Femtosecond pump/probe photoelectron spectroscopy of isolated C_(60)negative ions

摘要

We have measured pump/probe photoelectron spectra of mass-selected,near room temperature C_(60)~-in the gas phase.The lifetime of the vibrationally excited B~-(~2E_g)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 C_(60).This is in contrast to C_(60)for which pumping at the absorption onset (1.95 eV)leads to predominantly intersystem crossing.