| SERS at 785 nm in 0.1 M KNO₃ | At acquisition times below 0.2 s per spectrum, spectral bands of distinct species appeared in only one or a few sequential spectra; averaging acquisitions to simulate exposure times above 0.5 s caused these bands to become part of the overall background intensity; with 50 ms exposure, 44 of 50 spectra showed only background and 6 showed contaminants |
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| SERS during cyclic voltammetry in 0.1 M KNO₃ | AuO formation was manifested by a broad Raman band at 570 cm⁻¹; the band area was integrated from 460 to 640 cm⁻¹, and the background was tracked from 700 to 720 cm⁻¹; the background intensity correlated strongly with appearance and disappearance of the AuO band, while repeatable background variation was also observed below the potential required for AuO formation |
| SERS during cyclic voltammetry in methanol | The 570 cm⁻¹ AuO band was not observed over the 0.0 to 1.7 V versus Ag/AgCl potential window, while background intensity remained dependent on electrode potential |
| SERS during cyclic voltammetry in 0.1 M KNO₃ | Between 0.0 and 0.7 V versus SCE, bands at approximately 800, 1000–1100, and 1350 cm⁻¹ were observed for an adsorbed contaminant species and did not appear to change during the voltammogram |
Anouk Volker, C. Maurits de Roo, Steven E. J. Bell, Wesley R. Browne. “Potential dependent modulation of surface enhanced electronic and vibrational Raman scattering intensity at roughened gold surfaces.” ChemRxiv (). https://doi.org/10.26434/chemrxiv.15007803/v1
Values presented only in Raman, cyclic-voltammetry or UV–visible absorption plots or images were not transcribed
| Cyclic voltammetry | [Os(II)(bpy)₃]²⁺ and [Ru(II)(bpy)₃]²⁺ underwent reversible one-electron oxidation at 0.80 and 1.26 V versus SCE, respectively |
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| UV–visible absorption | Neither complex absorbed at 785 nm; oxidation of [Os(II)(bpy)₃]²⁺ to [Os(III)(bpy)₃]³⁺ decreased visible absorption between 420 and 510 nm |
| SERS of physisorbed [Ru(II)(bpy)₃]²⁺ in methanol | Bands at 768, 1320, 1490, 1560, and 1605 cm⁻¹ were followed; signal decreased with increasing potential and recovered when the potential was lowered; the more positive the potential reached, the greater the relative Raman-intensity loss; background intensity also changed clearly and repeatably with potential |
| SERS of physisorbed [Os(II)(bpy)₃]²⁺ in methanol | Raman intensity decreased as the potential became more positive and recovered when the potential was scanned to less positive values; a slightly larger decrease was observed when the potential exceeded the oxidation potential, and the intensity loss remained smooth across the scan |