Structure Determination in a New Class of Amorphous Cluster Compounds with Extreme Nonlinear Optical Properties

The microscopic structure of two new infrared-driven amorphous white light generators, namely [(PhSn)4S6] and [(CpSn)4S6] and a related amorphous material [(NpSn)4S6], showing 2nd harmonics generation instead, were explored by X-ray and neutron diffraction, EXAFS and Reverse Monte Carlo simulations to explore relations between their extreme nonlinear optical behavior and microscopic structural properties. The current state of research is reported and experimental and simulation results are discussed. The prominent observation is that the molecular units are distorted in the WLG materials which seems not to be the case for the 2nd harmonics generator. Associated is the formation of a net of similarly spaced intra- and intermolecular sulfur atoms which is interpreted as a vibrational network that could explain the high receptivity of the material for infrared radiation. It is also found that the molecules arrange in chains with staggered configuration regarding the arrangement of the organic ligands.