Surface enhanced Raman spectroscopy on copper hydrosols

Surface-Enhanced Raman Scattering from Copper Nanoparticles Obtained by Laser Ablation

“…Colloidal metals have been widely used in SERS experiments because they are easy to prepare and generally provide strong Raman enhancements due to the highly nanostructured surface of the colloidal particles. Copper colloids, however, have received less attention in comparison to silver and gold suspensions, owing to their instability. − Hence, stabilizing agents were often necessary for these colloidal systems. − However, copper nanoparticles find large employment as a catalyst − and in biochemical applications, , and this widely justifies our efforts to obtain stable Cu colloidal particles with sizable SERS efficiency. This latter has been tested by observing the Raman spectra of phen and bipy adsorbed on Cu nanoparticles obtained by laser ablation, as above-reported.…”

“…Copper colloids, however, have received less attention in comparison to silver and gold suspensions, owing to their instability. [33][34][35][36][37][38][39][40][41] Hence, stabilizing agents were often necessary for these colloidal systems. [42][43][44][45][46][47][48] However, copper nanoparticles find large employment as a catalyst [49][50][51] and in biochemical applications, 52,53 and this widely justifies our efforts to obtain stable Cu colloidal particles with sizable SERS efficiency.…”

Ultrasensitive Chemical Analysis by Raman Spectroscopy

“…Silver, gold, and copper have been prepared in a variety of ways to generate SERS-active substrates for applications in various environments. SERS substrates used for analytical applications include roughed silver electrodes, silver films made by vapor deposition 104 or photoreduction, silver and gold colloidal particles self-assembled into polymer-coated substrates, electrochemically prepared silver oxide, silver particles layered onto etched polymer substrates, and colloidal metal particles in hydrosols. , Common SERS-active substrates for analytical use provide comparatively low enhancement factors ranging between 10 3 and 10 6 , which can be increased by exploitation of the resonance Raman effect if the target molecule has electronic transitions in the range of the excitation laser. For typical SERS-active substrates, calibration plots exhibit a linear response over 2−3 orders of magnitude. ,, The precision expected from a SERS experiment is typically 15−20% relative standard deviation. , …”

Comparison of SERS effectiveness of copper substrates prepared by different methods: what are the values of enhancement factors?

“…Colloidal systems can be prepared by chemical reduction of a cupric salt using borohydride as the reduction agent. [28,29] In our previous studies, we compared large substrates of different metals, namely, silver [30] , gold [31] and copper [24] . It was observed that the SERS spectra measured on copper substrates were comparable with those obtained on silver or gold substrates, but the values of the EFs were not estimated.…”