Femtosecond pump/probe photoelectron spectroscopy of isolated C60 negative ions

Abstract

We have measured pump/probe photoelectron spectra of mass-selected, near room temperature C60- in the gas phase. The lifetime of the vibrationally excited B- (2Eg) state at a calculated energy of 1.26 eV was found to be tau = 2.2+/-0.2 ps. The dominant decay process corresponds to intramolecular radiationless transitions into ground state C60-. This is in contrast to C60 for which pumping at the absorption onset (1.95 eV) leads to predominantly intersystem crossing.