Impulsive laser-induced alignment of OCS molecules at FERMI

TL;DR

This paper reports the successful impulsive alignment of OCS molecules using femtosecond laser pulses at FERMI, enabling advanced coherent control experiments with synchronized optical and XUV lasers.

Contribution

First demonstration of impulsive molecular alignment at FERMI using femtosecond pulses and ionization-based probing, linking experimental results with theoretical models.

Findings

Confirmed rotational dynamics match theoretical predictions.

Demonstrated Coulomb explosion imaging of aligned molecules.

Enabled future experiments in molecular control with FERMI's setup.

Abstract

We demonstrate the experimental realization of impulsive alignment of carbonyl sulfide (OCS) molecules at the Low Density Matter Beamline (LDM) at the free-electron laser FERMI. OCS molecules in a molecular beam were impulsively aligned using 200 fs pulses from a near-infrared laser. The alignment was probed through time-delayed ionization above the sulphur 2p edge, resulting in multiple ionization via Auger decay and subsequent Coulomb explosion of the molecules. The ionic fragments were collected using a time-of-flight mass spectrometer and the analysis of ion-ion covariance maps confirmed the correlation between fragments after Coulomb explosion. The analysis of the CO+ and S+ channels allowed us to extract the rotational dynamics, which is in agreement with our theoretical description as well as with previous experiments. This result opens the way for a new class of experiments at LDM within the field of coherent control of molecules with the possibilities that a precisely synchronized optical-pump XUV-probe laser setup like FERMI can offer.