Hydroperoxy radical

• Formula: HO₂
• Molecular weight: 33.0067
• IUPAC Standard InChI: InChI=1S/HO2/c1-2/h1H Copy

  
• IUPAC Standard InChIKey: OUUQCZGPVNCOIJ-UHFFFAOYSA-N Copy
• CAS Registry Number: 3170-83-0
• 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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• Information on this page:
  • Gas phase thermochemistry data
  • Reaction thermochemistry data
  • Vibrational and/or electronic energy levels
  • References
  • Notes
• Other data available:
  • Henry's Law data
  • Gas phase ion energetics data
• Data at other public NIST sites:
  • Microwave spectra (on physics lab web site)
  • 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: 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

 +  =

By formula: O₂^- + H⁺ = HO₂

Vibrational and/or electronic energy levels

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

State:   B

State:   A

State:   X

Additional references: Jacox, 1994, page 49; Jacox, 1998, page 153; Jacox, 2003, page 43; Radford, Evenson, et al., 1974; Hougen, 1975; Hougen, Radford, et al., 1975; Beers and Howard, 1975; Beers and Howard, 1976; Saito, 1977; Tuckett, Freedman, et al., 1979, 2; McKellar, 1979; Barnes, Brown, et al., 1980; Charo and De Lucia, 1982; Saito, Endo, et al., 1983; Lubic, Amano, et al., 1984; Uehara, Kawaguchi, et al., 1985; Sears, Takacs, et al., 1986; Chance, Park, et al., 1995; Chance, Ramsay, et al., 2001; Fink and Ramsay, 2002; DeSain, Ho, et al., 2003; Wang and Andrews, 2005; Fink and Ramsay, 2006

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]

Travers, Cowles, et al., 1989
Travers, M.J.; Cowles, D.C.; Ellison, G.B., Reinvestigation of the Electron Affinities of O2 and NO, Chem. Phys. Lett., 1989, 164, 5, 449, https://doi.org/10.1016/0009-2614(89)85237-6 . [all data]

Troe, 1969
Troe, J., Ber. Bunsenges. Phys. Chem., 1969, 73, 946. [all data]

Kijewski and Troe, 1971
Kijewski, H.; Troe, J., Study of the pyrolysis of H2O2 in the presence of H2and CO by use of UV absorption of HO2, Int. J. Chem. Kinet., 1971, 3, 3, 223, https://doi.org/10.1002/kin.550030304 . [all data]

Paukert and Johnston, 1972
Paukert, T.T.; Johnston, H.S., Spectra and Kinetics of the Hydroperoxyl Free Radical in the Gas Phase, J. Chem. Phys., 1972, 56, 6, 2824, https://doi.org/10.1063/1.1677613 . [all data]

Hochanadel, Ghormley, et al., 1972
Hochanadel, C.J.; Ghormley, J.A.; Ogren, P.J., Absorption Spectrum and Reaction Kinetics of the HO2 Radical in the Gas Phase, J. Chem. Phys., 1972, 56, 9, 4426, https://doi.org/10.1063/1.1677885 . [all data]

Crowley, Simon, et al., 1991
Crowley, J.N.; Simon, F.G.; Burrows, J.P.; Moortgat, G.K.; Jenkin, M.E.; Cox, R.A., The HO2 radical UV absorption spectrum measured by molecular modulation, UV/diode-array spectroscopy, J. Photochem. Photobiol. A: Chem., 1991, 60, 1, 1, https://doi.org/10.1016/1010-6030(91)90001-A . [all data]

Hunziker and Wendt, 1974
Hunziker, H.E.; Wendt, H.R., Near infrared absorption spectrum of HO2, J. Chem. Phys., 1974, 60, 11, 4622, https://doi.org/10.1063/1.1680949 . [all data]

Becker, Fink, et al., 1974
Becker, K.H.; Fink, E.H.; Langen, P.; Schurath, U., Near infrared emission bands of the HO2 radical, J. Chem. Phys., 1974, 60, 11, 4623, https://doi.org/10.1063/1.1680950 . [all data]

