Low frequency vibrational interactions between gold surfaces and dissolved halide were investigated by surface enhanced Raman spectroscopy (SERS). Experiments were conducted with NaF, NaCl, NaBr, and NaI salts with commercial gold SERS substrates as well as with citrate-coated gold nanoparticles (cit-AuNP). The Raman active gold-halide interactions were isolated with the aid of signal enhancement from nanoscale surface features present on the aggregates formed by cit-AuNP in the presence of salt (Figure 1). The Raman shift trends of the Au-X<sup>-</sup> SERS bands corroborate with the corresponding covalent interaction strength as estimated by force constant calculations. Time-resolved superpositioned SERS spectra indicate that the Au-X<sup>-</sup> signal increases with time and this trend is concomitant with AuNP aggregate formation (Figure 2). This SERS-detectable interaction provides new routes for aqueous halide sensing.

Low frequency vibrational mode surface enhanced Raman spectroscopy characterization of gold interactions with aqueous halides

253rd National Meeting (2017)

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