Ultrafast structural dynamics in electronically excited solid neon. I. Real-time probing of the electronic bubble formation

The dynamics of electron bubble formation upon excitation of the A(3ss) Rydberg orbital of NO in solid Ne was studied by conventional spectroscopy and fs pump-probe spectroscopy. The fs pump pulse initiates the formation of a bubble by the expansion of the Ne atoms surrounding the NO impurity, generating a wave packet of intermol. NO-matrix modes. The dynamics exhibits a 1st peak due to the sampling of the initial expansion of the bubble followed by >=1 oscillation of the bubble boundaries, which occurs .apprx.1.3 ps after the start of the dynamics and is significantly broader than the 1st peak. The whole process of bubble formation and stabilization is over by 2-3 ps in which 0.54 eV are released into the lattice. This suggests a sudden, probably shock-wave-like, emission of energy into the lattice. In a 1st approxn. the time dependence of the bubble radius was directly extd. from the pump-probe transients. This trajectory is used to simulate the exptl. data with agreement. Paradoxically, even though solid Ne is a lighter solid, the overall dynamics (expansion and recurrence) are slower than for the heavier Ar solid. [on SciFinder (R)]