Hunziker and Wendt, 1976
Hunziker, H.E.; Wendt, H.R., Electronic absorption spectra of organic peroxyl radicals in the near infrared, J. Chem. Phys., 1976, 64, 8, 3488, https://doi.org/10.1063/1.432606 . [all data]

Freedman and Jones, 1976
Freedman, P.A.; Jones, W.J., J. Chem. Soc., 1976, Faraday Trans. 2 72, 207. [all data]

Becker, Fink, et al., 1978
Becker, K.H.; Fink, E.H.; Leiss, A.; Schurath, U., A study of the near infrared emission bands of the hydroperoxyl radical at medium resolution, Chem. Phys. Lett., 1978, 54, 1, 191, https://doi.org/10.1016/0009-2614(78)85694-2 . [all data]

Tuckett, Freedman, et al., 1979
Tuckett, R.P.; Freedman, P.A.; Jones, W.J., The emission bands of HO, Mol. Phys., 1979, 37, 2, 379, https://doi.org/10.1080/00268977900100331 . [all data]

Fink, Kruse, et al.
Fink, E.H.; Kruse, H.; Ramsay, D.A., Paper WF2, 42nd Symposium on Molecular Spectroscopy, Columbus, Ohio, June 1987.. [all data]

Fink and Ramsay, 1997
Fink, E.H.; Ramsay, D.A., High-Resolution Study of theÃ2A´ → X2A´´ Transition of HO2: Analysis of the 000--000 Band, J. Mol. Spectrosc., 1997, 185, 2, 304, https://doi.org/10.1006/jmsp.1997.7401 . [all data]

Ramond, Blanksby, et al., 2002
Ramond, R.M.; Blanksby, S.J.; Kato, S.; Bierbaum, V.M.; Davico, G.E.; Schwartz, R.L.; Lineberger, W.C.; Ellison, G.B., Heat of Formation of the Hydroperoxyl Radical HOO Via Negative Ion Studies, J. Phys. Chem. A, 2002, 106, 42, 9641, https://doi.org/10.1021/jp014614h . [all data]

Holstein, Fink, et al., 1983
Holstein, K.J.; Fink, E.H.; Zabel, F., The ν3 vibration of electronically excited HO2(A2A´), J. Mol. Spectrosc., 1983, 99, 1, 231, https://doi.org/10.1016/0022-2852(83)90307-7 . [all data]

Yamada, Endo, et al., 1983
Yamada, C.; Endo, Y.; Hirota, E., Difference frequency laser spectroscopy of the ν1 band of the HO2 radical, J. Chem. Phys., 1983, 78, 7, 4379, https://doi.org/10.1063/1.445321 . [all data]

Thompson and Jacox, 1989
Thompson, W.E.; Jacox, M.E., The vibrational spectra of molecular ions isolated in solid neon. II. O+4 and O-4, J. Chem. Phys., 1989, 91, 7, 3826, https://doi.org/10.1063/1.456868 . [all data]

Jacox and Thompson
Jacox, M.E.; Thompson, W.E., J. Phys. Chem. A 117. [all data]

Milligan and Jacox, 1963
Milligan, D.E.; Jacox, M.E., Infrared Spectroscopic Evidence for the Species HO2, J. Chem. Phys., 1963, 38, 11, 2627, https://doi.org/10.1063/1.1733562 . [all data]

Jacox and Milligan, 1972
Jacox, M.E.; Milligan, D.E., Spectrum and structure of the HO2 free radical, J. Mol. Spectrosc., 1972, 42, 3, 495, https://doi.org/10.1016/0022-2852(72)90225-1 . [all data]

Smith and Andrews, 1974
Smith, D.W.; Andrews, L., Argon matrix infrared spectra and vibrational analysis of the hydroperoxyl and deuteroperoxyl free radicals, J. Chem. Phys., 1974, 60, 1, 81, https://doi.org/10.1063/1.1680809 . [all data]

Bandow and Akimoto, 1985
Bandow, H.; Akimoto, H., Photochemistry of ketene in oxygen/argon matrixes and in solid oxygen at 11 K, J. Phys. Chem., 1985, 89, 5, 845, https://doi.org/10.1021/j100251a026 . [all data]

