title: Photodissociation dynamics of pyridine.
abstract: Photodissociation of pyridine, 2,6-d2-pyridine, and d5-pyridine at 193 and 248 nm was investigated separately using multimass ion imaging techniques. Six dissociation channels were observed at 193 nm, including C5NH5 --> C5NH4 + H (10%) and five ring opening dissociation channels, C5NH5 --> C4H4 + HCN, C5NH5 --> C3H3 + C2NH2, C5NH5 --> C2H4 +C3NH, C5NH5 --> C4NH2 + CH3 (14%), and C5NH5 --> C2H2 + C3NH3. Extensive H and D atom exchanges of 2,6-d2-pyridine prior to dissociation were observed. Photofragment translational energy distributions and dissociation rates indicate that dissociation occurs in the ground electronic state after internal conversion. The dissociation rate of pyridine excited by 248-nm photons was too slow to be measured, and the upper limit of the dissociation rate was estimated to be 2x10(3) s(-1). Comparisons with potential energies obtained from ab initio calculations and dissociation rates obtained from the Rice-Ramsperger-Kassel-Marcus theory have been made.
authors.affiliation: Institute of Atomic and Molecular Sciences, Academia Sinica, P.O. Box 23-166, Taipei, Taiwan.
authors.forename: Ming-Fu
authors.initials: MF
authors.lastname: Lin
authors.forename: Yuri A
authors.initials: YA
authors.lastname: Dyakov
authors.forename: Chien-Ming
authors.initials: CM
authors.lastname: Tseng
authors.forename: Alexander M
authors.initials: AM
authors.lastname: Mebel
authors.forename: Sheng Hsien
authors.initials: SH
authors.lastname: Lin
authors.forename: Yuan T
authors.initials: YT
authors.lastname: Lee
authors.forename: Chi-Kung
authors.initials: CK
authors.lastname: Ni