Real-time measurements of ultrafast electronic dynamics in the disproportionation of [TCNQ](2-)(2) using a visible sub-10 fs pulse laser

Abstract

The reduction of 7,7,8,8-tetracyanoquinodimethane (TCNQ) generates a pi radical anion, TCNQ(center dot-), that dimerizes in methanol solution. This dimer ([TCNQ](2-)(2)) exhibits a charge-transfer absorption peak at 620 nm and will disproportionate to give TCNQ and TCNQ(2-) in response to excitation within this charge transfer band. The present study examined the electronic dynamics of [TCNQ](2-)(2) disproportionation. The disproportionation was found to proceed in two steps. Electron transfer, representing the first step, occurred within the 10 fs pulse window, followed by the actual dissociation, within 350 fs. The emission lifetime of the singlet excited state of TCNQ(2-) was estimated to be 900 fs. (C) 2016 Elsevier B.V. All rights reserved.