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Gas phase ion energetics 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.

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
LBLHLM - Sharon G. Lias, John E. Bartmess, Joel F. Liebman, John L. Holmes, Rhoda D. Levin, and W. Gary Mallard
LLK - Sharon G. Lias, Rhoda D. Levin, and Sherif A. Kafafi
RDSH - Henry M. Rosenstock, Keith Draxl, Bruce W. Steiner, and John T. Herron

View reactions leading to CH4+ (ion structure unspecified)

Quantity Value Units Method Reference Comment
IE (evaluated)12.61 ± 0.01eVN/AN/AL
Quantity Value Units Method Reference Comment
Proton affinity (review)543.5kJ/molN/AHunter and Lias, 1998HL
Quantity Value Units Method Reference Comment
Gas basicity520.6kJ/molN/AHunter and Lias, 1998HL

Ionization energy determinations

IE (eV) Method Reference Comment
12.61 ± 0.01PIBerkowitz, Greene, et al., 1987LBLHLM
12.6 ± 0.4EIChatham, Hils, et al., 1984LBLHLM
12.63 ± 0.02EIPlessis, Marmet, et al., 1983LBLHLM
13.6PEKimura, Katsumata, et al., 1981LLK
12.75 ± 0.02PEBieri, Burger, et al., 1977LLK
12.82 ± 0.02EISelim and El-Kholy, 1975LLK
12.6PEDebies and Rabalais, 1975LLK
12.6PIRabalais, Debies, et al., 1974LLK
12.8EIMorrison and Traeger, 1973LLK
12.64PEPotts and Price, 1972LLK
12.94 ± 0.04EIFinney and Harrison, 1972LLK
12.51PEBergmark, Rabalais, et al., 1972LLK
~12.51PERabalais, Bergmark, et al., 1971LLK
≤12.615 ± 0.010PIChupka and Berkowitz, 1971LLK
12.78PEPullen, Carlson, et al., 1970RDSH
12.75PEBrundle, Robin, et al., 1970RDSH
≤12.70EILossing and Semeluk, 1969RDSH
12.99 ± 0.05EIWilliams and Hamill, 1968RDSH
12.75 ± 0.05TEVillarejo, Stockbauer, et al., 1968RDSH
12.9CICermak, 1968RDSH
12.70PEBaker, Baker, et al., 1968RDSH
12.55 ± 0.05PIBrehm, 1966RDSH
12.704 ± 0.008PINicholson, 1965RDSH
12.71 ± 0.02PIDibeler, Krauss, et al., 1965RDSH
13.00 ± 0.02EIMelton and Hamill, 1964RDSH
13.6PEBieri and Asbrink, 1980Vertical value; LLK
13.6 ± 0.1PEBieri, Burger, et al., 1977Vertical value; LLK
13.60EIHarshbarger, Robin, et al., 1973Vertical value; LLK

