Cl*(2P1/2) production dynamics from chloroiodomethane (CH2ICl) in the ultraviolet

Dynamics of Cl*(P-2(1/2)) production from chloroiodomethane dissociation has been investigated in the near ultraviolet (222 less than or equal to lambda(ex) < 304 nm). The quantum yield of Cl*(P-2(1/2)) production, phi*(Cl), has been measured by monitoring nascent Cl(P-2(3/2)) and Cl* concentrations and compared with the quantum yield of I*(P-2(1/2)) production at the same excitation wavelengths. In the near ultraviolet where most of the transition strength is carried by the sigma*(C-I)<--n(I) transition, the measured Cl* quantum yield decreases as a function of increasing photolysis wavelength. An interchromophore energy transfer mechanism between the C-I and C-Cl chromophores has been proposed to rationalize CI production since the direct excitation of the sigma*(C-CI)<--n(Cl) transition is less likely at wavelengths similar to100 nm away from the peak of the C-Cl absorption band. (C) 2004 Elsevier B.V. All rights reserved.