Competition between hydrogen elimination and deprotonation in CD_n⁺ fragmentation by intense ultrashort laser pulses*

We investigated hydrogen elimination (CD_n⁺ ® CD_n-1⁺ + D) and deprotonation (CD_n⁺ ® CD_n-1 + D⁺) processes in CD_n⁺ fragmentation by focusing intense ultrashort laser pulses^‡ onto fast (keV) CD_n⁺ ion beam targets. The laser induced fragments, including neutral fragments, are measured in coincidence, and their 3-dimentional momenta are evaluated. One of the main goals of this study is to determine the relative importance of hydrogen elimination versus deprotonation. We also compare the kinetic energy release (KER) and angular distributions of these fragmentation processes. Curiously, following the ionization of CD₃⁺ and in addition to the expected deprotonation (CD₃²⁺ ® CD₂⁺ + D⁺), hydrogen elimination (CD₃²⁺ ® CD₂²⁺ + D) was also observed, though far less frequently.

^‡780-nm, 25-fs, about 10¹⁵-W/cm² laser pulses at 10 kHz