Magnetic resonance study of arsenic bonding sites in ternary chalcogenide glasses

75As NQR and high-field NMR experiments have been performed on GexAsySe1−x−y glasses. Evolution of As bonding structure from arsenic sites with axially symmetric distribution of the electric field gradient (EFG) to highly asymmetric As surroundings has been revealed. Arsenic atoms form pyramidal structural units in Ge2As2Se7 with no evidence of significant concentration of homopolar bonds. In Ge2As2Se5 most of arsenic atoms form structural units with two As–As bonds per atom and asymmetric EFG distribution. Arsenic bondings become more complicated in Ge0.33As0.12Se0.55 where all arsenic sites are highly distorted. The combination of NQR and NMR data provide valuable information on arsenic bonding dynamics in these glasses.