Photodissociation dynamics of propionyl chloride in the ultraviolet region

Journal Article · Wed Jan 07 04:00:00 EST 2009 · Journal of Chemical Physics

DOI:https://doi.org/10.1063/1.3012353· OSTI ID:21254979

Zhengrong, Wei; Bing, Zhang ^[1]; Xiaopeng, Zhang; Weibin, Lee; Lin, K -C ^[2]

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1. State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071 (China)
2. Department of Chemistry, National Taiwan University, Taipei 106, Taiwan (China)

Velocity imaging technique combined with (2+1) resonance-enhanced multiphoton ionization (REMPI) is used to detect primary photodissociation of propionyl chloride. In one-color experiments at 235 nm, the Cl and Cl* fragments are produced rapidly, leading to a fraction of translational energy release of 0.37 and 0.35, anisotropy parameters of 1.1 and 0.8, and quantum yield of 0.67 and 0.33, respectively, when initial excitation of the {sup 1}(n, {pi}*){sub CO} band is coupled to the {sup 1}(n{sub Cl}, {sigma}{sub C-Cl}*) repulsive configuration. The resulting propionyl radical with sufficient internal energy may undergo secondary dissociation to yield CO that is characteristic of an isotropic distribution. The REMPI spectra of the CO (0,0) and (1,1) bands are measured, giving rise to a Boltzmann rotational temperature of 1200 and 770 K, respectively, and a Boltzmann vibrational temperature of 2800 K. A minor channel of HCl elimination is not detected, probably because of predissociation in two-photon absorption at 235 nm. In two-color experiments comprising an additional 248 nm photolyzing laser, Cl and Cl* are produced with a fraction of translational energy release of 0.43 and 0.40 and anisotropy parameters of 1.0 and 0.6, respectively. The secondary production of CO is not observed although the internal energy partitioned in the propionyl radical is in the proximity of the dissociation barrier. In either experimental scheme, a small component appearing in the center of the Cl and Cl* images is proposed to stem from ground state dissociation via internal conversion.

• OSTI ID: 21254979
• Journal Information: Journal of Chemical Physics, Journal Name: Journal of Chemical Physics Journal Issue: 1 Vol. 130; ISSN JCPSA6; ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
ABSORPTION
ANISOTROPY
CHLORINATED ALIPHATIC HYDROCARBONS
CHLORINE IONS
EXCITATION
GROUND STATES
HYDROCHLORIC ACID
INTERNAL CONVERSION
MULTI-PHOTON PROCESSES
PHOTOIONIZATION
PHOTOLYSIS
PHOTON-MOLECULE COLLISIONS
PHOTONS
PREDISSOCIATION
RADICALS
TEMPERATURE RANGE 0400-1000 K
TEMPERATURE RANGE 1000-4000 K
ULTRAVIOLET RADIATION