Elucidating isotopic effects in intense ultrafast laser-driven D₂H⁺fragmentation

Abstract

The triatomic hydrogen molecular ion is instrumental as a benchmark towards understanding the strong-field dynamics of polyatomic molecules. Using a crossed-beams coincidence three-dimensional momentum imaging method, we demonstrate clear isotopic effects in the fragmentation of D2H+ induced by 7 fs (40 fs), 790 nm laser pulses at an intensity of 1016 W cm−2 (5 × 1015 W cm−2). Our experiment uniquely separates all fragmentation channels and provides kinematically complete information for the nuclear fragments. For example, we show that for dissociative ionization of D2H+ there is a large difference in branching ratios of the two-body channels, namely, H++D dominates D++HD+, whereas there is minimal difference in branching ratios between the dissociation channels H++D2 and D++HD.

Duration of an intense laser pulse can determine the breakage of multiple chemical bonds

“…Our experiments thus show that a suitable choice of the laser pulse duration can determine the ratio of molecules within an ensemble of identical neutral ethylene molecules that fragment into two or three moieties, respectively. In contrast, in the abovementioned experiments 18 the preponderance towards fragmentation into a certain channel is introduced by the different dynamics of different isotopic variants when exposed to shorter or longer pulses. However, data taken for two pulse durations indicate a sensitivity of the relative yields of two-body and three-body fragmentation channels of on the pulse length 17 , although this observation was not further investigated.…”

“…As the laser-driven fragmentation of a polyatomic molecule is dictated by the relative dynamics of the nuclei and the electrons, as well as the coupling between these two dynamical systems, the duration of the driving laser pulse is a crucial parameter. This point has been investigated, e.g., by experiments 16 17 18 and simulations 19 20 using the simplest polyatomic molecules, / and isotopic variants, as model systems. It has been shown that due to the different nuclear dynamics, isotopic variants exhibit different dependence of the branching ratio of certain channels on the pulse duration 18 .…”

Importance of one- and two-photon transitions in the strong-field dissociation of NO2+

“…Three-dimensional (3D) momentum imaging technology [31][32][33][34][35][36], however, has proven invaluable in navigating this complexity. The rich information provided by these techniques [37][38][39][40][41] has been fruitfully employed to determine pathways important for dynamics [17,[42][43][44][45][46][47][48]. For example, momentum imaging has facilitated the extensive study of the laser-induced dissociation pathways of O 2 + [49 -52].…”

Carrier-envelope phase control of electron motion in laser-driven H32+

“…On the experimental side it is known that H 3 + can be ejected as a result of a laser pulse interacting with a polyatomic hydrocarbon molecule [72,73]. Measurements where a laser pulse is aimed directly at H 3 + were initiated in the last few years [44][45][46][74][75][76].…”