Gold nanoclusters (AuNCs) with diameter less than 2 nanometres have fluorescent properties. These nanoclusters can be prepared by microwave assisted synthesis using BSA (bovine serum albumin) as a template (1). During the synthesis, Au(III) ions are reduced to Au(I) or Au(0) which are bonded to BSA forming thus Au(I)-BSA complexes and/or AuNCs-BSA, respectively. Here, femtosecond stimulated Raman spectroscopy (FSRS), an ultrafast nonlinear optical technique is used to study vibrational structure of Au(I)-BSA complexes and AuNCs-BSA. FSRS has time resolution comparable to the vibrational period of molecular movements (ps to fs) and energy resolution less than 10 cm^-1. Three laser pulses are exploited in a typical FSRS experiment: actinic pulse, Raman pulse and probe pulse (2). According to our preliminary results, FSRS represents a very promising tool in the investigation of Au(I)-BSA complexes and AuNCs-BSA systems.

This research was funded by Grant Agency of the Czech Republic, grant number 19-03207S.

References:

(1) P. Andrýsková et al., The effect of fatty acids and BSA purity on synthesis and properties of fluorescent gold nanoclusters. Nanomaterials 2020, 10, 343; doi:10.3390/nano10020343

(2) Kukura P. et al. Femtosecond Stimulated Raman Spectroscopy. Annu. Rev. Phys. Chem. 2007. 58:461–88