Appearance energy determinations

Ion AE (eV) Other Products MethodReferenceComment
C+25. ± 2.?EIChatham, Hils, et al., 1984LBLHLM
C+19.56 ± 0.202H2EIPlessis, Marmet, et al., 1983LBLHLM
C+≤25.2?EIMorrison and Traeger, 1973LLK
CH+22.2 ± 0.4?EIChatham, Hils, et al., 1984LBLHLM
CH+19.11 ± 0.20H-+H2EIPlessis, Marmet, et al., 1983LBLHLM
CH+19.87 ± 0.20H+H2EIPlessis, Marmet, et al., 1983LBLHLM
CH+22.4H2+H?EIMorrison and Traeger, 1973LLK
CH2+15.1 ± 0.4H2EIChatham, Hils, et al., 1984LBLHLM
CH2+15.06 ± 0.02H2EIPlessis, Marmet, et al., 1983LBLHLM
CH2+15.16 ± 0.02H2PIMcCulloh and Dibeler, 1976T = 0K; LLK
CH2+15.3H2EIMorrison and Traeger, 1973LLK
CH2+15.19 ± 0.02H2PIChupka, 1968RDSH
CH2+15.16 ± 0.04H2PIDibeler, Krauss, et al., 1965RDSH
CH3+14.3 ± 0.4HEIChatham, Hils, et al., 1984LBLHLM
CH3+13.25 ± 0.08H-EIPlessis, Marmet, et al., 1983LBLHLM
CH3+14.01 ± 0.08HEIPlessis, Marmet, et al., 1983LBLHLM
CH3+14.30HPIPECOStockbauer, 1977LLK
CH3+14.324 ± 0.003HPIMcCulloh and Dibeler, 1976T = 0K; LLK
CH3+14.4HEIMorrison and Traeger, 1973LLK
CH3+14.30HEILossing and Semeluk, 1970RDSH
CH3+14.24 ± 0.05HEIWilliams and Hamill, 1968RDSH
CH3+13.50 ± 0.05H-PIChupka, 1968RDSH
CH3+14.320 ± 0.004HPIChupka, 1968RDSH
CH3+14.23 ± 0.05HPIBrehm, 1966RDSH
CH3+14.25 ± 0.02HPIDibeler, Krauss, et al., 1965RDSH
H+21.3 ± 0.3CH3EILocht, Olivier, et al., 1979LLK
H+24.0 ± 0.5CH3EIAppell and Kubach, 1971LLK

De-protonation reactions

CH3- + Hydrogen cation = Methane

By formula: CH3- + H+ = CH4

Quantity Value Units Method Reference Comment
Δr1743.6 ± 2.9kJ/molD-EAEllison, Engelking, et al., 1978gas phase; B
Δr1749. ± 15.kJ/molCIDTGraul and Squires, 1990gas phase; B
Δr>1691.1 ± 0.42kJ/molG+TSBohme, Lee-Ruff, et al., 1972gas phase; B
Δr1735.5kJ/molN/ACheck, Faust, et al., 2001gas phase; FeBr3; ; ΔS(EA)=9.3; B
Quantity Value Units Method Reference Comment
Δr1709.8 ± 3.3kJ/molH-TSEllison, Engelking, et al., 1978gas phase; B
Δr1715. ± 15.kJ/molH-TSGraul and Squires, 1990gas phase; B
Δr>1657.3kJ/molIMRBBohme, Lee-Ruff, et al., 1972gas phase; B
Δr1704.1kJ/molN/ACheck, Faust, et al., 2001gas phase; FeBr3; ; ΔS(EA)=9.3; B


Go To: Top, Gas phase ion energetics data, Notes

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

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, . [all data]

Berkowitz, Greene, et al., 1987
Berkowitz, J.; Greene, J.P.; Cho, H.; Ruscic, B., The ionization potentials of CH4 and CD4, J. Chem. Phys., 1987, 86, 674. [all data]

Chatham, Hils, et al., 1984
Chatham, H.; Hils, D.; Robertson, R.; Gallagher, A., Total and partial electron collisional ionization cross sections for CH4, C2H6, SiH4, and Si2H6, J. Chem. Phys., 1984, 81, 1770. [all data]

Plessis, Marmet, et al., 1983
Plessis, P.; Marmet, P.; Dutil, R., Ionization and appearance potentials of CH4 by electron impact, J. Phys. B:, 1983, 16, 1283. [all data]

Kimura, Katsumata, et al., 1981
Kimura, K.; Katsumata, S.; Achiba, Y.; Yamazaki, T.; Iwata, S., Ionization energies, Ab initio assignments, and valence electronic structure for 200 molecules in Handbook of HeI Photoelectron Spectra of Fundamental Organic Compounds, Japan Scientific Soc. Press, Tokyo, 1981. [all data]

Bieri, Burger, et al., 1977
Bieri, G.; Burger, F.; Heilbronner, E.; Maier, J.P., Valence ionization enrgies of hydrocarbons, Helv. Chim. Acta, 1977, 60, 2213. [all data]

Selim and El-Kholy, 1975
Selim, E.T.M.; El-Kholy, S.B., Mass spectrometric ionization and dissociation of methane, Indian J. Pure Appl. Phys., 1975, 13, 233. [all data]

