Dynamics of electronic "bubble" formation in solid hydrogen

Excitation of the A(3s sigma) Rydberg state of NO trapped in an H-2 crystal leads to the electronic "bubble" formation around the NO impurity, resulti ng in an increase of 0.9 Angstrom of the ground state cage radius. Its dyna mics has been followed in real-time by femtosecond pump-probe spectroscopy. The results show that "bubble" formation is completed in about 1.5 ps with out recurrences of the cage motion. A model based on classical hydrodynamic s provides quantitative agreement with experimental data, suggesting that s olid hydrogen can be described like a liquid on ultrashort time scales. (C) 1999 Elsevier Science B.V. All rights reserved.