Charakterisierung elektronischer Relaxationsprozesse in freien Fulleren-Anionen
Final Report Abstract
Temperature controlled free C60 anions have been studied by normal and timeresolved photoelectron spectroscopy. Four main results have been obtained: 1) The VDE of the clusters exhibit a strong increase with increasing temperature, which has been traced back to a softening of vibrational modes in the anion. 2) After excitation in a broad photon energy range an autodetachment process occurs, which results in photoelectrons with kinetic energies independent of the photon energy. This autodetaching state must be a doubly excited state, and has an excitation energy of about 3.4 eV. 3) The lifetime of the t1g state decreases strongly with temperature; the low temperature asymptotic value is 7.7 ps. The origin of this fast nonradiative decay is not clear. 4) The identical temporal behaviour of the t1g and the AD peaks in the photoelectron spectra indicate that the autodetaching state might be formed by two electrons excited to the t1g state. These results demonstrate that C60 is indeed a very interesting system for the study of fast electron dynamics. Despite the new findings many questions remain open, which will be tackled in future experiments on C60 and other fullerenes.
