Methyl radical

• Formula: CH₃
• Molecular weight: 15.0345
• IUPAC Standard InChI: InChI=1S/CH3/h1H3 Copy

  
• IUPAC Standard InChIKey: WCYWZMWISLQXQU-UHFFFAOYSA-N Copy
• CAS Registry Number: 2229-07-4
• 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:
  • Methyl-d3 radical
  • Methyl-d3 radical
• Permanent link for this species. Use this link for bookmarking this species for future reference.
• Information on this page:
  • Gas phase thermochemistry data
  • Reaction thermochemistry data
  • Vibrational and/or electronic energy levels
  • References
  • Notes
• Other data available:
  • Gas phase ion energetics data
  • Ion clustering data
• Data at other public NIST sites:
  • Electron-Impact Ionization Cross Sections (on physics web site)
  • Gas Phase Kinetics Database
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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 (J/mol*K)
    H° = standard enthalpy (kJ/mol)
    S° = standard entropy (J/mol*K)
    t = temperature (K) / 1000.

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Reaction 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.

Data compiled by: Robert C. Dunbar

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

 +  = ( • )

By formula: Fe⁺ + CH₃ = (Fe⁺ • CH₃)

 +  = ( • )

By formula: Ni⁺ + CH₃ = (Ni⁺ • CH₃)

 +  = ( • )

By formula: Co⁺ + CH₃ = (Co⁺ • CH₃)

( • 2) +  = ( • 3)

By formula: (Si⁺ • 2CH₃) + CH₃ = (Si⁺ • 3CH₃)

( • 3) +  = ( • 4)

By formula: (Si⁺ • 3CH₃) + CH₃ = (Si⁺ • 4CH₃)

( • ) +  = ( • 2)

By formula: (Si⁺ • CH₃) + CH₃ = (Si⁺ • 2CH₃)

 +  = ( • )

By formula: Si⁺ + CH₃ = (Si⁺ • CH₃)

 +  = ( • )

By formula: La⁺ + CH₃ = (La⁺ • CH₃)

 +  = ( • )

By formula: Y⁺ + CH₃ = (Y⁺ • CH₃)

 +  = ( • )

By formula: Lu⁺ + CH₃ = (Lu⁺ • CH₃)

 +  = ( • )

By formula: Cu⁺ + CH₃ = (Cu⁺ • CH₃)

 +  = ( • )

By formula: Cr⁺ + CH₃ = (Cr⁺ • CH₃)

 +  = ( • )

By formula: Mn⁺ + CH₃ = (Mn⁺ • CH₃)

Vibrational and/or electronic energy levels

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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: Marilyn E. Jacox

State:   4f ²E'?

State:   4p ²A₂

State:   3d ²A₁'

State:   3d ²E

State:   3p ²A₂

State:   3s ²A₁'

State:   X

Additional references: Jacox, 1994, page 125; Jacox, 1998, page 214; Jacox, 2003, page 156; Frye, Sears, et al., 1988; Parker, Wang, et al., 1989; Sears, Frye, et al., 1989; Westre and Kelly, 1989; Miller, Burton, et al., 1989; Fawzy, Sears, et al., 1990; Rudolph, Hall, et al., 1996

Notes

References

Go To: Top, Gas phase thermochemistry data, Reaction thermochemistry 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]

Tsang, 1996
Tsang, W., Heats of Formation of Organic Free Radicals by Kinetic Methods in Energetics of Organic Free Radicals, Martinho Simoes, J.A.; Greenberg, A.; Liebman, J.F., eds., Blackie Academic and Professional, London, 1996, 22-58. [all data]

Fisher, Schultz, et al., 1989
Fisher, E.R.; Schultz, r.H.; Armentrout, P.B., Guided Ion Beam Studies of the State - Specific Reactions of Fe+(6D,4F) with CH3X (X = Cl, Br, I), J. Phys. Chem., 1989, 93, 21, 7382, https://doi.org/10.1021/j100358a027 . [all data]

