Penning-ionization electron spectroscopy of tetrafluoro-TCNQ anion without counter ion prepared on graphite

Abstract Pure anions of tetrafluorotetracyanoquinodimethane ([TFTCNQ] − ) without counter ions were prepared by heating a monolayer film of TFTCNQ deposited on a graphite substrate held at −150°C. During the preparation, the change in the electronic state of the film was monitored by Penning-ionization electron spectroscopy. On the basis of ab initio MO calculations, the first two bands in the Penning spectrum of [TFTCNQ] − were assigned to the ground and lowest triplet states of TFTCNQ arising from the electron emission from [TFTCNQ] − .