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تسجيل مستخدم جديدHeteronuclear Limit of Strong-Field Ionization: Fragmentation of HeH$^+$ by Intense Ultrashort Laser Pulses
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The laser-induced fragmentation dynamics of this most fundamental polar molecule HeH$^+$ are measured using an ion beam of helium hydride and an isotopologue at various wavelengths and intensities. In contrast to the prevailing interpretation of strong-field fragmentation, in which stretching of the molecule results primarily from laser-induced electronic excitation, experiment and theory for nonionizing dissociation, single ionization and double ionization both show that the direct vibrational excitation plays the decisive role here. We are able to reconstruct fragmentation pathways and determine the times at which each ionization step occurs as well as the bond length evolution before the electron removal. The dynamics of this extremely asymmetric molecule contrast the well-known symmetric systems leading to a more general picture of strong-field molecular dynamics and facilitating interpolation to systems between the two extreme cases.
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Comment on the PRL paper.
In recent years it became possible to align molecules in free space using ultrashort laser pulses. Here we explore two schemes for controlling molecule-surface scattering process, which are based on the laser-induced molecular alignment. In the first
scheme, a single ultrashort non-resonant laser pulse is applied to a molecular beam hitting the surface. This pulse modifies the angular distribution of the incident molecules, and causes the scattered molecules to rotate with a preferred sense of rotation (clockwise or counter-clockwise). In the second scheme, two properly delayed laser pulses are applied to a molecular beam composed of two chemically close molecular species (isotopes, or nuclear spin isomers). As the result of the double pulse excitation, these species are selectively scattered to different angles after the collision with the surface. These effects may provide new means for the analysis and separation of molecular mixtures.
Proton migration is a ubiquitous process in chemical reactions related to biology, combustion, and catalysis. Thus, the ability to control the movement of nuclei with tailored light, within a hydrocarbon molecule holds promise for far-reaching applic
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