Two-color pump-probe study and internal-energy dependence of Rydberg-state excitation inC60

Abstract

Excitation of Rydberg states in isolated ${\mathrm{C}}_{60}$ is studied by time-resolved photoelectron spectroscopy in a femtosecond two-color pump-probe experiment. The relaxation time for electron-electron interaction is determined to be approximately $100\phantom{\rule{0.3em}{0ex}}\mathrm{fs}$ with the ${t}_{1g}(\mathrm{LUMO}+1)$ orbital being considered to define the doorway state in a nonadiabatic multielectron excitation process. The internal energy stored in vibrational modes of the ${\mathrm{C}}_{60}$ at $770\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ is found to support the excitation process very efficiently while in ``cold'' ${\mathrm{C}}_{60}$ $(80\phantom{\rule{0.3em}{0ex}}\mathrm{K})$, no significant Rydberg population is detected.