Schultz, Elkind, et al., 1988
Schultz, R.H.; Elkind, J.L.; Armentrout, P.B., Electronic Effects in C-H and C-C Bond Activation: State-Specific Reactions of Fe+(6D,4F) with Methane, Ethane and Propane, J. Am. Chem. Soc., 1988, 110, 2, 411, https://doi.org/10.1021/ja00210a017 . [all data]

Fisher, Sunderlin, et al., 1989
Fisher, E.R.; Sunderlin, L.S.; Armentrout, P.B., Guided Ion Beam Studies of the Reactions of CO+ and Ni+ with CH3X (X=Cl, Br, I). Implications for the Metal-Methyl Ion Bond Energies, J. Phys. Chem., 1989, 93, 21, 7375, https://doi.org/10.1021/j100358a026 . [all data]

Georgiadis, Fisher, et al., 1989
Georgiadis, R.; Fisher, E.R.; Armentrout, P.B., Neutral and Ionic Metal-Hydrogen and Metal-Carbon Bond Energies: Reactions of Co+, Ni+, and Cu+ with Ethane, Propane, Methylpropane, and Dimethylpropane, J. Am. Chem. Soc., 1989, 111, 12, 4251, https://doi.org/10.1021/ja00194a016 . [all data]

Lin, Dunbar, et al., 1996
Lin, C.-Y.; Dunbar, R.C.; Haynes, C.L.; Armentrout, P.B.; Tonner, D.S.; McMahon, T.J., The Dissociation Thermochemistry of Tetramethylsilane Ion. Comparative Determination by Thermal Dissociation and Threshold Collisional Dissociation, J. Phys. Chem., 1996, 100, 50, 19659, https://doi.org/10.1021/jp962523s . [all data]

Sunderlin and Armentrout, 1989
Sunderlin, L.S.; Armentrout, P.B., Periodic Trends in Chemical Reactivity: Reactions of Sc+, Y+, La+, and Lu+ with Methane and Ethane, J. Am. Chem. Soc., 1989, 111, 11, 3845, https://doi.org/10.1021/ja00193a015 . [all data]

Georgiadis and Armentrout, 1989
Georgiadis, R.; Armentrout, P.B., Reactions of Ground State Cr+ with C2H6, C2H4, cyclo-C3H6, and cyclo-C2H4O: Bond Energies for CrCHn+ (n= 1-3), Int. J. Mass Spectrom. Ion Proc., 1989, 89, 2-3, 227, https://doi.org/10.1016/0168-1176(89)83062-9 . [all data]

Georgiadis and Armentrout, 1989, 2
Georgiadis, R.; Armentrout, P.B., Translational and Electronic Energy Dependence of the Reaction of Mn+ with Ethane, Int. J. Mass Spectrom. Ion Proc., 1989, 91, 2, 123, https://doi.org/10.1016/0168-1176(89)83003-4 . [all data]

Hudgens, DiGiuseppe, et al., 1983
Hudgens, J.W.; DiGiuseppe, T.G.; Lin, M.C., Two photon resonance enhanced multiphoton ionization spectroscopy and state assignments of the methyl radical, J. Chem. Phys., 1983, 79, 2, 571, https://doi.org/10.1063/1.445857 . [all data]

Black and Powis, 1988
Black, J.F.; Powis, I., Rotational structure and predissociation dynamics of the methyl 4pz(v=0) Rydberg state investigated by resonance enhanced multiphoton ionization spectroscopy, J. Chem. Phys., 1988, 89, 7, 3986, https://doi.org/10.1063/1.454832 . [all data]

Herzberg and Shoosmith, 1956
Herzberg, G.; Shoosmith, J., Absorption spectrum of free CH₃ and CD₃ radicals, Can. J. Phys., 1956, 34, 523. [all data]

Herzberg, 1961
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]

Milligan and Jacox, 1967
Milligan, D.E.; Jacox, M.E., Infrared and Ultraviolet Spectroscopic Study of the Products of the Vacuum-Ultraviolet Photolysis of Methane in Ar and N2 Matrices. The Infrared Spectrum of the Free Radical CH3, J. Chem. Phys., 1967, 47, 12, 5146, https://doi.org/10.1063/1.1701772 . [all data]

