Anomalous phonon relaxation in Au<sub>333</sub>(SR)<sub>79</sub> nanoparticles with nascent plasmons.
basic_science · Level V
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- Record sourced from PubMed, PMID 31209027.
- Also identified by DOI 10.1073/pnas.1904337116 and PMC identifier 6613166.
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Abstract
Research on plasmons of gold nanoparticles has gained broad interest in nanoscience. However, ultrasmall sizes near the metal-to-nonmetal transition regime have not been explored until recently due to major synthetic difficulties. Herein, intriguing electron dynamics in this size regime is observed in atomically precise Au<sub>333</sub>(SR)<sub>79</sub> nanoparticles. Femtosecond transient-absorption spectroscopy reveals an unprecedented relaxation process of 4-5 ps-a fast phonon-phonon relaxation process, together with electron-phonon coupling (∼1 ps) and normal phonon-phonon coupling (>100 ps) processes. Three types of -R capped Au<sub>333</sub>(SR)<sub>79</sub> all exhibit two plasmon-bleaching signals independent of the -R group as well as solvent, indicating plasmon splitting and quantum effect in the ultrasmall core of Au<sub>333</sub>(SR)<sub>79</sub> This work is expected to stimulate future work on the transition-size regime of nanometals and discovery of behavior of nascent plasmons.