Direct Observation of the Pressure-Induced Structural Variation in Gold Nanoclusters and the Correlated Optical Response

The ability to gradually modify the atomic structures of nanomaterials and directly identify such structural variation is important in nanoscience research. Here, we present the first example of a high-pressure single-crystal X-ray diffraction analysis of atomically precise metal nanoclusters. The pressure-dependent, subangstrom structural evolution of an ultrasmall gold nanoparticle, Au25S18, has been directly identified. We found that a 0.1 angstrom decrease of the Au-Au bond length could induce a blue-shift of 30 nm in the photoluminescence spectra of gold nanoclusters. From theoretical calculations, the origins of the blue-shift and enhanced photoluminescence under pressure are investigated, which are ascribed to molecular orbital symmetry and conformational locking, respectively. The combination of the high-pressure in situ X-ray results with both theoretical and experimental optical spectra provides a direct and generalizable avenue to unveil the underlying structure-property relations for nanoclusters and nanoparticles which cannot be obtained through traditional physical chemistry measurements.

Automated summary

In this study, the researchers conducted a high-pressure single-crystal X-ray diffraction analysis on atomically precise metal nanoclusters, and directly identified the structural evolution of an ultrasmall gold nanoparticle under pressure. They discovered that a decrease in the Au-Au bond length resulted in a blue-shift in the photoluminescence spectra of the gold nanoclusters. The combination of high-pressure X-ray results, theoretical calculations, and experimental optical spectra provides a direct and generalizable approach to understand the structure-property relations of nanoclusters and nanoparticles.