Optical absorption of isolated selenium chains under pressure

Abstract

In order to study the effect of the intrachain interaction on the electronic structure of Se chains, isolated Se chains confined in mordenite channels (M‐Se) were uniaxially compressed using smaller molecules than the diameter of the mordenite (M) channels as a pressure transmitting medium. Optical transmission spectra of M‐Se were measured up to 10 GPa using a diamond anvil cell. The absorption edge of M‐Se shifts to lower energy with increasing pressure. The pressure coefficient of optical gap of M‐Se is −0.03eV/GPa, which is about one fifth of that of bulk trigonal Se. A simple tight‐binding calculation suggest that the gap narrowing is attributable to the increase of a second neighbor lone‐pair to lone‐pair interaction.