Nonadiabatic multielectron dynamics in (moderaterately) strong laser fields: C60 a model case for large finite system

Abstract

This chapter presents evidence for the influence of multi-electron dynamics in ultrafast fragmentation and ionization dynamics in C60. Fragmentation initiated by 50 femtosecond (fs) pulses is substantially enhanced if the ionizing pulse is preceded by a strong pump pulse. After excitation of several electrons, the energy deposited into the electronic system is redistributed among many degrees of freedom. For large fragments, the fragmentation process occurs on a time scale of nanoseconds to microseconds in the ionic system. In contrast, small fragments are created on a femto- and picosecond time scale, most probably by dissociative processes in the neutral system and subsequentionization. Using still shorter pulses of 9 fs, energy absorbed by the electronic system is redistributed within sub 100 fs among the electronic system, and no evidence for electron–phonon coupling is observed at intensities of about 7 × 1013 W/cm2. Further experimental and theoretical efforts are needed to fully understand the complex charge and energy deposition and redistribution process in large finite systems in strong laser fields.