DiGiuseppe, Hudgens, et al., 1982
DiGiuseppe, T.G.; Hudgens, J.W.; Lin, M.C., Multiphoton ionization of methyl radicals in the gas phase, J. Phys. Chem., 1982, 86, 1, 36, https://doi.org/10.1021/j100390a008 . [all data]

Heinze, Heberle, et al., 1994
Heinze, J.; Heberle, N.; Kohse-Hoinghaus, K., The CH3 3pz2A2´´ ← X 2A2´´ 000 band at temperatures up to 1700 K investigated by REMPI spectroscopy, Chem. Phys. Lett., 1994, 223, 4, 305, https://doi.org/10.1016/0009-2614(94)00469-2 . [all data]

Zhang, Zhang, et al., 2005
Zhang, B.; Zhang, J.; Liu, K., Imaging the "missing" bands in the resonance-enhanced multiphoton ionization detection of methyl radical, J. Chem. Phys., 2005, 122, 10, 104310, https://doi.org/10.1063/1.1859277 . [all data]

Fu, Hu, et al., 2005
Fu, H.B.; Hu, Y.J.; Bernstein, E.R., IR/UV double resonant spectroscopy of the methyl radical: Determination of ν[sub 3] in the 3p[sub z] Rydberg state, J. Chem. Phys., 2005, 123, 23, 234307, https://doi.org/10.1063/1.2135772 . [all data]

Callear and Metcalfe, 1976
Callear, A.B.; Metcalfe, M.P., Oscillator strengths of the bands of the B2 A´1---X2 A´´2 system of CD3 and a spectroscopic measurement of the recombination rate comparison with CH3, Chem. Phys., 1976, 14, 2, 275, https://doi.org/10.1016/0301-0104(76)80045-6 . [all data]

Westre, Gansberg, et al., 1992
Westre, S.G.; Gansberg, T.E.; Kelly, P.B.; Ziegler, L.D., Structure and dynamics of higher vibronic levels in the methyl radical Rydberg 3s state, J. Phys. Chem., 1992, 96, 9, 3610, https://doi.org/10.1021/j100188a012 . [all data]

Settersten, Farrow, et al., 2003
Settersten, T.B.; Farrow, R.L.; Gray, J.A., Coherent infrared--ultraviolet double-resonance spectroscopy of CH3, Chem. Phys. Lett., 2003, 370, 1-2, 204, https://doi.org/10.1016/S0009-2614(03)00062-9 . [all data]

Holt, McCurdy, et al., 1984
Holt, P.L.; McCurdy, K.E.; Weisman, R.B.; Adams, J.S.; Engel, P.S., Transient CARS spectroscopy of the ν1 band of methyl radical, J. Chem. Phys., 1984, 81, 7, 3349, https://doi.org/10.1063/1.448000 . [all data]

Kelly and Westre, 1988
Kelly, P.B.; Westre, S.G., Resonance Raman spectroscopy of the methyl radical, Chem. Phys. Lett., 1988, 151, 3, 253, https://doi.org/10.1016/0009-2614(88)85284-9 . [all data]

Triggs, Zahedi, et al., 1992
Triggs, N.E.; Zahedi, M.; Nibler, J.W.; DeBarber, P.; Valentini, J.J., High resolution study of the ν1 vibration of CH3 by coherent Raman photofragment spectroscopy, J. Chem. Phys., 1992, 96, 3, 1822, https://doi.org/10.1063/1.462083 . [all data]

Zahedi, Harrison, et al., 1994
Zahedi, M.; Harrison, J.A.; Nibler, J.W., 266 nm CH3I photodissociation: CH3 spectra and population distributions by coherent Raman spectroscopy, J. Chem. Phys., 1994, 100, 6, 4043, https://doi.org/10.1063/1.466342 . [all data]

Hadrich, Hefter, et al., 1996
Hadrich, S.; Hefter, S.; Pfelzer, B.; Doerk, T.; Jauernik, P.; Uhlenbusch, J., Determination of the absolute Raman cross section of methyl, Chem. Phys. Lett., 1996, 256, 1-2, 83, https://doi.org/10.1016/0009-2614(96)00411-3 . [all data]