Debies and Rabalais, 1975
Debies, T.P.; Rabalais, J.W., Calculated photoionization cross-sections and angular distributions for the isoelectronic series Ne, HF, H2O, NH3, and CH4, J. Am. Chem. Soc., 1975, 97, 487. [all data]

Rabalais, Debies, et al., 1974
Rabalais, J.W.; Debies, T.P.; Berkosky, J.L.; Huang, J.-T.J.; Ellison, F.O., Calculated photoionization cross sections relative experimental photoionization intensities for a selection of small molecules, J. Chem. Phys., 1974, 61, 516. [all data]

Morrison and Traeger, 1973
Morrison, J.D.; Traeger, J.C., Ionization and dissociation by electron impact. III. CH4 and SiH4, Int. J. Mass Spectrom. Ion Phys., 1973, 11, 289. [all data]

Potts and Price, 1972
Potts, A.W.; Price, W.C., The photoelectron spectra of methane, silane germane and stannane, Proc. R. Soc. London A:, 1972, 165. [all data]

Finney and Harrison, 1972
Finney, C.D.; Harrison, A.G., A third-derivative method for determining electron-impact onset potentials, Int. J. Mass Spectrom. Ion Phys., 1972, 9, 221. [all data]

Bergmark, Rabalais, et al., 1972
Bergmark, T.; Rabalais, J.W.; Werme, L.O.; Karlsson, L.; Siegbahn, K., High-resolution electron spectra of methane, thiophene, 2-bromothiphene, and 3-bromothiophene in Electron Spectroscopy, ed. D.A. Shirley (North-Holland Pub. Co., Amsterdam), 1972. [all data]

Rabalais, Bergmark, et al., 1971
Rabalais, J.W.; Bergmark, T.; Werme, L.O.; Karlsson, L.; Siegbahn, K., The Jahn-Teller effect in the electron spectrum of methane, Phys. Scr., 1971, 3, 13. [all data]

Chupka and Berkowitz, 1971
Chupka, W.A.; Berkowitz, J., Photoionization of methane: ionization potential and proton affinity of CH4, J. Chem. Phys., 1971, 54, 4256. [all data]

Pullen, Carlson, et al., 1970
Pullen, B.P.; Carlson, T.A.; Moddeman, W.E.; Schweitzer, G.K.; Bull, W.E., Photoelectron spectra of methane, silane, germane, methyl fluoride, difluoromethane, and trifluoromethane, J. Chem. Phys., 1970, 53, 768. [all data]

Brundle, Robin, et al., 1970
Brundle, C.R.; Robin, M.B.; Basch, H., Electronic energies and electronic structures of the fluoromethanes, J. Chem. Phys., 1970, 53, 2196. [all data]

Lossing and Semeluk, 1969
Lossing, F.P.; Semeluk, G.P., Threshold ionization efficiency curves for monoenergetic electron impact on H2, D2, CH4 and CD4, Intern. J. Mass Spectrom. Ion Phys., 1969, 2, 408. [all data]

Williams and Hamill, 1968
Williams, J.M.; Hamill, W.H., Ionization potentials of molecules and free radicals and appearance potentials by electron impact in the mass spectrometer, J. Chem. Phys., 1968, 49, 4467. [all data]

Villarejo, Stockbauer, et al., 1968
Villarejo, D.; Stockbauer, R.; Inghram, M.G., Measurement of threshold electrons in the photoionization of small molecules, Bull. Am. Phys. Soc., 1968, 13, 39. [all data]

Cermak, 1968
Cermak, V., Penning ionization electron spectroscopy. I. Determination of ionization potentials of polyatomic molecules, Collection Czech. Chem. Commun., 1968, 33, 2739. [all data]

Baker, Baker, et al., 1968
Baker, A.D.; Baker, C.; Brundle, C.R.; Turner, D.W., The electronic structures of methane, ethane, ethylene and formaldehyde studied by high-resolution molecular photoelectron spectroscopy, Intern. J. Mass Spectrom. Ion Phys., 1968, 1, 285. [all data]

