Carrier-envelope phase dependence of the directional fragmentation and hydrogen migration in toluene in few-cycle laser fields

Abstract

The dissociative ionization of toluene initiated by a few-cycle laser pulse as a function of the carrier envelope phase (CEP) is investigated using single-shot velocity map imaging. Several ionic fragments, CH3+, H2+, and H3+, originating from multiply charged toluene ions present a CEP-dependent directional emission. The formation of H2+ and H3+ involves breaking C-H bonds and forming new bonds between the hydrogen atoms within the transient structure of the multiply charged precursor. We observe appreciable intensity-dependent CEP-offsets. The experimental data are interpreted with a mechanism that involves laser-induced coupling of vibrational states, which has been found to play a role in the CEP-control of molecular processes in hydrocarbon molecules, and appears to be of general importance for such complex molecules.

Selective bond breaking of CO2 in phase-locked two-color intense laser fields: laser field intensity dependence

“…However, quantum interference may not be the dominant mechanism of the selective bond breaking of CO 2 because many excited states could be involved in the dissociation process. 39 Indeed, unlike D 2 + , 27 the asymmetry parameter shows no clear dependence on the total kinetic energy E kin in the field intensity range investigated in the present study (not shown, see Fig. 4…”

Phase- and intensity-dependence of ultrafast dynamics in hydrocarbon molecules in few-cycle laser fields

“…Moreover, it has been demonstrated that controlling the CEP permits selective breaking of either C-H bond, leading to directional proton emission [32,33]. Very recently, we have reported on the control of the preferential direction of hydrogen migration in acetylene and allene [34], and toluene [35] using the CEP of a few-cycle laser pulse. Here, we go beyond studies at a single intensity of the laser field and report on combined CEP and intensity studies of the strong-field-induced dissociative ionization of acetylene and allene.…”

“…[30][31][32][33][34][35]). CEP effects in the deprotonation of acetylene, induced by few-cycle laser pulses, have attracted considerable interest.…”

Sub-cycle steering of the deprotonation of acetylene by intense few-cycle mid-infrared laser fields

“…Controlling molecular structure rearrangements using ultrashort laser fields has attracted enormous interest for the last decades [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17]. Chemical transformations can be controlled with various laser parameters, including intensity, pulse duration, chirp, and the electric field waveform.…”

“…The control of reactions occurring in hydrocarbon molecules is interesting from both a fundamental and an application point of view. The processes that may be steered with tailored fields include C-H and C-C bond breaking and proton migration reactions [4,6,[13][14][15][16]. A prototype system is acetylene, where it was demonstrated that both the directionality of the deprotonation [6,14] and proton migration [13] can be steered with the CEP of few-cycle pulses in the visible to near-infrared (NIR) region.…”