Tan, Winer, et al., 1972
Tan, L.Y.; Winer, A.M.; Pimentel, G.C., Infrared Spectrum of Gaseous Methyl Radical by Rapid Scan Spectroscopy, J. Chem. Phys., 1972, 57, 9, 4028, https://doi.org/10.1063/1.1678876 . [all data]

Yamada, Hirota, et al., 1981
Yamada, C.; Hirota, E.; Kawaguchi, K., Diode laser study of the ν2 band of the methyl radical, J. Chem. Phys., 1981, 75, 11, 5256, https://doi.org/10.1063/1.441991 . [all data]

Wormhoudt and McCurdy, 1989
Wormhoudt, J.; McCurdy, K.E., A measurement of the strength of the ν2 band of CH3, Chem. Phys. Lett., 1989, 156, 1, 47, https://doi.org/10.1016/0009-2614(89)87078-2 . [all data]

Stancu, Ropcke, et al., 2005
Stancu, G.D.; Ropcke, J.; Davies, P.B., Line strengths and transition dipole moment of the ν[sub 2] fundamental band of the methyl radical, J. Chem. Phys., 2005, 122, 1, 014306, https://doi.org/10.1063/1.1812755 . [all data]

Snelson, 1970
Snelson, A., Infrared matrix isolation spectrum of the methyl radical produced by pyrolysis of methyl iodide and dimethyl mercury, J. Phys. Chem., 1970, 74, 3, 537, https://doi.org/10.1021/j100698a011 . [all data]

Jacox, 1977
Jacox, M.E., Matrix isolation study of the infrared spectrum and structure of the CH3 free radical, J. Mol. Spectrosc., 1977, 66, 2, 272, https://doi.org/10.1016/0022-2852(77)90217-X . [all data]

Lee and Lee, 2011
Lee, Y.-F.; Lee, Y.-P., Infrared absorption of CH3SO2 observed upon irradiation of a p-H2 matrix containing CH3I and SO2, J. Chem. Phys., 2011, 1334, 12, 124314, https://doi.org/10.1063/1.3567117 . [all data]

Amano, Bernath, et al., 1982
Amano, T.; Bernath, P.F.; Yamada, C.; Endo, Y.; Hirota, E., Difference frequency laser spectroscopy of the ν3 band of the CH3 radical, J. Chem. Phys., 1982, 77, 11, 5284, https://doi.org/10.1063/1.443797 . [all data]

Tanarro, Sanz, et al., 1994
Tanarro, I.; Sanz, M.M.; Bermejo, D.; Domingo, C.; Santos, J., Double modulation-high resolution infrared spectroscopic technique: The ν3 band of the CH3 radical and excited states of CH4 in a hollow cathode discharge, J. Chem. Phys., 1994, 100, 1, 238, https://doi.org/10.1063/1.466991 . [all data]

Tanarro, Sanz, et al., 1994, 2
Tanarro, I.; Sanz, M.M.; Domingo, C.; Bermejo, D.; Santos, J.; Domenech, J.L., Transition dipole moment of the .nu.3 band of CH3, J. Phys. Chem., 1994, 98, 23, 5862, https://doi.org/10.1021/j100074a009 . [all data]

Bethardy and Macdonald, 1995
Bethardy, G.A.; Macdonald, R.G., Direct measurement of the transition dipole moment of the v3 asymmetric C--H stretching vibration of the CH3 radical, J. Chem. Phys., 1995, 103, 8, 2863, https://doi.org/10.1063/1.470499 . [all data]

Davis, Anderson, et al., 1997
Davis, S.; Anderson, D.T.; Duxbury, G.; Nesbitt, D.J., Jet-cooled molecular radicals in slit supersonic discharges: Sub-Doppler infrared studies of methyl radical, J. Chem. Phys., 1997, 107, 15, 5661, https://doi.org/10.1063/1.474259 . [all data]

Scherer, Aniolek, et al., 1997
Scherer, J.J.; Aniolek, K.W.; Cernansky, N.P.; Rakestraw, D.J., Determination of methyl radical concentrations in a methane/air flame by infrared cavity ringdown laser absorption spectroscopy, J. Chem. Phys., 1997, 107, 16, 6196, https://doi.org/10.1063/1.474284 . [all data]

