Methylene

• Formula: CH₂
• Molecular weight: 14.0266
• IUPAC Standard InChI: InChI=1S/CH2/h1H2 Copy

  
• IUPAC Standard InChIKey: HZVOZRGWRWCICA-UHFFFAOYSA-N Copy
• CAS Registry Number: 2465-56-7
• 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.
• Isotopologues:
  • CD2
• Permanent link for this species. Use this link for bookmarking this species for future reference.
• Information on this page:
  • Gas phase thermochemistry data
  • Gas phase ion energetics data
  • Vibrational and/or electronic energy levels
  • References
  • Notes
• Other data available:
  • Reaction thermochemistry data
  • Ion clustering data
• Data at other public NIST sites:
  • Microwave spectra (on physics lab web site)
  • Electron-Impact Ionization Cross Sections (on physics web site)
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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.

Gas Phase Heat Capacity (Shomate Equation)

C_p° = 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
    C_p = heat capacity (cal/mol*K)
    H° = standard enthalpy (kcal/mol)
    S° = standard entropy (cal/mol*K)
    t = temperature (K) / 1000.

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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:
L - Sharon G. Lias

Data compiled as indicated in comments:
B - John E. Bartmess
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 CH₂⁺ (ion structure unspecified)

Electron affinity determinations

Ionization energy determinations

De-protonation reactions

CH^- +  =

By formula: CH^- + H⁺ = CH₂

Vibrational and/or electronic energy levels

Go To: Top, Gas phase thermochemistry data, Gas phase ion energetics 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: Marilyn E. Jacox

State:   4p

State:   D

State:   C

State:   3d ³A₂

State:   3p

State:   c

State:   b

State:   a

State:   X

Additional references: Jacox, 1994, page 18; Jacox, 1998, page 130; Jacox, 2003, page 16; Herzberg, 1961; Bernheim, Bernard, et al., 1970; Wasserman, Yager, et al., 1970; Wasserman, Kuck, et al., 1970; Herzberg and Johns, 1971; Mohlmann and DeHeer, 1976; Grimley and Stephenson, 1981; Ashfold, Fullstone, et al., 1982; Duxbury, 1982; Sears, Bunker, et al., 1982, 2; Jensen, Bunker, et al., 1982; Bunker, Sears, et al., 1983; Evenson, Sears, et al., 1984; Duxbury, 1988; Alijah and Duxbury, 1990; Garcia-Moreno, Lovejoy, et al., 1993; Xie and Dai, 1993; Ozeki and Saito, 1996; Michael, Lewen, et al., 2003; Brunken, Michael, et al., 2004; Brunken, Muller, et al., 2005

Notes

References

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

Leopold, Murray, et al., 1985
Leopold, D.G.; Murray, K.K.; Miller, A.E.S.; Lineberger, W.C., Methylene: A study of the X3B1 and the 1A1 states by photoelectron spectroscopy of CH₂^- and CD₂^-, J. Chem. Phys., 1985, 83, 4849. [all data]

Feldman, Rackwitz, et al., 1977
Feldman, D.; Rackwitz, R.; Kaiser, H.J.; Heincke, E., Photodetachment bei einigen neagtiven molekulionen: P₂-, As₂-, CH₂-, CH₃-, S₃-, Z. Naturforsch. A:, 1977, 32, 600. [all data]

Engelking, Corderman, et al., 1981
Engelking, P.E.; Corderman, R.R.; Wenddoski, J.J.; Ellison, G.B.; O'Niel, V.S.; Lineberger, W.C., Laser photoelectron spectroscopy of CH₂-, and the singlet-triplet splitting in methylene, J. Chem. Phys., 1981, 74, 5460. [all data]

Zittel, Ellison, et al., 1976
Zittel, P.F.; Ellison, G.B.; O'Neil, S.V.; Herbst, E.; Lineberger, W.C.; Reinhardt, W.P., Laser photoelectron spectrometry of CH₂^-. Singlet-triplet splitting and electron affinity of CH₂₁, J. Am. Chem. Soc., 1976, 98, 3731. [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]

