Dopamine Molecules on Aucore−Agshell Bimetallic Nanocolloids: Fourier Transform Infrared, Raman, and Surface-Enhanced Raman Spectroscopy Study Aided by Density Functional T

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• 作者：Surojit Pande ; Subhra Jana ; Arun Kumar Sinha ; Sougata Sarkar ; Mrinmoyee Basu ; Mukul Pradhan ; Anjali Pal ; Joydeep Chowdhury ; Tarasankar Pal
• 刊名：Journal of Physical Chemistry C
• 出版年：2009
• 出版时间：April 30, 2009
• 年：2009
• 卷：113
• 期：17
• 页码：6989-7002
• 全文大小：470K
• 年卷期：v.113,no.17(April 30, 2009)
• ISSN：1932-7455

文摘

Adsorption of dopamine (DA) on a Au_core−Ag_shell bimetallic nanocolloidal surface has been investigated using surface-enhanced Raman spectroscopy (SERS). The normal Raman spectra (NRS) of DA molecules in bulk and in aqueous solution have been investigated in depth. The vibrational signatures, as observed from the Raman and FTIR spectra of the molecule, have been assigned from the potential energy distributions. The pH-dependent NRS of the DA molecule in aqueous solution has been recorded to elucidate the protonation effect and preferential existence of different forms of the molecule. The pH-dependent SERS spectra of the molecule adsorbed on the bimetallic Au_core−Ag_shell nanocolloidal surface are also reported. The enhancement of bands in the pH-dependent SERS spectra suggests that the molecules are adsorbed onto the bimetallic Au_core−Ag_shell surface with the molecular plane tilted with respect to the silver surface of Au_core−Ag_shell bimetallic nanoparticles. The model study authenticates the spectral disposition and orientation of the molecule. Thus, experiment and theory keep abreast of the variety of DA structures envisaged from SERS studies on a new substrate.