Knowledge Bank

Measurements have been made of the lifetimes of various vibrational levels of the lowest excited electronic state of the cyclopentadienyl. $C5H5$. and methylcyclopentadienyl, $C5H4CH3$, radicals. These measurements show a similar decrease in lifetime for each radical as the energy of the vibrational level is increased. These observations are consistent with a significant non-radiative decay route opening in the excited state.