SERS investigation of the co‐adsorption of nicotinic acid and 3‐acetylpyridine on silver electrodes

Abstract

The pHdependent solution Raman spectra of nicotinic acid and Sacetylpyridine are reported in the wavenumber range 500-1750 cm-'. The changes with pH in the spectra of both molecules were correlated with the structure of the predominant solution species. Band assignments were carried out by referring to the spectra of the pure compounds and of related molecules. The surface-enhanced Raman spectra of nicotinic acid and facetylpyridine coadsorbed on polycrystalline silver electrodes were measured as a function of applied potential. The surface-active species were identified according to the solution and surface Raman shifts of the individual components. A surface configuration involving the interaction of nicotinic acid and 3-acetylpyridine is proposed to explain the observed spectra.

Combination of Raman Spectroscopy and Mass Spectrometry for Online Chemical Analysis

“…Figure A shows the resultant SERS spectrum (red curve) of sample obtained from mixing nicotinic acid with Ag NPs. The intense peak at 1034 cm –1 is due to trigonal ring breathing mode . The peaks at 845 and 1598 cm –1 are attributed to ring vibration of nicotinic acid .…”

“…The intense peak at 1034 cm −1 is due to trigonal ring breathing mode. 26 The peaks at 845 and 1598 cm −1 are attributed to ring vibration of nicotinic acid. 26 Peak at 1389 cm −1 is assigned to symmetric stretching mode of the COO − group.…”

“…26 The peaks at 845 and 1598 cm −1 are attributed to ring vibration of nicotinic acid. 26 Peak at 1389 cm −1 is assigned to symmetric stretching mode of the COO − group. 26 In the absence of Ag NPs in the sample, the Raman spectrum of the same nicotinic acid sample showed a weak peak at 1034 cm −1 (black curve, Figure 2A).…”

“…26 Peak at 1389 cm −1 is assigned to symmetric stretching mode of the COO − group. 26 In the absence of Ag NPs in the sample, the Raman spectrum of the same nicotinic acid sample showed a weak peak at 1034 cm −1 (black curve, Figure 2A). The corresponding mass spectrum of nicotinic acid was dominated by the intense peak at m/z 122, which is derived from deprotonated nicotinic acid (Figure 2B).…”