Photodissociation of Partially Fluorinated Alkyl Iodides in Their A-Band

Abstract

Photodissociation dynamics of partially substituted alkyl iodides with fluorine atoms at β and γ positions has been investigated. The iodine atoms in the ground I(2P3/2) and spin−orbit excited I*(2P1/2) states produced in the ultraviolet photolysis of CF3CH2I, C6F13CH2CH2I, and C8F17CH2CH2I have been detected using a two photon laser induced fluorescence (TPLIF) scheme. The I* quantum yield of the above iodides at 222, 236, 266, 280, and ∼305 nm corresponding to the red and blue wings as well as the peak of their A-band absorption spectrum has been determined. The I* yield from β and γ-substituted iodides is found to remain more or less unchanged as a function of excitation wavelength below 262 nm, which is the peak of their A-band. The observed dynamics at 222, 236, and 266 nm can be adequately described by the known Landau−Zener curve crossing model between the 3Q0 and 1Q1 states. However, at wavelengths above 262 nm, the measured I* quantum yield of β and γ-substituted alkyl iodides reflects that the 3...