| Composition-modulated alloy structures (CMS) of either silver and palladium or copper and nickel were found to effectively support surface-enhanced Raman scattering (SERS) in the electrochemical environment. SERS of adsorbed pyridine was observed on the Ag-Pd CMS when the top modulation layer was silver, and on the Cu-Ni CMS when copper was on top. Mild electrochemical anodization of these surfaces was needed to observe the effect. The same CMSs that were SERS active also gave rise to enhanced second harmonic generation under infrared excitation.;A series of copper-nickel bulk alloys were tested for electrochemical SERS activity with pyridine and triethyl-enediamine as the surface adsorbed molecules. Using potential step difference Raman spectroscopy on the unroughened surfaces it was found that the Cu-Ni alloys still exhibit SERS activity up to a nickel content of 20 mole percent. The damping mechanism in the Cu-Ni case must be less severe than in other alloy systems reported to date.;A liquid nitrogen cooled stimulated Raman shifter was described which produced tunable frequencies from the near infrared to the vacuum ultraviolet. The output was directly interfaced to a vacuum chamber. The unenhanced Raman spectra of pyrazine and benzene multilayers adsorbed on cold silicon in high vacuum were reported. The first resonance Raman spectra of aqueous pyridine and pyrazine solutions were taken in a windowless circulating jet.;A new surface probe molecule, tris(4,7-diphenyl-1,10-phenanthroline)iron(II) sulfate, was found to adsorb from aqueous solution as a monolayer on polycrystalline silver. Strong resonance Raman scattering was observed using a cw Nd:YAG 532 nm laser, but use of 10 Hz Nd:YAG 532 nm pulses at even less average power resulted in the rapid loss of signal, indicating probable desorption.;Surface resonance Raman spectra could not be obtained in the ultraviolet and calculations show that desorption or decomposition is likely to occur. |
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