Femtosecond Photofragment Spectroscopy: The Reaction ICN → CN + I.

In this Letter we report our first results on femtosecond photofragment spectroscopy. The reaction studied is I-CN → [I···CN] → I + CN. A photolysis-and-probe scheme is used to measure the rate of the primary photodissociation of ICN under collisionless conditions. The CN buildup time is measured from these preliminary results to be 600 • 100 fs. These direct measurements for the time of bond breakage in ICN are discussed in relation to the dynamics of the recoil process of the reaction.