RESUMO
We investigate the two- and three-body fragmentation of tribromomethane (bromoform, CHBr3) resulting from multiple ionization by 28-femtosecond near-infrared laser pulses with a peak intensity of 6 × 1014 W cm-2. The analysis focuses on channels consisting exclusively of ionic fragments, which are measured by coincidence momentum imaging. The dominant two-body fragmentation channel is found to be Br+ + CHBr2+. Weaker HBr+ + CBr2+, CHBr+ + Br2+, CHBr2+ + Br2+, and Br+ + CHBr22+ channels, some of which require bond rearrangement prior to or during the fragmentation, are also observed. The dominant three-body fragmentation channel is found to be Br+ + Br+ + CHBr+. This channel includes both concerted and sequential fragmentation pathways, which we identify using the native frames analysis method. We compare the measured kinetic energy release and momentum correlations with the results of classical Coulomb explosion simulations and discuss the possible isomerization of CHBr3 to BrCHBr-Br (iso-CHBr3) prior to the fragmentation.
RESUMO
The Coulomb explosion of tribromomethane (bromoform, CHBr3) induced by 28 fs near-infrared laser pulses is investigated by three-dimensional coincidence ion momentum imaging. We focus on the fragmentation into three, four, and five ionic fragments measured in coincidence and present different ways of visualizing the three-dimensional momentum correlations. We show that the experimentally observed momentum correlations for 4- and 5-fold coincidences are well reproduced by classical Coulomb explosion simulations and contain information about the structure of the parent molecule that could be used to differentiate structural isomers formed, for example, in a pump-probe experiment. Our results thus provide a clear path toward visualizing structural dynamics in polyatomic molecules by strong-field-induced Coulomb explosion imaging.
