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The complex [Cu4(tu)7](SO4)2·H2O was isolated by addition of thiourea to a copper(II) sulfate electrolyte solution consisting of 2 M H2SO4 and 0.7 M CuSO4. The crystal structure of this complex was solved by X-ray methods and highlighted a [Cu4(tu)7]4+ adamantane cluster. A copper(I)−thiourea cluster of this stoichiometry has not been previously reported. The X-ray structure is refined to residual R = 0.0447 for 4093 observed reflections. Crystals are orthorhombic, of space group Pbca, with Z = 8 in a cell of dimensions a = 10.414(3), b = 17.909(3), and c = 35.818(3) Å. The copper atoms lie in a tetrahedral arrangement in which one of the copper atoms is four-coordinate, while the other three display trigonal planar coordination with Cu···Cu distances of 2.899(2)−2.967(2)Å. The copper−thiourea clusters are interlinked by sulfate ions, which strongly interact with the thiourea ligands through hydrogen bonds. The infrared and Raman spectra of the title compound and of the related copper(I) thiourea complexes [Cu2(tu)5](SO4)·3H2O, [Cu2(tu)6](SO4)·H2O, [Cu4(tu)6](NO3)4·4H2O, and [Cu4(tu)9](NO3)4·4H2O were recorded and assigned, and the dependence of ν(CuS) on the coordination environment of the copper was established.

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Surface-enhanced Raman scattering (SERS) spectroscopy has been applied to identify species formed during gold leaching in thiosulfate media. Surface coverages of copper and sulfur for various thiosulfate dissolution systems were determined electrochemically and by X-ray photoelectron spectroscopy. A gold sulfide monolayer was shown to be formed slowly in the potential region where leaching occurs. At higher potentials, more sulfur is adsorbed but, rather than creating a multilayer, sulfur-sulfur linkages are formed with the sulfur atoms no longer being covalently bonded to gold. SERS spectra show the presence of polythionates on the gold surface in addition to gold sulfide and S0 . At longer exposure times, thiosulfate is oxidized to elemental sulfur and sulfate, both products being identified by normal Raman spectroscopy from the leach solution. In typical thiosulfate/ammonia/copper(II) leach solutions, copper is present on the surface of gold in addition to sulfur. In these situations, ammonia is coadsorbed.

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A silver surface, suitable for Fourier transform surface-enhanced Raman scattering (FT-SERS), has been prepared by subjecting a polished silver surface to an oxidation-reduction cycle in an electrochemical cell with KCl solution as the electrolyte. The surface produced by this method is shown, by scanning electron microscopy, to be very rough. The preparation of this surface is quite reproducible because the significant parameters of starting surface, electrolyte concentration, and potential can all be well controlled. After removal from the cell followed by washing and drying, organic compounds can be placed on the surface as solutions in aqueous or organic solvents, or by exposure of the surface to vapor. Typically, good FT-SERS spectra are obtained from 0.1–2 μg of sample, after evaporation of the solvent. These experiments were not optimized for minimum detection limits. The technique is very simple, and spectra can be obtained with ease for a wide variety of compounds. Most compounds gave FT-SERS spectra which were similar to their solid Raman spectra; however compounds containing groups expected to interact strongly with the silver surface gave FT-SERS spectra very different from their normal Raman spectra.

To better understand and ascertain the mechanisms of flotation reagent interaction with rare earth (RE) minerals, it is necessary to determine the physical and chemical properties of the constituent components. Seven rare earth oxides (CeO2, Er2O3, Nd2O3, Tm2O3, Yb2O3, La2O3, and Tb4O7) that cover the rare earth elements (REEs) from light to heavy REEs have been investigated using Raman spectroscopy. Multiple laser sources (wavelengths of 325 nm, 442 nm, 514 nm, and 632.8 nm) for the Raman shift ranges from 100 cm−1to 5000 cm−1of these excitations were used for each individual rare earth oxide. Raman shifts and fluorescence emission have been identified. Theoretical energy levels for Er, Nd, and Yb were used for the interpretation of fluorescence emission. The experimental results showed good agreement with the theoretical calculation for Er2O3and Nd2O3. Additional fluorescence emission was observed with Yb2O3that did not fit the reported energy level diagram. Tb4O7was observed undergoing laser induced changes during examination.