Kawaguchi, 2001
Kawaguchi, K., High-resolution Fourier transform infrared spectra of the CH, Can. J. Phys., 2001, 79, 2-3, 449, https://doi.org/10.1139/p00-093 . [all data]

Pacansky and Bargon, 1975
Pacansky, J.; Bargon, J., Low temperature photochemical studies on acetyl benzoyl peroxide. Observation of methyl and phenyl radicals by matrix isolation infrared spectroscopy, J. Am. Chem. Soc., 1975, 97, 23, 6896, https://doi.org/10.1021/ja00856a066 . [all data]

Momose, Miki, et al., 1995
Momose, T.; Miki, M.; Uchida, M.; Shimizu, T.; Yoshizawa, I.; Shida, T., Infrared spectroscopic studies on photolysis of methyl iodide and its clusters in solid parahydrogen, J. Chem. Phys., 1995, 103, 4, 1400, https://doi.org/10.1063/1.469763 . [all data]

Tam, Macler, et al., 1997
Tam, S.; Macler, M.; Fajardo, M.E., Matrix isolation spectroscopy of laser ablated carbon species in Ne, D[sub 2], and H[sub 2] matrices, J. Chem. Phys., 1997, 106, 22, 8955, https://doi.org/10.1063/1.474028 . [all data]

Hoshina, Fushitani, et al., 2011
Hoshina, H.; Fushitani, M.; Momose, T., Infrared spectroscopy of rovibrational transitions of methyl radicals (CH3, CD3) in solid parahydrogen, J. Mol. Spectrosc., 2011, 268, 1-2, 164, https://doi.org/10.1016/j.jms.2011.04.014 . [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]

Frye, Sears, et al., 1988
Frye, J.M.; Sears, T.J.; Leitner, D., Diode laser spectroscopy of the ν2 band of CD3, J. Chem. Phys., 1988, 88, 9, 5300, https://doi.org/10.1063/1.454588 . [all data]

Parker, Wang, et al., 1989
Parker, D.H.; Wang, Z.W.; Janssen, M.H.M.; Chandler, D.W., Laser ionization spectroscopy of CD3 via the 3pz 2A'2 Rydberg state, J. Chem. Phys., 1989, 90, 1, 60, https://doi.org/10.1063/1.456466 . [all data]

Sears, Frye, et al., 1989
Sears, T.J.; Frye, J.M.; Spirko, V.; Kraemer, W.P., Extended measurements of the ν2 band of CD3 and the determination of the vibrational potential function for methyl, J. Chem. Phys., 1989, 90, 4, 2125, https://doi.org/10.1063/1.456006 . [all data]

Westre and Kelly, 1989
Westre, S.G.; Kelly, P.B., Examination of CD3 vibrational structure by resonance Raman spectroscopy, J. Chem. Phys., 1989, 90, 12, 6977, https://doi.org/10.1063/1.456273 . [all data]

Miller, Burton, et al., 1989
Miller, J.T.; Burton, K.A.; Weisman, R.B.; Wu, W.-X.; Engel, P.S., Cars spectroscopy of gas phase CD3, Chem. Phys. Lett., 1989, 158, 3-4, 179, https://doi.org/10.1016/0009-2614(89)87317-8 . [all data]

Fawzy, Sears, et al., 1990
Fawzy, W.M.; Sears, T.J.; Davies, P.B., Infrared diode laser spectroscopy of the ν3 fundamental of the CD3 radical, J. Chem. Phys., 1990, 92, 12, 7021, https://doi.org/10.1063/1.458242 . [all data]

Rudolph, Hall, et al., 1996
Rudolph, R.N.; Hall, G.E.; Sears, T.J., Measurement of the ν3 fundamental transition moment and vibrational relaxation rates of the CD3 radical, J. Chem. Phys., 1996, 105, 18, 7889, https://doi.org/10.1063/1.472704 . [all data]

Notes

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

• Symbols used in this document:
  

  S°gas,1 bar	Entropy of gas at standard conditions (1 bar)
  ΔfH°gas	Enthalpy of formation of gas at standard conditions
  ΔrH°	Enthalpy of reaction at standard conditions

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