Controlling a Molecule’s Fate

Abstract

We experimentally investigate the dependence of the fragmentation behavior of the ethylene dication on the intensity and duration of the laser pulses that initiate the fragmentation dynamics by strong-field double ionization. Using coincidence momentum imaging for the detection of ionic fragments, we disentangle the different contributions of ionization from lower-valence orbitals and field-driven excitation dynamics to the population of certain dissociative excited ionic states that are connected to one of several possible fragmentation pathways towards a given set of fragment ions. We find that the excitation probability to a particular excited state and therewith the outcome of the fragmentation reaction strongly depend on the parameters of the laser pulse. This, in turn, opens up new possibilities for controlling the outcome of fragmentation reactions of polyatomic molecules in that it may allow one to selectively enhance or suppress individual fragmentation channels, which was not possible in previous attempts of controlling fragmentation processes of polyatomic molecules with strong laser fields.

Light-Induced Ultrafast Molecular Dynamics: From Photochemistry to Optochemistry

“…(b) When a laser pulse removes electrons from a HOMO electron (yellow) and a HOMO–1 electron (blue), the molecule tends to break into an H + ion and a C 2 H 3 + ion. Figure adapted with permission from ref ( 57 ). Copyright 2014 American Physical Society.…”

“…In this case, one can use a tailored laser pulse to selectively break a particular chemical bond, thus leading to designated chemical products. An example is the control of the breakup of the C 2 H 4 molecules as intuitively shown in Figure , − where removal of the HOMO and HOMO–2 electrons leads to a decomposition into two CH 2 + ions while a removal of the HOMO and HOMO–1 electrons results in an H + ion and a C 2 H 3 + ion. The excitation probability to a certain excited state and the outcome of the reaction pathway could be well controlled by finely tuning the parameter of the applied laser pulses.…”