Brehm, 1966
Brehm, B., Massenspektrometrische Untersuchung der Photoionisation von Molekulen, Z. Naturforsch., 1966, 21a, 196. [all data]

Nicholson, 1965
Nicholson, A.J.C., Photoionization-efficiency curves. II. False and genuine structure, J. Chem. Phys., 1965, 43, 1171. [all data]

Dibeler, Krauss, et al., 1965
Dibeler, V.H.; Krauss, M.; Reese, R.M.; Harllee, F.N., Mass-spectrometric study of photoionization. III. Methane and methane-d4, J. Chem. Phys., 1965, 42, 3791. [all data]

Melton and Hamill, 1964
Melton, C.E.; Hamill, W.H., Appearance potentials by the retarding potential-difference method for secondary ions produced by excited-neutral, excited ion-neutral, and ion-neutral reactions, J. Chem. Phys., 1964, 41, 1469. [all data]

Bieri and Asbrink, 1980
Bieri, G.; Asbrink, L., 30.4-nm He(II) photoelectron spectra of organic molecules, J. Electron Spectrosc. Relat. Phenom., 1980, 20, 149. [all data]

Harshbarger, Robin, et al., 1973
Harshbarger, W.R.; Robin, M.B.; Lassettre, E.N., The electron impact spectra of the fluoromethanes, J. Electron Spectrosc. Relat. Phenom., 1973, 1, 319. [all data]

McCulloh and Dibeler, 1976
McCulloh, K.E.; Dibeler, V.H., Enthalpy of formation of methyl and methylene radicals of photoionization studies of methane and ketene, J. Chem. Phys., 1976, 64, 4445. [all data]

Chupka, 1968
Chupka, W.A., Mass-spectrometric study of the photoionization of methane, J. Chem. Phys., 1968, 48, 2337. [all data]

Stockbauer, 1977
Stockbauer, R., A threshold photoelectron-photoion coincidence mass spectrometer for measureing ion kinetic energy release on fragmentation, Int. J. Mass Spectrom. Ion Processes, 1977, 25, 89. [all data]

Lossing and Semeluk, 1970
Lossing, F.P.; Semeluk, G.P., Free radicals by mass spectrometry. XLII.Ionization potentials and ionic heats of formation for C1-C4 alkyl radicals, Can. J. Chem., 1970, 48, 955. [all data]

Locht, Olivier, et al., 1979
Locht, R.; Olivier, J.L.; Momigny, J., Dissociative autoionization as a mechanism for the proton formation from methane and methane-d4 by low energy electron impact, Chem. Phys., 1979, 43, 425. [all data]

Appell and Kubach, 1971
Appell, J.; Kubach, C., On the formation of energetic protons by electron impact on methane, Chem. Phys. Lett., 1971, 11, 486. [all data]

Ellison, Engelking, et al., 1978
Ellison, G.B.; Engelking, P.C.; Lineberger, W.C., An experimental determination of the geometry and electron affinity of CH3, J. Am. Chem. Soc., 1978, 100, 2556. [all data]

Graul and Squires, 1990
Graul, S.T.; Squires, R.R., Gas-Phase Acidities Derived from Threshold Energies for Activated Reactions, J. Am. Chem. Soc., 1990, 112, 7, 2517, . [all data]

Bohme, Lee-Ruff, et al., 1972
Bohme, D.K.; Lee-Ruff, E.; Young, L.B., Acidity order of selected bronsted acids in the gas phase at 300K, J. Am. Chem. Soc., 1972, 94, 5153. [all data]

Check, Faust, et al., 2001
Check, C.E.; Faust, T.O.; Bailey, J.M.; Wright, B.J.; Gilbert, T.M.; Sunderlin, L.S., Addition of Polarization and Diffuse Functions to the LANL2DZ Basis Set for P-Block Elements, J. Phys. Chem. A,, 2001, 105, 34, 8111, . [all data]


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