Reineke and Strein, 1976
Reineke, W.; Strein, K., Erzeugung eines methylenhaltigen Molekularstrahls durch Pyrolyse von Keten, Ber. Bunsen-Ges. Phys. Chem., 1976, 80, 343. [all data]

Niehaus, 1967
Niehaus, A., Anregung und Dissoziation von Molekulen beim Elektronenbeschuss. Messung der Bildungswahrscheinlichkeit fur neutrale Fragmente als Funktion der Elektronenenergie., Z. Naturforsch., 1967, 22a, 690. [all data]

Herzberg, 1961
Herzberg, G., The ionization potential of CH₂, Can J. Phys., 1961, 39, 1511. [all data]

Kasdan, Herbst, et al., 1975
Kasdan, A.; Herbst, E.; Lineberger, W.C., Laser photoelectron spectrometry of CH₂^-, Chem. Phys. Lett., 1975, 31, 78. [all data]

Irikura, Johnson, et al., 1992
Irikura, K.K.; Johnson, R.D., III; Hudgens, J.W., Two new electronic states of methylene, J. Phys. Chem., 1992, 96, 15, 6131, https://doi.org/10.1021/j100194a010 . [all data]

Herzberg, 1961, 2
Herzberg, G., The Bakerian Lecture. The Spectra and Structures of Free Methyl and Free Methylene, Proc. Roy. Soc. (London) A262, 1961, 262, 1310, 291, https://doi.org/10.1098/rspa.1961.0120 . [all data]

Irikura and Hudgens, 1992
Irikura, K.K.; Hudgens, J.W., Detection of methylene (~X 3B1) radicals by 3 + 1 resonance-enhanced multiphoton ionization spectroscopy, J. Phys. Chem., 1992, 96, 2, 518, https://doi.org/10.1021/j100181a006 . [all data]

Herzberg and Johns, 1966
Herzberg, G.; Johns, J.W.C., The Spectrum and Structure of Singlet CH$_2$, Proc. Roy. Soc.(London) A295, 1966, 295, 1441, 107, https://doi.org/10.1098/rspa.1966.0229 . [all data]

Kim, Komissarov, et al., 2005
Kim, Y.; Komissarov, A.V.; Hall, G.E.; Sears, T.J., Observation of the c [sup 1]A[sub 1] state of methylene by optical-optical double resonance, J. Chem. Phys., 2005, 123, 2, 024306, https://doi.org/10.1063/1.1988289 . [all data]

Kim, Hall, et al., 2006
Kim, Y.; Hall, G.E.; Sears, T.J., Observation of the state of CH2 by optical--optical double resonance, J. Mol. Spectrosc., 2006, 240, 2, 269, https://doi.org/10.1016/j.jms.2006.10.008 . [all data]

McKellar, Bunker, et al., 1983
McKellar, A.R.W.; Bunker, P.R.; Sears, T.J.; Evenson, K.M.; Saykally, R.J.; Langhoff, S.R., Far infrared laser magnetic resonance of singlet methylene: Singlet--triplet perturbations, singlet--triplet transitions, and the singlet--triplet splittinga), J. Chem. Phys., 1983, 79, 11, 5251, https://doi.org/10.1063/1.445713 . [all data]

Petek, Nesbitt, et al., 1987
Petek, H.; Nesbitt, D.J.; Darwin, D.C.; Moore, C.B., Visible absorption and magnetic-rotation spectroscopy of 1CH2: The analysis of the b 1B1 state, J. Chem. Phys., 1987, 86, 3, 1172, https://doi.org/10.1063/1.452263 . [all data]

Green, Chen, et al., 1989
Green, W.H., Jr.; Chen, I.-C.; Bitto, H.; Guyer, D.R.; Moore, C.B., New vibrational bands of CH2 (), J. Mol. Spectrosc., 1989, 138, 2, 614, https://doi.org/10.1016/0022-2852(89)90022-2 . [all data]

