Nanooptics and photonics
The complex studies on gold- captopril nanoclusters
Waszkielewicz M.1, Olesiak – Bańska J.1, Matczyszyn K.1, Samoć M.1
1 Advanced Materials Engineering and Modelling Group, Faculty of Chemistry, Wroclaw University of Science and Technology, Wyb. Wyspianskiego 27, 50-370 Wroclaw, Poland. 
E-mail: magdalena.waszkielewicz@pwr.edu.pl

Gold nanoclusters (AuNCs) are ultrasmall particles with core sizes smaller than 2 nm, which place them between single metal atoms and larger nanoparticles. They exhibit unique physicochemical properties such as well-defined molecular structure, discrete electronic transitions and quantized charging [1]. In recent years, nonlinear optical properties of gold nanoclusters have attracted increasing attention and some results on quantitative evaluation of NLO properties at selected wavelengths have been published [2], although there is still a big gap in more complex studies in this field.
The aim of this work was a comprehensive description of linear and nonlinear optical properties of captopril-capped gold nanoclusters. We synthesized Au25(Capt)18 using size-focusing method. The material was fully optically characterized in linear regime (absorption, emission, circular dichroism) [3]. Finally, two-photon absorption cross-sections and the nonlinear refractive index dispersion were determined by Z-scan method [4].

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