Structure in the visible absorption bands of jet-cooled phenylperoxy radicals.

The visible absorption bands of the phenylperoxy radical in the gas phase have been investigated using cavity ring-down spectroscopy. Jet-cooling was used to reduce the spectral congestion. Structured spectra spanning the range from 17,500 to 19,000 cm(-1) are reported for the first time. Analyses of these data have been guided by the results from time-dependent density functional calculations. The observed spectrum was found to be dominated by the bands of the B̃(2)A″-X̃(2)A″ transition. An analysis of the rotational contour for the origin band yielded a homogeneous line width of 2.2 cm(-1), corresponding to a decay rate of 4.1 × 10(11) s(-1). The results provide a rationale for the lack of structure in room temperature spectra that have been previously attributed to phenylperoxy. They also indicate that the lower energy region of the spectrum may show resolvable structure at room temperature. If so, this would provide a more definitive signature for monitoring phenylperoxy in kinetic measurements.

[1]  S. Blanksby,et al.  Isolation and characterization of charge-tagged phenylperoxyl radicals in the gas phase: direct evidence for products and pathways in low temperature benzene oxidation. , 2012, Physical chemistry chemical physics : PCCP.

[2]  Y. Sakamoto,et al.  Pressure dependence of phenylperoxy radical formation in the reaction of phenyl radical with molecular oxygen , 2012 .

[3]  R. Kaiser,et al.  Phenoxy radical (C6H5O) formation under single collision conditions from reaction of the phenyl radical (C6H5, X2A1) with molecular oxygen (O2, X3Σg(-)): the final chapter? , 2011, The journal of physical chemistry. A.

[4]  M. Heaven,et al.  Cavity ring-down spectroscopy of the phenyl radical in a pulsed discharge supersonic jet expansion , 2011 .

[5]  W. Meerts,et al.  High-resolution cavity ringdown spectroscopy of the jet-cooled propyl peroxy radical C(3)H(7)O(2). , 2010, Physical chemistry chemical physics : PCCP.

[6]  H. Davis,et al.  Collision Complex Lifetimes in the Reaction C6H5 + O2 → C6H5O + O , 2010 .

[7]  W. Sander,et al.  Matrix isolation and spectroscopic characterization of the phenylperoxy radical and its rearranged products. , 2009, Chemistry.

[8]  H. Bockhorn,et al.  Thermodynamic properties of the species resulting from the phenyl radical with O2 reaction system , 2008 .

[9]  P. Rupper,et al.  The structure and spectra of organic peroxy radicals. , 2008, Physical chemistry chemical physics : PCCP.

[10]  V. Barone,et al.  Integrated computational approach to vibrationally resolved electronic spectra: anisole as a test case. , 2008, The Journal of chemical physics.

[11]  J. Bozzelli,et al.  Variational analysis of the phenyl + O2 and phenoxy + O reactions. , 2008, The journal of physical chemistry. A.

[12]  R. Kaiser,et al.  Crossed beam reaction of the phenyl radical, (C6H5, X2A′) with molecular oxygen (O2,X3Σg-): Observation of the phenoxy radical, (C6H5O, X2A′) , 2007 .

[13]  T. Miller,et al.  Cavity ringdown spectroscopy of the A˜–X˜ electronic transition of the phenyl peroxy radical , 2006 .

[14]  Alexander M Mebel,et al.  The reaction of phenyl radical with molecular oxygen: a G2M study of the potential energy surface. , 2005, The journal of physical chemistry. A.

[15]  C. Hadad,et al.  Computational Study of the Oxygen Initiated Decomposition of 2-Oxepinoxy Radical: A Key Intermediate in the Oxidation of Benzene , 2004 .

[16]  M. Kawasaki,et al.  Cavity Ring-down Study of the Visible Absorption Spectrum of the Phenyl Radical and Kinetics of Its Reactions with Cl, Br, Cl2, and O2 , 2002 .

[17]  M. Head‐Gordon,et al.  Origin of substituent effects in the absorption spectra of peroxy radicals: time dependent density functional theory calculations. , 2001, Journal of the American Chemical Society.

[18]  R. Osman,et al.  ABSORPTION SPECTRA OF ETHYNYL, ETHENYL, AND PHENYL PEROXYL RADICALS , 1995 .

[19]  Z. Alfassi,et al.  ARYLPEROXYL RADICALS. FORMATION, ABSORPTION SPECTRA, AND REACTIVITY IN AQUEOUS ALCOHOL SOLUTIONS , 1995 .

[20]  A. Mebel,et al.  AB INITIO MOLECULAR ORBITAL CALCULATIONS OF C6H5O2 ISOMERS , 1994 .

[21]  M. C. Lin,et al.  Kinetics of the C6H5 + O2 Reaction at Low Temperatures , 1994 .

[22]  H. Misawa,et al.  A time-resolved EPR study on photodecomposition of dibenzoyl peroxides in carbon tetrachloride , 1989 .

[23]  T. H. Dunning.  Gaussian basis sets for use in correlated molecular calculations. I. The atoms boron through neon and hydrogen , 1989 .