Hartland, Xie, et al., 1992
Hartland, G.V.; Xie, W.; Qin, D.; Dai, H-L., Strong asymmetry induced ΔKa=3 transitions in the CH2 b 1B1→a 1A1 spectrum: A study by Fourier transform emission spectroscopy, J. Chem. Phys., 1992, 97, 9, 7010, https://doi.org/10.1063/1.463209 . [all data]

Hartland, Qin, et al., 1993
Hartland, G.V.; Qin, D.; Dai, H.-L., Fourier transform dispersed fluorescence spectroscopy: Observation of new vibrational levels in the 5000--8000 cm-1 region of a 1A1 CH2, J. Chem. Phys., 1993, 98, 3, 2469, https://doi.org/10.1063/1.464176 . [all data]

Garcia-Moreno and Moore, 1993
Garcia-Moreno, I.; Moore, C.B., Spectroscopy of methylene: Einstein coefficients for CH2(b 1B1--a 1A1) transitions, J. Chem. Phys., 1993, 99, 9, 6429, https://doi.org/10.1063/1.465882 . [all data]

Qin, Hartland, et al., 1994
Qin, D.; Hartland, G.V.; Dai, H.-L., A Characterization of the CH2ã1A1(1,2,0),(2,0,0),(0,5,0),(1,3,0) and b1B1(1,142,0),(0,180,0),(0,191,0) Vibronic Levels by Fourier-Transform Dispersed Fluorescence Spectroscopy, J. Mol. Spectrosc., 1994, 168, 2, 333, https://doi.org/10.1006/jmsp.1994.1282 . [all data]

Chang, Wu, et al., 1994
Chang, B.-C.; Wu, M.; Hall, G.E.; Sears, T.J., Near-infrared vibronic spectrum of the CH2 b 1B1←a 1A1 transition, J. Chem. Phys., 1994, 101, 11, 9236, https://doi.org/10.1063/1.468015 . [all data]

Fockenberg, Marr, et al., 1998
Fockenberg, C.; Marr, A.J.; Sears, T.J.; Chang, B.-C., Near-Infrared High Resolution Diode Laser Spectrum of the CH2←ã1A1Transition, J. Mol. Spectrosc., 1998, 187, 2, 119, https://doi.org/10.1006/jmsp.1997.7476 . [all data]

Marr, Sears, et al., 1998
Marr, A.J.; Sears, T.J.; Chang, B.-C., Near-infrared spectroscopy of CH[sub 2] by frequency modulated diode laser absorption, J. Chem. Phys., 1998, 109, 9, 3431, https://doi.org/10.1063/1.476938 . [all data]

Kobayashi, Pride, et al., 2000
Kobayashi, K.; Pride, L.D.; Sears, T.J., Absorption Spectroscopy of Singlet CH, J. Phys. Chem. A, 2000, 104, 45, 10119, https://doi.org/10.1021/jp000293i . [all data]

Kobayashi and Sears, 2001
Kobayashi, K.; Sears, T.J., Can. J. Phys., 2001, 79, 347. [all data]

Hall, Komissarov, et al., 2004
Hall, G.E.; Komissarov, A.V.; Sears, T.J., Doppler-Resolved Spectroscopy as an Assignment Tool in the Spectrum of Singlet Methylene, J. Phys. Chem. A, 2004, 108, 39, 7922, https://doi.org/10.1021/jp0494133 . [all data]

Kobayashi, Hall, et al., 2006
Kobayashi, K.; Hall, G.E.; Sears, T.J., The spectrum of CH[sub 2] near 1.36 and 0.92 μm: Reevaluation of rotational level structure and perturbations in a(010), J. Chem. Phys., 2006, 124, 18, 184320, https://doi.org/10.1063/1.2200340 . [all data]

Chang, Wang, et al., 2011
Chang, C.-H.; Wang, Z.; Hall, G.E.; Sears, T.J.; Xin, J., Transient laser absorption spectroscopy of CH2 near 780nm, J. Mol. Spectrosc., 2011, 267, 1-2, 50, https://doi.org/10.1016/j.jms.2011.02.004 . [all data]

