Light-Induced Size-Growth of Atomically Precise Nanoclusters

Area of Science:

• * Nanomaterials Science
• * Photochemistry
• * Surface Chemistry

Background:

• * Gold nanoclusters exhibit unique optical and electronic properties dependent on their size and structure.
• * Understanding transformations between different sized nanoclusters is crucial for controlling their properties.

Purpose of the Study:

• * To investigate the photo-induced transformation of the [Au23(S-c-C6)16]−(TOA)+ nanocluster.
• * To elucidate the mechanism of transformation to the Au28(S-c-C6)20 nanocluster.

Main Methods:

• * Time-dependent UV-vis spectroscopy to monitor spectral changes.
• * Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) for size analysis.
• * Electron paramagnetic resonance (EPR) and electrospray ionization mass spectrometry (ESI-MS) for structural and compositional characterization.

Main Results:

• * Photoexcitation of [Au23(S-c-C6)16]−(TOA)+ to [Au23(S-c-C6)16]•−(TOA)+ was observed.
• * Oxidation by O2 led to the formation of an unstable neutral [Au23(S-c-C6)16]0 species.
• * Decomposition and reassembly resulted in the formation of the larger Au28(S-c-C6)20 nanocluster.

Conclusions:

• * A novel photo-induced transformation pathway for gold nanoclusters was demonstrated.
• * The study provides insights into the dynamic nature and size-tunability of gold nanoclusters.
• * This work opens avenues for controlling nanocluster growth and properties through light manipulation.