How hottest geometries and adsorptive parameters influence the SER(R)S spectra of Methylene Blue molecules adsorbed on nanocolloidal gold particles of varied sizes?

• SER(R)S of Methylene Blue on gold nanocolloid has been recorded.
• Concentration of unadsorbed probe molecule was estimated.
• Adsorptive parameters, free energy of adsorption of the molecule were estimated.
• Hottest among the hot geometries have been identified from 3D-FDTD simulations.

The SER(R)S spectra of Methylene Blue (MB) molecule adsorbed on gold nanocolloidal particles (AuNCs) have been investigated. The adsorptive parameters of the molecule adsorbed on AuNCs have been evaluated with the aid of Fluorescence Spectroscopy study. Fluorescence spectroscopic studies have been further applied to understand the concentration of probe molecule actually adsorbed on AuNC surfaces. Gigantic enhancements ∼106–1016 orders of magnitude have been recorded for the enhanced Raman bands in the SER(R)S spectra. Three-dimensional Finite Difference Time Domain (3D-FDTD) simulations studies have been carried out to predict the distributions of electric fields around the possible nanoaggregated hot geometries considered to be responsible for the huge enhancements of SER(R)S bands of the MB molecule.

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