Chang, Xin, et al., 2011
Chang, C.-H.; Xin, J.; Latsha, T.; Otruba, E.; Wang, Z.; Hall, G.E.; Sears, T.J.; Chang, B.-C., CH, J. Phys. Chem. A, 2011, 115, 34, 9440, https://doi.org/10.1021/jp1115965 . [all data]

Bunker and Sears, 1985
Bunker, P.R.; Sears, T.J., Analysis of the laser photoelectron spectrum of CH-2, J. Chem. Phys., 1985, 83, 10, 4866, https://doi.org/10.1063/1.449747 . [all data]

Bunker, Jensen, et al., 1986
Bunker, P.R.; Jensen, P.; Kraemer, W.P.; Beardsworth, R., The potential surface of X 3B1 methylene (CH2) and the singlet--triplet splitting, J. Chem. Phys., 1986, 85, 7, 3724, https://doi.org/10.1063/1.450944 . [all data]

Petek, Nesbitt, et al., 1987, 2
Petek, H.; Nesbitt, D.J.; Moore, C.B.; Birss, F.W.; Ramsay, D.A., Visible absorption and magnetic-rotation spectroscopy of 1CH2: Analysis of the 1A1 state and the 1A1--3B1 coupling, J. Chem. Phys., 1987, 86, 3, 1189, https://doi.org/10.1063/1.452264 . [all data]

Jensen and Bunker, 1988
Jensen, P.; Bunker, P.R., The potential surface and stretching frequencies of X 3B1 methylene (CH2) determined from experiment using the Morse oscillator-rigid bender internal dynamics Hamiltonian, J. Chem. Phys., 1988, 89, 3, 1327, https://doi.org/10.1063/1.455184 . [all data]

Xie, Harkin, et al., 1989
Xie, W.; Harkin, C.; Dai, H.L.; Green, W.H., Jr.; Zheng, Q.K.; Mahoney, A.J., Transient vibrational spectroscopy of, J. Mol. Spectrosc., 1989, 138, 2, 596, https://doi.org/10.1016/0022-2852(89)90020-9 . [all data]

Xie, Harkin, et al., 1990
Xie, W.; Harkin, C.; Dai, H.-L., Bending overtones and barrier height of a 1A1 CH2 by flash photolysis stimulated emission pumping, J. Chem. Phys., 1990, 93, 7, 4615, https://doi.org/10.1063/1.458701 . [all data]

Hartland, Qin, et al., 1995
Hartland, G.V.; Qin, D.; Dai, H.-L., Renner--Teller effect on the highly excited bending levels of a 1A1 CH2, J. Chem. Phys., 1995, 102, 17, 6641, https://doi.org/10.1063/1.469136 . [all data]

Feldman, Meier, et al., 1978
Feldman, D.; Meier, K.; Schmiedl, R.; Welge, K.H., Laser induced fluorescence spectrum of singlet methylene. Spectroscopy of the a~1A1 state, Chem. Phys. Lett., 1978, 60, 1, 30, https://doi.org/10.1016/0009-2614(78)85703-0 . [all data]

Petek, Nesbitt, et al., 1983
Petek, H.; Nesbitt, D.J.; Ogilby, P.R.; Moore, C.B., Infrared flash kinetic spectroscopy: the .nu.1 and .nu.3 spectra of singlet methylene, J. Phys. Chem., 1983, 87, 26, 5367, https://doi.org/10.1021/j150644a012 . [all data]

Petek, Nesbitt, et al., 1989
Petek, H.; Nesbitt, D.J.; Darwin, D.C.; Ogilby, P.R.; Moore, C.B.; Ramsay, D.A., Analysis of CH2 a 1A1 (1,0,0) and (0,0,1) Coriolis-coupled states, a 1A1--X 3B1 spin--orbit coupling, and the equilibrium structure of CH2 a 1A1 state, J. Chem. Phys., 1989, 91, 11, 6566, https://doi.org/10.1063/1.457375 . [all data]