Nagai, Endo, et al., 1981
Nagai, K.; Endo, Y.; Hirota, E., Diode laser spectroscopy of the HO2 ν2 band, J. Mol. Spectrosc., 1981, 89, 2, 520, https://doi.org/10.1016/0022-2852(81)90044-8 . [all data]

Burkholder, Hammer, et al., 1992
Burkholder, J.B.; Hammer, P.D.; Howard, C.J.; Towle, J.P.; Brown, J.M., Fourier transform spectroscopy of the ν2 and ν3 bands of HO2, J. Mol. Spectrosc., 1992, 151, 2, 493, https://doi.org/10.1016/0022-2852(92)90582-9 . [all data]

Johns, McKellar, et al., 1978
Johns, J.W.C.; McKellar, A.R.W.; Riggin, M., Laser magnetic resonance spectroscopy of the ν3 fundamental band of HO2 at 9.1 μm, J. Chem. Phys., 1978, 68, 9, 3957, https://doi.org/10.1063/1.436308 . [all data]

Buchanan, Thrush, et al., 1983
Buchanan, J.W.; Thrush, B.A.; Tyndall, G.S., The absolute intensity of the ν3 band of HO2, Chem. Phys. Lett., 1983, 103, 2, 167, https://doi.org/10.1016/0009-2614(83)87487-9 . [all data]

Zahniser and Stanton, 1984
Zahniser, M.S.; Stanton, A.C., A measurement of the vibrational band strength for the ν3 band of the HO2 radical, J. Chem. Phys., 1984, 80, 10, 4951, https://doi.org/10.1063/1.446517 . [all data]

Nelson and Zahniser, 1991
Nelson, D.D., Jr.; Zahniser, M.S., Diode laser spectroscopy of the ν3 vibration of the HO2 radical, J. Mol. Spectrosc., 1991, 150, 2, 527, https://doi.org/10.1016/0022-2852(91)90247-8 . [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]

Radford, Evenson, et al., 1974
Radford, H.E.; Evenson, K.M.; Howard, C.J., HO2 detected by laser magnetic resonance, J. Chem. Phys., 1974, 60, 8, 3178, https://doi.org/10.1063/1.1681503 . [all data]

Hougen, 1975
Hougen, J.T., The assignment of molecular infrared spectra from a laser magnetic resonance spectrometer, J. Mol. Spectrosc., 1975, 54, 3, 447, https://doi.org/10.1016/0022-2852(75)90172-1 . [all data]

Hougen, Radford, et al., 1975
Hougen, J.T.; Radford, H.E.; Evenson, K.M.; Howard, C.J., Analysis of the laser magnetic resonance spectrum of HO2, J. Mol. Spectrosc., 1975, 56, 2, 210, https://doi.org/10.1016/0022-2852(75)90236-2 . [all data]

Beers and Howard, 1975
Beers, Y.; Howard, C.J., The microwave spectrum of HO2 near 65 GHz, J. Chem. Phys., 1975, 63, 10, 4212, https://doi.org/10.1063/1.431191 . [all data]

Beers and Howard, 1976
Beers, Y.; Howard, C.J., The spectrum of DO2 near 60 GHz and the structure of the hydroperoxyl radical, J. Chem. Phys., 1976, 64, 4, 1541, https://doi.org/10.1063/1.432375 . [all data]

Saito, 1977
Saito, S., Microwave spectrum of the HO2 radical, J. Mol. Spectrosc., 1977, 65, 2, 229, https://doi.org/10.1016/0022-2852(77)90190-4 . [all data]

Tuckett, Freedman, et al., 1979, 2
Tuckett, R.P.; Freedman, P.A.; Jones, W.J., The near infra-red emission band of DO, Mol. Phys., 1979, 37, 2, 403, https://doi.org/10.1080/00268977900100341 . [all data]

McKellar, 1979
McKellar, A.R.W., Laser magnetic resonance spectroscopy of the ν2 fundamental band of DO2 at 9.8 μm, J. Chem. Phys., 1979, 71, 1, 81, https://doi.org/10.1063/1.438060 . [all data]

