title: Dynamics of OH formation in the photodissociation of o-nitrobenzoic acid at 295 and 355 nm.
abstract: Photodissociation dynamics of o-nitrobenzoic acid at 295 and 355 nm is studied by probing the nascent OH photoproduct employing the single-photon laser-induced fluorescence technique. At both of the photolysis wavelengths, the OH fragments are found to be vibrationally cold but have different rotational state distributions. Upon photolysis at 295 nm, the relative population of OH in different rotational states does not follow the Boltzmann equilibrium distribution, whereas upon photolysis at 355 nm, a Boltzmann distribution is observed with a rotational temperature of 1010 +/- 100 K. Between the two spin-orbit states, (2)Pi(3/2) and (2)Pi(1/2), the former is found to be preferentially populated, and the distribution of the Pi(A') state for the Lambda-doublet is dominant at both of the wavelengths studied. Several possible dissociation pathways of o-nitrobenzoic acid leading to formation of the OH fragment are investigated computationally. On the basis of the theoretical and experimental studies, a possible mechanism of OH formation from the photodissociation of o-nitrobenzoic acid at 295 and 355 nm is proposed.
authors.affiliation: State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China.
authors.forename: Can-Hua
authors.initials: CH
authors.lastname: Zhou
authors.forename: Shi-Bo
authors.initials: SB
authors.lastname: Cheng
authors.forename: Ju-Long
authors.initials: JL
authors.lastname: Sun
authors.forename: Hong-Ming
authors.initials: HM
authors.lastname: Yin
authors.forename: Ke-Li
authors.initials: KL
authors.lastname: Han
authors.forename: Guo-Zhong
authors.initials: GZ
authors.lastname: He
mesh_terms: D003198:Computer Simulation; D017665:Hydroxyl Radical / Q000737:chemistry*; D008956:Models, Chemical; D009579:Nitrobenzoates / Q000737:chemistry*; D010777:Photochemistry; D010782:Photolysis; D011789:Quantum Theory; D012399:Rotation; D014732:Vibration
chemical_list: C518437:2-nitrobenzoate; D009579:Nitrobenzoates; D017665:Hydroxyl Radical