Local Cluster Distortions in Amorphous Organotin Sulfide Compounds and Their Influence on the Nonlinear Optical Properties

摘要

The local structure of four amorphous organotin sulfide compounds isinvestigated by X-ray absorption spectroscopy. These compounds exhibit anonlinear optical (NLO) response upon irradiation with a continuous-wavenear-infrared laser. Their basic structural motif is a hetero-adamantanecluster with different organic substituent, but depending on the morphologyof the compound and the choice of the organic substituent, the nature ofthe NLO response changes to either a second harmonic generation or thegeneration of a supercontinuum, potentially appearing as white light. Thestructural results provide an experimental evidence that the nature of theNLO properties is tied to distortions occurring at the cluster core, withalmost ideal clusters in compounds that show second harmonic generation,and strongly distorted clusters in the case of compounds that generatea supercontinuum. These distortions may enable a closer proximity of thecluster cores, altering the intermolecular order, and thereby influencing theNLO response.