Sears, Bunker, et al., 1981
Sears, T.J.; Bunker, P.R.; McKellar, A.R.W., Observation of the ν2 band of CH2 by laser magnetic resonance, J. Chem. Phys., 1981, 75, 9, 4731, https://doi.org/10.1063/1.442592 . [all data]

Sears, Bunker, et al., 1982
Sears, T.J.; Bunker, P.R.; McKellar, A.R.W., The laser magnetic resonance spectrum of the ν2 band of the methylene radical CH2, J. Chem. Phys., 1982, 77, 11, 5363, https://doi.org/10.1063/1.443784 . [all data]

McKellar, Yamada, et al., 1983
McKellar, A.R.W.; Yamada, C.; Hirota, E., Detection of the ν2 bands of CD2 and CH2 by infrared diode laser spectroscopy, J. Chem. Phys., 1983, 79, 3, 1220, https://doi.org/10.1063/1.445926 . [all data]

Marshall and McKellar, 1986
Marshall, M.D.; McKellar, A.R.W., The ν2 fundamental band of triplet CH2, J. Chem. Phys., 1986, 85, 7, 3716, https://doi.org/10.1063/1.450943 . [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]

Bernheim, Bernard, et al., 1970
Bernheim, R.A.; Bernard, H.W.; Wang, P.S.; Wood, L.S.; Skell, P.S., Electron Paramagnetic Resonance of Triplet CH2, J. Chem. Phys., 1970, 53, 3, 1280, https://doi.org/10.1063/1.1674129 . [all data]

Wasserman, Yager, et al., 1970
Wasserman, E.; Yager, W.A.; Kuck, V.J., EPR of CH2: a substiantially bent and partially rotating ground state triplet, Chem. Phys. Lett., 1970, 7, 4, 409, https://doi.org/10.1016/0009-2614(70)80320-7 . [all data]

Wasserman, Kuck, et al., 1970
Wasserman, E.; Kuck, V.J.; Hutton, R.S.; Yager, W.A., Electron paramagnetic resonance of CD2 and CHD. Isotope effects, motion, and geometry of methylene, J. Am. Chem. Soc., 1970, 92, 25, 7491, https://doi.org/10.1021/ja00728a054 . [all data]

Herzberg and Johns, 1971
Herzberg, G.; Johns, J.W.C., On the Structure of CH2 in its Triplet Ground State, J. Chem. Phys., 1971, 54, 5, 2276, https://doi.org/10.1063/1.1675164 . [all data]

Mohlmann and DeHeer, 1976
Mohlmann, G.R.; DeHeer, F.J., Measurements of the radiative lifetime of CH2(1B1) and absolute CH2(1B1) → 1A1) emission cross sections for electrons (0--2000 eV) on CH4, Chem. Phys. Lett., 1976, 43, 2, 236, https://doi.org/10.1016/0009-2614(76)85293-1 . [all data]

Grimley and Stephenson, 1981
Grimley, A.J.; Stephenson, J.C., Evidence for sequential reactions in the CO2 laser induced multiphoton dissociation of acetic anhydride and acetic acid, J. Chem. Phys., 1981, 74, 1, 447, https://doi.org/10.1063/1.440852 . [all data]

Ashfold, Fullstone, et al., 1982
Ashfold, M.N.R.; Fullstone, M.A.; Hancock, G.; Duxbury, G., Laser induced fluorescence spectroscopy of the CD, Mol. Phys., 1982, 45, 4, 887, https://doi.org/10.1080/00268978200100701 . [all data]

Duxbury, 1982
Duxbury, G., J. Chem. Soc., 1982, Faraday Trans. 2 78, 1433. [all data]

Sears, Bunker, et al., 1982, 2
Sears, T.J.; Bunker, P.R.; McKellar, A.R.W.; Evenson, K.M.; Jennings, D.A.; Brown, J.M., The rotational spectrum and hyperfine structure of the methylene radical CH2 studied by far-infrared laser magnetic resonance spectroscopya), J. Chem. Phys., 1982, 77, 11, 5348, https://doi.org/10.1063/1.443783 . [all data]

