Photochemistry of adsorbed phenyl iodide: Desorption and photofragmentation dynamics

The photodissociation and photodesorption dynamics of iodobenzene adsorbed at 150 K on LiF substrates has been investigated at 222 nm using the time-of-flight/resonance-enhanced multiphoton ionization/mass spectrometry technique. The Maxwell-Boltzmann (MB) translational temperatures (T_B) calculated for the phenyl radical, atomic iodine in the I (²P _3/2) and (²P_1/2) states, and biphenyl were 1200, 1500, and 1050 K, respectively. The desorbed parent molecule (detected by electron ionization) was found to be translationally colder, with T _B≈900 K. Analysis of translational energy distributions indicate that the adsorption-dissociation mechanism of iodobenzene differs significantly from that of the methyl halides.