Photodissociation of $o-C_6H_4I(CH_2Cl)$ in the near ultraviolet: a case of photoselective C-I bond dissociation

Abstract

We report the photodissociation dynamics of ortho-iodobenzyl chloride $(o-C_6H_4I(CH_2Cl))$ in the ultraviolet. The gas phase dissociation dynamics of o-iodobenzyl chloride at 222, 236, 266, 280, and $\sim304 nm$ was monitored by probing the quantum yields of $I^* \hspace {2mm} (^2P_{1/2})$ as well as $Cl^* \hspace {2mm}(^2P_{1/2})$ production using suitable resonance enhanced multiphoton ionization detection schemes. We find that only iodine atoms in the ground $(I (^2P_{3/2}))$ as well as excited $(I^*)$ states are produced in the dissociation. No $Cl (^2P_{3/2})$ or $Cl^*$ atoms were detected. This accidental bond selective dissociation in o-iodobenzyl chloride is perhaps due to weak coupling among various chromophores present in the molecule and inefficient interchromophore energy transfer among them