Field-free molecular alignment probed by the free electron laser in Hamburg (FLASH)

TL;DR

This study demonstrates field-free molecular alignment using a free electron laser, enabling time-resolved imaging of molecular dynamics and dissociation processes with potential for advanced molecular insights.

Contribution

First experimental demonstration of field-free molecular alignment at a free electron laser, combining ultrashort XUV pulses with rotationally cold molecules for molecular frame studies.

Findings

Rapid changes in ionic fragment distributions reveal rotational dynamics.

Hints of non-linear dissociation dependence on XUV intensity.

Potential for ultrashort XUV pulse experiments in molecular frame.

Abstract

We report experiments on field-free molecular alignment performed at FLASH, the free electron laser (FEL) in Hamburg. The impulsive alignment induced by a 100 fs near-infrared laser pulse in a rotationally cold CO_2 sample is characterized by ionizing and dissociating the molecules with a time delayed extreme ultra-violet (XUV) FEL pulse. The time-dependent angular distributions of ionic fragments measured by a velocity map imaging spectrometer shows rapid changes associated with the induced rotational dynamics. The experimental results also show hints of a dissociation process that depends non-linearly on the XUV intensity. With samples of aligned molecules at FLASH, experiments using ultrashort XUV pulses become possible in the molecular frame, which will enable new insights into the understanding of molecules and their interactions.