, S.; Campos, A.; Douin, S.; Fellows, C.; Gauyacq, D.; Shafizadeh, N.; Halvick, Ph.; Boggio-Pasqua, M., Visible emission from the vibrationally hot C[sub 2]H radical following vacuum-ultraviolet photolysis of acetylene: Experiment and theory, J. Chem. Phys., 2002, 116, 20, 8843, https://doi.org/10.1063/1.1471239 . [all data]

Sharp-Williams, Roberts, et al., 2011
Sharp-Williams, E.N.; Roberts, M.A.; Nesbitt, D.J., High resolution slit-jet infrared spectroscopy of ethynyl radical: 2Π--2Σ+ vibronic bands with sub-Doppler resolution, J. Chem. Phys., 2011, 134, 6, 064314, https://doi.org/10.1063/1.3532088 . [all data]

Forney, Jacox, et al., 1995
Forney, D.; Jacox, M.E.; Thompson, W.E., The Infrared and Near-Infrared Spectra of HCC and DCC Trapped in Solid Neon, J. Mol. Spectrosc., 1995, 170, 1, 178, https://doi.org/10.1006/jmsp.1995.1065 . [all data]

Jacox and Olson, 1987
Jacox, M.E.; Olson, W.B., The A 2Π--X 2Σ+ transition of HC2 isolated in solid argon, J. Chem. Phys., 1987, 86, 6, 3134, https://doi.org/10.1063/1.452024 . [all data]

Stephens, Yan, et al., 1988
Stephens, J.W.; Yan, W.-B.; Richnow, M.L.; Solka, H.; Curl, R.F., Infrared kinetic spectroscopy of C2H and C2D, J. Mol. Struct., 1988, 190, 41, https://doi.org/10.1016/0022-2860(88)80269-2 . [all data]

Wu and Cheng, 2008
Wu, Y.-J.; Cheng, B.-M., Infrared absorption spectra of ethynyl radicals isolated in solid Ne: Identification of the fundamental C--H stretching mode, Chem. Phys. Lett., 2008, 461, 1-3, 53, https://doi.org/10.1016/j.cplett.2008.07.008 . [all data]

Kanamori, Seki, et al., 1987
Kanamori, H.; Seki, K.; Hirota, E., Infrared diode laser kinetic spectroscopy of the CCH radical ν3 band, J. Chem. Phys., 1987, 87, 1, 73, https://doi.org/10.1063/1.453571 . [all data]

Andrews, Kushto, et al., 1999
Andrews, L.; Kushto, G.P.; Zhou, M.; Willson, S.P.; Souter, P.F., Infrared spectrum of CCH[sup +] in solid argon and neon, J. Chem. Phys., 1999, 110, 9, 4457, https://doi.org/10.1063/1.478329 . [all data]

Milligan, Jacox, et al., 1967
Milligan, D.E.; Jacox, M.E.; Abouaf-Marguin, L., Vacuum-Ultraviolet Photolysis of Acetylene in Inert Matrices. Spectroscopic Study of the Species C2, J. Chem. Phys., 1967, 46, 12, 4562, https://doi.org/10.1063/1.1840602 . [all data]

Jacox, 1975
Jacox, M.E., Matrix isolation study of the vibrational spectrum and structure of HC2, Chem. Phys., 1975, 7, 3, 424, https://doi.org/10.1016/0301-0104(75)87025-X . [all data]

Shepherd and Graham, 1987
Shepherd, R.A.; Graham, W.R.M., FTIR study of D and 13C substituted C2H in solid argon, J. Chem. Phys., 1987, 86, 5, 2600, https://doi.org/10.1063/1.452062 . [all data]

Tanskanen, Khriachtchev, et al., 2004
Tanskanen, H.; Khriachtchev, L.; Lundell, J.; Rasanen, M., Organo-noble-gas hydride compounds HKrCCH, HXeCCH, HXeCC, and HXeCCXeH: Formation mechanisms and effect of [sup 13]C isotope substitution on the vibrational properties, J. Chem. Phys., 2004, 121, 17, 8291, https://doi.org/10.1063/1.1799611 . [all data]

