C-C AND C-H BOND SPLITS OF LASER-EXCITED AROMATIC-MOLECULES .3. UV MULTIPHOTON EXCITATION STUDIES

Parent disappearance and fragment formation yields are measured in the UV multiphoton excitation of cycloheptatriene, toluene, and ethylbenzene. The dependence on laser fluence and bath gas pressure is recorded. The results are interpreted in terms of a competition between the absorption of one or two photons, unimolecular reactions, and collisional deactivation of the parent molecules. The yields of the products CH3 and benzyl decrease at high laser fluences, probably because of secondary spontaneous fragmentations of these highly excited primary fragments. © 1990 American Chemical Society.