Analyzing laser-induced alignment of weakly-bound molecular aggregates

TL;DR

This study investigates the laser-induced alignment of a weakly-bound molecular cluster, demonstrating that a rigid rotor approximation is valid under typical experimental conditions and exploring the limits of this approximation.

Contribution

The paper provides a theoretical analysis of the rotational and torsional dynamics of the indole(H2O) cluster, highlighting the validity of the rigid rotor approximation and its parameter boundaries.

Findings

Coupling between internal and overall rotations is small.

Rigid rotor approximation is valid for typical experimental field strengths.

Boundaries of the approximation's validity are identified.

Abstract

The rotational and torsional dynamics of the prototypical floppy $\text{indole}(\text{H}_2\text{O})$ molecular cluster was theoretically and computationally analyzed. The time-dependent Schr\"odinger equation was solved for a reduced-dimensionality description of the cluster, taking into account overall rotations and the internal rotation of the water moiety. Based on our results, it became clear that coupling between the internal and the overall rotations are small, and that for typical field strengths in alignment and mixed-field orientation experiments the rigid rotor approximation can be employed to describe the investigated dynamics. Furthermore, the parameter space over which this is valid and its boundaries where the coupling of the internal and overall rotation can no longer be neglected were explored.