Photo-Ionization and Electron-Capture Processes in Solution: The Flash Photolysis of Ether Solutions of Potassium Metal and of Naphthacene Dianion

Abstract

Flash excitation of solutions of potassium in tetrahydrofuran or dimethoxyethane leads to a new substance with a broad infrared absorption. This transforms rapidly to a second intermediate, which finally returns to the original state by a slow first-order process (k = 12.8 sec—1). These changes are interpreted as photodissociation of doubly trapped electrons (e2) followed by fast recombination to a triplet state of e2 and slower return of the triplet to the original singlet. Flashing solutions of naphthacene dianion yields the monoanion and near-infrared bands attributable to e1. The recombination process is second-order (k = 1.5×109 moles—1 sec—1). Much faster electron capture by neutral naphthacene is also observed.