Mapping the Evolution of Optically-Generated Rotational Wavepackets in a Room Temperature Ensemble of D$_2$

TL;DR

This study investigates the evolution of rotational wavepackets in D$_2$ molecules at room temperature using ultrafast laser pulses, mapping their dynamics with high temporal resolution and theoretical modeling.

Contribution

It presents the first detailed experimental and theoretical analysis of fractional revivals of rotational wavepackets in D$_2$ at room temperature.

Findings

Observation of fractional revivals as a function of angle and time

High temporal resolution mapping of wavepacket evolution

Theoretical modeling matches experimental data

Abstract

A coherent superposition of rotational states in D$_2$ has been excited by nonresonant ultrafast (12 femtosecond) intense (2 $\times$ 10$^{14}$ Wcm$^{-2}$) 800 nm laser pulses leading to impulsive dynamic alignment. Field-free evolution of this rotational wavepacket has been mapped to high temporal resolution by a time-delayed pulse, initiating rapid double ionization, which is highly sensitive to the angle of orientation of the molecular axis with respect to the polarization direction, $\theta$. The detailed fractional revivals of the neutral D$_2$ wavepacket as a function of $\theta$ and evolution time have been observed and modelled theoretically.