Bound excited electronic states of anions studied by electron photodetachment spectroscopy

Abstract
Excited electronic states of the radical anion of 7,7,8,8- tetracyanoquinodimethane (TCNQDN) which are stable with respect to electron loss have been observed by electron photodetachment spectroscopy. An onset for photodetachment is seen at 1.2 eV, considerably below the known binding energy (2.8 eV). We propose a sequential two-photon detachment process, supported by intensity dependence studies. TCNQDN is representative of a general class of anions which we believe will have such bound states.