Relationship between ESR (Electron Spin Resonance) and Photodarkening in Glassy As2S3

摘要

Ever since the discovery of optically-induced paramagnetism in the chalcogenide glasses there have been attempts to correlate optically-induced electron spin resonance (ESR) with various metastable optical effects. One of the most universal and most prominent optical effects is the so-called photodarkening (PD) processs which occurs in essentially all chalcogenide glasses. The PD effect is a shift of the optical absorption edge to lower energies after irradiation with light of energies near that of the optical band gap. The PD effect has also been observed in some oxide glasses such as As203, but the presence of a group VI element appears to be necessary since no PD is observed in such materials as amorphous arsenic (a-As) or amorphous silicon (a-Si). Keywords: Electron spin resonance, Photodarkening, Chalcogenide glasses, Arsenic sulfides.