Mapping the evolution of optically generated rotational wave packets in a room-temperature ensemble ofD2

Abstract

A coherent superposition of rotational states in ${\mathrm{D}}_{2}$ has been excited by nonresonant, ultrafast $(12\phantom{\rule{0.3em}{0ex}}\mathrm{fs})$, intense $(2\ifmmode\times\else\texttimes\fi{}{10}^{14}\phantom{\rule{0.3em}{0ex}}\mathrm{W}\phantom{\rule{0.2em}{0ex}}{\mathrm{cm}}^{\ensuremath{-}2})$ $800\phantom{\rule{0.3em}{0ex}}\mathrm{nm}$ laser pulses, leading to impulsive dynamic alignment. Field-free evolution of this rotational wave packet 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, $\ensuremath{\theta}$. The detailed fractional revivals of the neutral ${\mathrm{D}}_{2}$ wave packet as a function of $\ensuremath{\theta}$ and evolution time have been observed and modeled theoretically.