Khriachtchev, Tanskanen, et al., 2003
Khriachtchev, L.; Tanskanen, H.; Lundell, J.; Pettersson, M.; Kiljunen, H.; Rasanen, M., Fluorine-Free Organoxenon Chemistry: HXeCCH, HXeCC, and HXeCCXeH, J. Am. Chem. Soc., 2003, 125, 16, 4696, https://doi.org/10.1021/ja034485d . [all data]

Feldman, Sukhov, et al., 2003
Feldman, V.I.; Sukhov, F.F.; Orlov, A.Yu.; Tyulpina, I.V., Experimental Evidence for the Formation of HXeCCH: The First Hydrocarbon with an Inserted Rare-Gas Atom, J. Am. Chem. Soc., 2003, 125, 16, 4698, https://doi.org/10.1021/ja034585j . [all data]

Jacox, 1994
Jacox, M.E., Vibrational and electronic energy levels of polyatomic transient molecules, American Chemical Society, Washington, DC, 1994, 464. [all data]

Jacox, 1998
Jacox, M.E., Vibrational and electronic energy levels of polyatomic transient molecules: supplement A, J. Phys. Chem. Ref. Data, 1998, 27, 2, 115-393, https://doi.org/10.1063/1.556017 . [all data]

Jacox, 2003
Jacox, M.E., Vibrational and electronic energy levels of polyatomic transient molecules: supplement B, J. Phys. Chem. Ref. Data, 2003, 32, 1, 1-441, https://doi.org/10.1063/1.1497629 . [all data]

Tucker, Kutner, et al., 1974
Tucker, K.D.; Kutner, M.L.; Thaddeus, P., The ethynyl radical C2H - A new interstellar molecule, Astrophys. J., 1974, 193, L115, https://doi.org/10.1086/181646 . [all data]

Okabe, 1975
Okabe, H., J. Chem. Phys., 1975, 62, 2782. [all data]

Sastry, Helminger, et al., 1981
Sastry, K.V.L.N.; Helminger, P.; Charo, A.; Herbst, E.; De Lucia, F.C., Laboratory millimeter and submillimeter spectrum of CCH, Astrophys. J., 1981, 251, L119, https://doi.org/10.1086/183706 . [all data]

Ziurys, Saykally, et al., 1982
Ziurys, L.M.; Saykally, R.J.; Plambeck, R.L.; Erickson, N.R., Detection of the N = 3-2 transition of CCH in Orion and determination of the molecular rotational constants, Astrophys. J., 1982, 254, 94, https://doi.org/10.1086/159709 . [all data]

Gottlieb, Gottlieb, et al., 1983
Gottlieb, C.A.; Gottlieb, E.W.; Thaddeus, P., Laboratory and astronomical measurement of the millimeter wave spectrum of the ethynyl radical CCH, Astrophys. J., 1983, 264, 740, https://doi.org/10.1086/160647 . [all data]

Saito, Hikida, et al., 1984
Saito, Y.; Hikida, T.; Ichimura, T.; Mori, Y., Fluorescence of excited ethynyl radicals produced by pulsed vacuum ultraviolet photolyses of C2H2, C2D2, and C2HBr, J. Chem. Phys., 1984, 80, 1, 31, https://doi.org/10.1063/1.446448 . [all data]

Saykally, Veseth, et al., 1984
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Notes

Go To: Top, Reaction thermochemistry data, Gas phase ion energetics data, Vibrational and/or electronic energy levels, References

Symbols used in this document:

EA Electron affinity

IE (evaluated) Recommended ionization energy

Δ_rG° Free energy of reaction at standard conditions

Δ_rH° Enthalpy of reaction at standard conditions
Data from NIST Standard Reference Database 69: NIST Chemistry WebBook
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EA	Electron affinity
IE (evaluated)	Recommended ionization energy
Δ_rG°	Free energy of reaction at standard conditions
Δ_rH°	Enthalpy of reaction at standard conditions