Surface enhanced Raman spectra

Figure 2. Surface-enhanced Raman spectra of Fe-TsPc (A) and H2-TsPc (B) adsorbed on a sliver electrode at various potentials vs. SCE In 0.05 M H2SO4. Laser excitation line 632.8 nm output...

Figure 15.5 Surface enhanced Raman spectra of the Os(NH3)5Py(II)/(III) couple. The numbers near the spectra give the electrode potential on the SCE scale. Data taken from from Ref. 5.

The surface-enhanced Raman spectra (SERS) provide information about the extent of protonation of the species adsorbed at the silver/aqueous solution interface. The compounds investigated were 4-pyridyl-carbinol (1), 4-acetylpyridine (2), 3-pyridine-carboxaldehyde (3), isonicotinic acid (4), isonicotinamide (5), 4-benzoylpyridine (6), 4-(aminomethyl)pyridine (7) and 4-aminopyridine (8). For 1, the fraction of the adsorbed species which was protonated at -0.20 V vs. SCE varied with pH in a manner indicating stronger adsorption of the neutral than the cationic form. The fraction protonated increased at more negative potentials. Similar results were obtained with 3. For all compounds but 4, bands due to the unprotonated species near 1600 cm-1 and for the ring-protonated species near 1640 cm-1 were seen in the SERS spectra. 

Finely divided metal samples can also be prepared in the form of evaporated films in high vacuum, usually deposited on IR-transparent alkali halide plates (76-78). Such spectra are of interest in themselves, but tend to be much weaker than those obtained from the metal-particles-in-depth, oxide-supported catalysts. The rough surfaces of films of Cu, Ag, and Au, prepared by deposition on cold surfaces, can lead to very high-quality surface-enhanced Raman spectra (27, 28, 79, 80). The results from such experiments will be discussed in the later sections devoted to particular adsorbed hydrocarbons and metals, alongside the majority of spectra that are obtained on oxide-supported samples. 

Liang, E. J., Yang, Y., and Kiefer, W. (1999). Surface-enhanced Raman spectra of fulvic and humic acids adsorbed on copper electrodes. Spectrosc. Lett. 32, 689-701. 

Cyclic voltammetry of [Os(py)(NH3)5]3+ demonstrated the existence of [Os(py)(NH3)5]2+,62,90,91 and the surface-enhanced Raman spectra (SERS) of both species were measured recently,91,92 with... 

Salts of [OsL(NH3)5]3+ (L = pyrazine, pyrimidine, pyridazine) can be made by displacement of nitrogen from [Os(N2)(NH3)5]2+9° or from the triflato complex [0s(0S02CF3)(NH3)J]2+ and the ligands.62 Cyclic voltammetry showed reduction to the osmium(II) species, 90 and the surface-enhanced Raman spectra (SERS) of [Os(pyz)(HNH3)5]3+, [Os(pyz)(NH3)5]2+ and of their ammine-d5 derivatives were measured, as were the IR spectra.91... 

Surface-enhanced Raman spectra (SERS) of [Os(NH3)5bipy]3+ and its reduced form [Os(N-H3)5bipyf + have been measured.91... 

To obtain surface enhanced Raman spectra from adsorbates, special sample techniques are required to produce surface roughness or small clusters either isolated in solution or as powders at surfaces. Several techniques have been described in detail in the literature (see for example Cooney et al., 1982 Cotton, 1988). 

Rubim J, Gutz IGR, Sala O, Orville-Thomas WJ. Surface enhanced Raman spectra of benzotriazole adsorbed on a copper electrode. J Mol Struct 1983 100 571. 

Jacintho GVM, Corio P, Rubim JC (2007) Surface-enhanced Raman spectra of magnetic nanoparticles adsorbed on a silver electrode. J Electroanal Chem 603 27-34... 

Muniz-Miranda M, Cardini G, Schettino V (2004) Surface-enhanced Raman spectra of pyridine and pyrazolide on silver colloids chemical and electromagnetic effects. Theor Chem Acc 111 264-269... 

Schneider S, Grau H, Halbig P, Ereunscht P, Nickel U (1996) Stabilization of silver colloids by various types of anions and their effect on the surface-enhanced Raman spectra of organic dyes. J Raman Spectrosc 27 57-68... 

Ervin, K.M., Koglin, E., Sequaris, J.M., Valenta, P., and Numberg, H.W. (1980) Surface enhanced Raman spectra of nucleic add components adsorbed at a silver electrode. Journal of Eiectroanaiytical Chemistry, 114,... 

Surface enhanced Raman spectra of some biological molecules adsorbed at silver electrodes. Bioorganic Khimica, 7, 941-945. 

Fig. 1. Surface enhanced Raman spectra of CN in water in silver-doped sol-gel A) coated glass vials and B) filled glass capillaries. All spectra were recorded using 100 mW of 785 nm in 1-min and at a resolution of 8 cm". ...

Fig. 2. 2100 cm" peak height measured during continuous flow of a 0.01 mg/L (10 ppb) cyanide in water. Surface-enhanced Raman spectra are shown for 1 and 6 min after sample introduction. A 2.5 mL min flow rate was used and spectra were recorded every 20 sec using 100 mW of 785 nm. 

S. Farquharson, A. Gift, P. Maksymiuk and F. Inscore, Surface-enhanced Raman spectra of VX and its hydrolysis products, Spectrosc. 59, 654 (2005). 

Scheme 3.16 Generation of nanotextured Ag film (AFM height image, top right) from sputtering on UV-ozone etched PS-APIP MS film (AFM height image, top left). Surface-enhanced Raman spectra (SERS) (bottom) of benzenethiol on nanotextured Ag films (10 and 15 nm and respectively) and...

The electrochemical oxidation of the nickel is of special interest since it is a typical passivation metal in which very thin passive oxide films of a few nm thickness on the surface can cover the substrate metals efficiently. The passive oxide layer on the nickel was studied by Sikora and Mac Donald [118] who claimed that the passive film consisted of the inner nickel oxide of a barrier layer and an outer Ni(OH)2 porous or hydrated layer, in which the inner layer behaves as a p-type oxide with a cation vacancy. Oblonsky and Devine measured the surface enhanced Raman spectra of the nickel passivized in a neutral borate solution and estimated the amorphous Ni(OH)2 in the passive potential region and the NiOOH in the higher transpassive region [119]. Further, the passive films formed in the acidic and neutral solutions were assumed as partially hydrated nickel oxide [120,121]. The anodic film formed in the alkaline solution was assumed to be Ni(OH)2 in the... 

ELECTRONIC STRUCTURE STUDIES OF SURFACE ENHANCED RAMAN SPECTRA... 

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