SPECTROSCOPIC DETECTION AND CHARACTERIZATION OF THE SELENOKETENYL (HCCSe) RADICAL

Abstract

In 1979, Kirshnamachari and $Venkitachalam^{a}$ reported a new transient absorption spectrum observed in the flash photolysis of selenophene. They found a series of strong, sharp bands in the 418-397 nm region and tentatively ascribed them to a $C_{4}H_{4}$ species. We have detected the same band system by laser-induced fluorescence of the products of selenophene in a pulsed discharge jet experiment. Deuterium substitution experiments and the observed selenium isotope splittings show that the carrier of the spectrum contains a hydrogen and a selenium atom. We assign this band system to the previously unknown selenoketenyl or HCCSe radical. The B values for the ground and excited states have been determined by rotational analysis of high resolution spectra of the $0^{0}_{0}$ bands of HCCSe and DCCSe. A combination of LIF and wavelength resolved fluorescence studies are in progress in an attempt to understand the vibronic structure in the spectrum.