Contrasting mechanisms for photodissociation of methyl halides adsorbed on thin films of C6H6 and C6F6

The mechanisms for photodissociation of methyl halides (CH$_3$X, X= Cl, Br, I) have been studied these molecules when adsorbed on thin films C$_6$H$_6$ or C$_6$F$_6$ copper single crystals, using time-of-flight spectroscopy with 248nm and 193nm light. For CH$_3$Cl CH$_3$Br monolayers C$_6$H$_6$, two pathways can be identified: neutral similar to the gas-phase, a dissociative electron attachment (DEA) pathway due photoelectrons from metal. same film display only photodissociation, DEA entirely absent intermolecular quenching via LUMO-derived electronic band in film. CH$_3$I film, illumination light results CH$_3$ photofragments departing A-band absorption. When are illuminated at wavelength, additional new observed that absorption molecular energy transfer leading dissociation top. proposed mechanism this is charge-transfer complex layer CH$_3$I.