The evolution from the metallic (or plasmonic) to molecular state in metal nanoparticles constitutes a central question in nanoscience research because of its importance in understanding the origin of metallic bonding and offering fundamental insights into the birth of surface plasmon resonance. We utilize the atomically precise gold nanoclusters protected by thiolate ranging in size from 1 nm to 3.5 nm (including Au25, Au38, Au144, Au246, Au333, Au~520, Au~940) and investigate the grand transition from metallic to molecular state by femtosecond transient absorption spectroscopy, as well as the impact of the transition on catalytic reactions. By probing the electron-phonon coupling of the gold nanoclusters, we have mapped out that the transition occurs between 2.3 nm (Au333) and 1.7 nm (Au144). Recently, we have further identified that Au246 nanoclusters (2.2 nm) are still non-metallic based on the analysis of the electron and phonon dynamics. Future work on the photophysics of these gold nanoclusters will further help to benefit their applications in energy storage and conversion.

Evolution from the plasmon to exciton state in atomically precise gold nanoparticles

254th National Meeting (2017)

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