Lattice response of quantum solids to an impulsive local perturbation

The lattice response of solid para-H2 to an impulsive electronic excitation was studied using femtosecond pump-probe spectroscopy. The evolution of an electronic bubble in the crystal, created upon excitation of the A(3ssigma) Rydberg state of an NO impurity, was followed in real time, with a resolution of 100 fs. The experimental results, interpreted in connection with molecular dynamics simulations with quantum corrections, indicate the presence of three stages in the dynamics: a sub-100 fs "adiabatic" phase, a 0.5-1 ps phase, corresponding to the interaction of the first with the next shells driven by the bubble expansion, and a 5 ps phase, corresponding to a slow rearrangement of the environment surrounding the impurity. These findings indicate that the lattice response in solid para-H2 resembles that of a liquid.