Role of broadband-laser-pulse temporal extent in H2+photodissociation

Abstract

Molecular hydrogen ion (H 2 + ) dissociation paths of bond softening (BS) and above threshold dissociation (ATD) are investigated exploiting few-cycle chirped laser pulses. 7-fs laser pulses are temporally broadened in a controlled way by the imposed positive chirp covering the range 7-55 fs. The dissociation of the H 2 + molecules via the BS and ATD paths is then systematically monitored as a function of the pulses duration in conditions of equal H 2 + yield. The experimental data show distinctive characteristics both in the energy dissociation spectral structure as well as in the yield as the pulse duration broadens. The interpretation of our experimental findings is supported by ab initio calculations based on the H 2 + dissociation time-dependent Schrödinger equation (TDSE) in a strong laser field, thus shedding light into the details of the underlying dissociation dynamics involving few-cycle pulses. The results are also analyzed within the Floquet picture discussing certain limits of its applicability. Finally, our experimental findings show strong molecular alignment for durations longer than 20 fs.

3D Coincidence Imaging Disentangles Intense Field Double Detachment of SF6–

“…Accordingly, the rescattering mechanism is extremely sensitive to laser polarization accounting for the acute suppression of HHG by polarization ellipticity. − This intuitive description of intense field interaction with atoms and molecules opened new pathways for using the HHG process itself as a spectroscopic tool and for probing light matter interaction on the attosecond time scale. − Furthermore, on the basis of the rescattering model, bichromatic counter-rotating circularly polarized laser pulses were specially designed and implemented to produce circularly polarized HHG pulses . So far, the majority of experimental and theoretical efforts to understand the interaction of intense laser pulses with matter were performed on overall neutral atomic and molecular systems. − ,− Significant efforts were invested also in studies of cationic systems that are inherently important for describing mechanisms involving early ionization of the neutral species by the intense laser pulse. − Intense field interactions with anions are intrinsically different from both neutral and cationic systems. The typically low electron detachment energies of anions make it possible to realize extreme conditions of very rapid detachment at relatively low laser intensities.…”

Steering the electron in dissociatingH2+via manipulating two-state population dynamics by a weak low-frequency field

“…Due to the dipole selection rules, however, the pathways on the states of opposite parities always involve unequal net absorption numbers of photons. For example, in the dissociation of H2+ the 2«-photon (n > 0) absorption leads to the ls a g state but only the (2n + l)-photon absorption contributes to the 2pau state, resulting in staggered peaks of the nuclear kinetic energy distributions of two pathways [15,24], Therefore, in order to enhance the electron localization, the overlap in the energy distributions of dissociation pathways of opposite parities should be increased by the external field [25].…”

Influence of laser intensities on the dissociation of hydrogen molecular ions

“…In this paper, we systematically study laser intensity effects on the dissociation of H + 2 [34][35][36][37][38][39]. Depending on laser intensities and photon energies, H + 2 may dissociate along selected electronic potential curves, and the dissociative fragments gain different kinetic energies.…”