Nonlinear UV excitation: Neutral vs ionic channels of molecular fragmentation

Publisher Website
Google Scholar
Abstract
Following multiphoton or nonlinear UV excitation (22 ps, 266 nm, ∼2.5 mJ) of simple molecules at low pressure, we have measured the temporal evolution of emissive product populations with subnanosecond time resolution. For several parents, our data support the importance, beneath the I. P., of fragmentation to yield neutral species competitive with further excitation to yield parent ions. The primary neutrals and ions are subject to further excitation. Channels of dissociation are recognized as prompt (unimolecular) and delayed (ion–molecule) components of fragment emission. Representative data for CH2CO are presented. A discussion of some recent REMPI results on this molecule is also given. The question has arisen whether rapid production of neutrals, energetically requiring nhν>I.P. of the parent, occurs through superexcited species. We suggest that a conclusive demonstration of such pathways has yet to be achieved.
Keywords

This publication has 20 references indexed in Scilit: