Bond breaking in light-induced potentials

Abstract

We study the photodissociation of ICl(-) under moderately strong (TW/cm(2)) and short (below picosecond) laser pulses. Using a single resonant pump pulse, the photodissociation spectra shows two barely overlapping bands corresponding to Frank-Condon excitation and dissociation in two electronic states. By adding a nonresonant stronger control pulse we show that (1) the photodissociation bands can be blueshifted and (2) the asymptotic state of the fragments depends on the chosen pulse sequence. If the pump pulse precedes the control pulse or the control pulse straddles the pump pulse, the outgoing wave packet has components in the two dissociation channels, whereas if the control pulse precedes the pump pulse, the photodissociation proceeds selectively in a single channel.

A Stark Future for Quantum Control

“…The technical details are outlined above, but for a more detailed discussion of the relation between the two approaches, the reader is directed toward the review by Shore 139 and some of the recent publications by Solá and co-workers. [140][141][142][143] As highlighted previously, there are, in general, a large number of competing high-order, nonlinear effects that may all potentially contribute to the overall system dynamics in the presence of an intense laser field (>10 13 W/cm 2 ). In molecular systems in particular, the theory describing these individual effects is not always well-quantified, and therefore, the challenge of modeling a system where all of these processes are contributing to some degree in modifying the dynamics is often insurmountable.…”

Strong laser field control of fragment spatial distributions from a photodissociation reaction

“…The essential tool in these schemes is a control laser pulse that is precisely defined in terms of spectrum, time, intensity and polarization. A significant number of theoretical proposals and experimental demonstrations of laser control have been presented 3–6 showing laser-induced modifications of observables like the absorption spectrum 7–10 , lifetimes 9, 11–13 , quantum yields 14–16 or even spatial localization of molecules in space 17 .…”

Molecular events in the light of strong fields: A light‐induced potential scenario

“…[117] If several dissociation channels are present, one can use a pump pulse in combination with a strong nonresonant pulse to separate the different channels. [106] However, the field also couples the different excited states so that the dissociation occurs on a "mixed" channel, that is, on a superposition of excited electronic states correlating to different channels. [106,109] In this section, we review some proposals that we have presented to achieve control over different reaction observables, such as the yield and the kinetic energy distribution of the fragments, [109] by using strong nonresonant pulses.…”

“…[106] However, the field also couples the different excited states so that the dissociation occurs on a "mixed" channel, that is, on a superposition of excited electronic states correlating to different channels. [106,109] In this section, we review some proposals that we have presented to achieve control over different reaction observables, such as the yield and the kinetic energy distribution of the fragments, [109] by using strong nonresonant pulses. In the chosen examples, the LIPs are formed between two dissociative potentials that never cross.…”

“…[30] However, most works have been done to create the LIAC or LICI in order to control the output of a photochemical process. In particular, there have been several theoretical proposals to control the yield of a photodissociation reaction, [106] as well as the branching ratio over possible fragmentation channels [35,[106][107][108]121] and the kinetic energy distribution of the fragments. [109] Although most proposals remain experimentally untested, owing to the difficulty of finding good molecular systems where the strong field interaction is strong enough to generate LIPs, yet not too strong that the ionization is predominant, recent experiments have shown that indeed such control is possible.…”