Barnes, Brown, et al., 1980
Barnes, C.E.; Brown, J.M.; Radford, H.E., The EPR and LMR spectra of the DO2 radical: Determination of ground-state parameters, J. Mol. Spectrosc., 1980, 84, 1, 179, https://doi.org/10.1016/0022-2852(80)90252-0 . [all data]

Charo and De Lucia, 1982
Charo, A.; De Lucia, F.C., The millimeter and submillimeter spectrum of HO2: The effects of unpaired electronic spin in a light asymmetric rotor, J. Mol. Spectrosc., 1982, 94, 2, 426, https://doi.org/10.1016/0022-2852(82)90018-2 . [all data]

Saito, Endo, et al., 1983
Saito, S.; Endo, Y.; Hirota, E., The microwave spectrum of the DO2 radical, J. Mol. Spectrosc., 1983, 98, 1, 183, https://doi.org/10.1016/0022-2852(83)90208-4 . [all data]

Lubic, Amano, et al., 1984
Lubic, K.G.; Amano, T.; Uehara, H.; Kawaguchi, K.; Hirota, E., The ν1 band of the DO2 radical by difference frequency laser and diode laser spectroscopy: The equilibrium structure of the hydroperoxyl radical, J. Chem. Phys., 1984, 81, 11, 4826, https://doi.org/10.1063/1.447508 . [all data]

Uehara, Kawaguchi, et al., 1985
Uehara, H.; Kawaguchi, K.; Hirota, E., Diode laser spectroscopy of the ν3 and ν2 fundamental bands of DO2, J. Chem. Phys., 1985, 83, 11, 5479, https://doi.org/10.1063/1.449668 . [all data]

Sears, Takacs, et al., 1986
Sears, T.J.; Takacs, G.A.; Howard, C.J.; Crownover, R.L.; Helminger, P.; De Lucia, F.C., Rotational spectroscopy of DO2 by FIR LMR and millimeter-wave absorption, J. Mol. Spectrosc., 1986, 118, 1, 103, https://doi.org/10.1016/0022-2852(86)90228-6 . [all data]

Chance, Park, et al., 1995
Chance, K.V.; Park, K.; Evenson, K.M.; Zink, L.R.; Stroh, F., Far-Infrared Spectrum of HO2, J. Mol. Spectrosc., 1995, 172, 2, 407, https://doi.org/10.1006/jmsp.1995.1188 . [all data]

Chance, Ramsay, et al., 2001
Chance, K.V.; Ramsay, D.A.; Fink, E.H., Improved Molecular Constants for the Ground State of DO2, J. Mol. Spectrosc., 2001, 207, 1, 123, https://doi.org/10.1006/jmsp.2001.8310 . [all data]

Fink and Ramsay, 2002
Fink, E.H.; Ramsay, D.A., High-Resolution Study of the Atilde;2A´→X2A´´ Transition of DO2: Analysis of the 000--000 Band, J. Mol. Spectrosc., 2002, 216, 2, 322, https://doi.org/10.1006/jmsp.2002.8621 . [all data]

DeSain, Ho, et al., 2003
DeSain, J.D.; Ho, A.D.; Taatjes, C.A., High-resolution diode laser absorption spectroscopy of the O--H stretch overtone band (2,0,0)←(0,0,0) of the HO2 radical, J. Mol. Spectrosc., 2003, 219, 1, 163, https://doi.org/10.1016/S0022-2852(03)00022-5 . [all data]

Wang and Andrews, 2005
Wang, X.; Andrews, L., Infrared Spectrum of Hg(OH), Inorg. Chem., 2005, 44, 1, 108, https://doi.org/10.1021/ic048673w . [all data]

Fink and Ramsay, 2006
Fink, E.H.; Ramsay, D.A., Analysis of perturbations in the state of HO2, J. Mol. Struct., 2006, 795, 1-3, 155, https://doi.org/10.1016/j.molstruc.2005.11.045 . [all data]

Notes

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• 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
  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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