DISSOCIATIVE IONIZATION OF GAS-PHASE CHLOROMETHANES BY INTENSE FIELDSOF PICOSECOND AND ATTOSECOND DURATION

The morphological features are explored of dissociative ionization (DI ) of tetra-, tri-, and di-chloromethane molecules induced by intense e lectric fields of picosecond and attosecond duration. Picosecond-long fields are generated using linearly polarized light pulses (532 nm wav elength, 10(13) W cm(-2) intensity) from a neodymium-doped yttrium alu minum garnet laser whereas attosecond-long fields are obtained by mean s of a fast (similar to 50 MeV) beam of Si3+ ions from a tandem accele rator. The temporal and directional properties of the intense fields t hat the chloromethanes are immersed in influence the DI pattern. For a ll three chloromethanes, the DI patterns measured in light-induced and in ion-induced fields differ from each other, and from those obtained using 70-eV electrons. The ion-impact results are conspicuous by the copious quantities of highly charged fragments and large fluxes of Hions, belying recently expressed expectations that short-duration fiel d-molecule interactions would result in little or no fragmentation. [S 1050-2947(98)00811-7].