Structural dynamics in solid hydrogens is impulsively triggered by femtosecond excitation of the lowest Rydberg state of the NO impurity. The resulting charge redistribution induces a local radial deformation of the medium ("bubble" formation) around the impurity. The dynamics of bubble expansion and the ensuing medium response are probed in real-time by pump-probe spectroscopy. The results show that bubble formation is a one-way process without recurrence of the cage motion and is complete in .apprx.1-2 ps. The dynamics in solid hydrogens is modelled by a classical model, which takes into account the emission of sound, friction and surface tension as energy dissipation channels. The first one being the overwhelming channel. For comparison dynamics in solid Ne is also recorded and shows an initial expansion of the matrix cage around the impurity, followed by a low frequency recurrence. The results in solid Ne are complemented by preliminary Mol. Dynamics simulations. [on SciFinder (R)]