title: UV photodissociation of the van der Waals dimer (CH3I)2 revisited: pathways giving rise to ionic features.
abstract: The CH(3)I A-state-assisted photofragmentation of the (CH(3)I)(2) van der Waals dimer at 248 nm and nearby wavelengths has been revisited experimentally using the time-of-flight mass spectrometry with supersonic and effusive molecular beams and the "velocity map imaging" technique. The processes underlying the appearance of two main (CH(3)I)(2) cluster-specific features in the mass spectra, namely, I(2)(+) and translationally "hot" I(+) ions, have been studied. Translationally hot I(+) ions with an average kinetic energy of 0.94+/-0.02 eV appear in the one-quantum photodissociation of vibrationally excited I(2)(+)((2)Pi(32,g)) ions (E(vib)=0.45+/-0.11 eV) via a "parallel" photodissociation process with an anisotropy parameter beta=1.55+/-0.03. Comparison of the images of I(+) arising from the photoexcitation of CH(3)I clusters versus those from neutral I(2) shows that "concerted" photodissociation of the ionized (CH(3)I)(2)(+) dimer appears to be the most likely mechanism for the formation of molecular iodine ion I(2)(+), instead of photoionization of neutral molecular iodine.
authors.affiliation: Institute of Chemical Kinetics and Combustion, Institutskaja Street 3, Novosibirsk 630090, Russia.
authors.forename: Konstantin V
authors.initials: KV
authors.lastname: Vidma
authors.forename: Alexey V
authors.initials: AV
authors.lastname: Baklanov
authors.forename: Evgeny B
authors.initials: EB
authors.lastname: Khvorostov
authors.forename: Valerii N
authors.initials: VN
authors.lastname: Ishchenko
authors.forename: Sergei A
authors.initials: SA
authors.lastname: Kochubei
authors.forename: André T J B
authors.initials: AT
authors.lastname: Eppink
authors.forename: Dmitri A
authors.initials: DA
authors.lastname: Chestakov
authors.forename: David H
authors.initials: DH
authors.lastname: Parker