Jensen, Bunker, et al., 1982
Jensen, P.; Bunker, P.R.; Hoy, A.R., The equilibrium geometry, potential function, and rotation-vibration energies of CH2 in the X 3B1 ground state, J. Chem. Phys., 1982, 77, 11, 5370, https://doi.org/10.1063/1.443785 . [all data]

Bunker, Sears, et al., 1983
Bunker, P.R.; Sears, T.J.; McKellar, A.R.W.; Evenson, K.M.; Lovas, F.J., The rotational spectrum of the CD2 radical studied by far infrared laser magnetic resonance spectroscopya), J. Chem. Phys., 1983, 79, 3, 1211, https://doi.org/10.1063/1.445925 . [all data]

Evenson, Sears, et al., 1984
Evenson, K.M.; Sears, T.J.; McKellar, A.R.W., Far-infrared laser magnetic resonance of vibrationally excited CD_2, J. Opt. Soc. Amer. B, 1984, 1, 1, 15, https://doi.org/10.1364/JOSAB.1.000015 . [all data]

Duxbury, 1988
Duxbury, G., and Ch. Jungen, 1988, Mol. Phys. 63, 981. [all data]

Alijah and Duxbury, 1990
Alijah, A.; Duxbury, G., Renner-Teller and spin-orbit interactions between the, Mol. Phys., 1990, 70, 4, 605, https://doi.org/10.1080/00268979000102621 . [all data]

Garcia-Moreno, Lovejoy, et al., 1993
Garcia-Moreno, I.; Lovejoy, E.R.; Moore, C.B.; Duxbury, G., Radiative lifetimes of CH2(b 1B1), J. Chem. Phys., 1993, 98, 2, 873, https://doi.org/10.1063/1.464252 . [all data]

Xie and Dai, 1993
Xie, W.; Dai, H.-L., Fluorescence Excitation Spectra of the b1B1 ← ã1A1 2n0 (n = 18-23) Bands of CD2, J. Mol. Spectrosc., 1993, 158, 1, 162, https://doi.org/10.1006/jmsp.1993.1063 . [all data]

Ozeki and Saito, 1996
Ozeki, H.; Saito, S., The microwave spectrum of the CD2 radical, J. Chem. Phys., 1996, 104, 6, 2167, https://doi.org/10.1063/1.470972 . [all data]

Michael, Lewen, et al., 2003
Michael, E.A.; Lewen, F.; Winnewisser, G.; Ozeki, H.; Habara, H.; Herbst, E., Laboratory Spectrum of the 1, Astrophys. J., 2003, 596, 2, 1356, https://doi.org/10.1086/378090 . [all data]

Brunken, Michael, et al., 2004
Brunken, S.; Michael, E.A.; Lewen, F.; Giesen, T.; Ozeki, H.; Winnewisser, G.; Jensen, P.; Herbst, E., High-resolution terahertz spectrum of CH, Can. J. Chem., 2004, 82, 6, 676, https://doi.org/10.1139/v04-034 . [all data]

Brunken, Muller, et al., 2005
Brunken, S.; Muller, H.S.P.; Lewen, F.; Giesen, T.F., Analysis of the rotational spectrum of methylene (CH[sub 2]) in its vibronic ground state with an Euler expansion of the Hamiltonian, J. Chem. Phys., 2005, 123, 16, 164315, https://doi.org/10.1063/1.2074467 . [all data]

Notes

Go To: Top, Gas phase 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
  S°gas,1 bar	Entropy of gas at standard conditions (1 bar)
  ΔfH(+) ion,0K	Enthalpy of formation of positive ion at 0K
  ΔfH°gas	Enthalpy of formation of gas at standard conditions
  ΔrG°	Free energy of reaction at standard conditions
  ΔrH°	Enthalpy of reaction at standard conditions

• Data from NIST Standard Reference Database 69: NIST Chemistry WebBook
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