Identification and characterization of polyselenides and their radical ions

摘要

Polyselenides, Se_n~(-2) (n chemical bounds 2-4), are frequently encountered at the interface of many solid transition metal selenides in optical, energy conversion and photocataly tic applications. Yet they are poorly characterized. We synthesized several Se_n~(-2) in aqueous solutions by oxidation of HSe~- with H_2O_2. Absortpion and Raman spectra were recorded and the observed bands were assigned to the various species and their vibrational modes. Single-electron reduction and oxidation products were generated in solution by reaction with e_(eq)~- and OH radicals respectively, using the pulse radiolysis technique. Spectra of these radical ions, as well as their formation and decay dynamics were recorded. Ab inition electonic structure and vibrational mode calulations were conducted and the results were compared with the experimental observations.