Surface-Induced Photoreduction of 4-Nitrobenzenethiol on Cu Revealed by Surface-Enhanced Raman Scattering Spectroscopy

Abstract

A copper foil etched in a dilute solution of HNO3 is free of carbon and oxygen, but the nanostructure formed thereby is highly active for surface-enhanced Raman scattering (SERS), especially when 632.8-nm radiation from a He/Ne laser is used as the excitation source. We found further that the copper foil thus prepared is also an efficient photoelectron emitter such that the SERS spectrum of 4-nitrobenzenethiol on copper is readily converted to that of 4-aminobenzenethiol under 632.8-nm radiation. This surface-induced photoreduction allowed us to prepare patterned binary monolayers on copper that showed different chemical reactivities. Using the binary monolayers as a lithographic template, we found that calcium carbonate could be grown selectively on the amine-group-terminated regions by adjusting the crystal growth conditions.

Surface enhanced raman scattering of aromatic thiols adsorbed on nanostructured gold surfaces

“…4a shows the SERS spectrum of 4-NBT adsorbed on a structured gold surface, (thickness 450 nm, 600 nm template sphere diameter). The band positions and relative intensities observed in the SERS spectra for 4-NBT on gold agree well with those in the literature [33][34]. The complete absence of the S-H stretching peak in the SERS spectrum, observable at 2548 cm -1 for pure 4-NBT (not shown in these Figures), indicates that 4-NBT is adsorbed on gold as thiolate after S-H bond cleavage.…”

“…4b shows the SERS spectrum of 4-ABT adsorbed on the surface of a nanostructured gold film (thickness 450 nm, 600 nm template sphere diameter). The band positions and relative intensities agree well with those values found in the literature [34][35] . The spectra are dominated with the stretching modes, such as ν(CC) and ν(CS) at 1577 and 1076 cm -1 respectively.…”

“…The full assignment of SERS peaks for the adsorbed 4-ABT is summarized in Table 1. [33][34][35] Both spectra in Fig. 4 show well defined SERS peaks with significant enhancement in the intensity as indicated by the high signal to noise ratio.…”

Modification of nanostructured gold surfaces with organic functional groups using electrochemical and solid-phase synthesis methodologies

“…In the case of the SSV-C-NB spectra there is no evidence of a band around 1454 cm À1 corresponding to the azo linkages between phenyl rings. The absence of the N"N stretch around 2300-2360 cm À1 (not shown) for diazonium functional group confirms that grafting was achieved by aryl radical formation [20,[55][56][57]. It is notable that the relative intensities for the diazo coupled nitrobenzene and the nitrobenzene thiol are very similar and that there are no significant shifts in the positions of the bands.…”

Surface enhanced Raman scattering of new acridine based fluorophore adsorbed on silver electrode

“…In terms of adsorption chemistry SERS is particularly valuable because there are no alternative locally sensitive methods for the investigation the state of the adsorbate. The study of adsorbates by SERS spectroscopy provides information about their transformations on the surface [10][11][12][13]. The SERS technique applied to surface-solution boundary can give information about the reorientation of adsorbates [14][15][16][17] and their interaction with the solution components [18][19][20][21].…”