1 |
THE EFFECT OF UNDERPOTENTIALLY DEPOSITED LEAD THIN FILMS ON SURFACE ENHANCED RAMAN SCATTERING AT SILVER ELECTRODES.GUY, ANITA LOUISE. January 1986 (has links)
This dissertation details the effect of underpotentially deposited (UPD) Pb on the surface enhanced Raman scattering (SERS) ability of roughened polycrystalline Ag electrodes. The deposition of monolayer and submonolayer amounts of Pb results in a quenching of the SERS response for pyridine and Cl⁻ adsorbed at Ag electrodes. Various factors which may contribute to the loss of SERS intensity are investigated. The most significant factors include changes in surface roughness features brought about by Pb UPD, changes in surface electronic properties of Pb-modified Ag and changes in a chemical contribution to surface enhancement. Possible changes in surface roughness properties of the Ag electrode due to Pb deposition are examined using scanning electron microscopy (SEM) and SERS reversibility studies. SEMs of roughened Ag electrodes before and after Pb monolayer deposition show no significant change in the morphology of the larger roughness features. However, the deposition and stripping of 60 - 70% of a Pb monolayer results in a loss of ca. 50% of the original SERS intensity for both adsorbate bands. This irreversible loss of SERS intensity is attributed to the destruction of atomic scale roughness (ASR). These results suggest that ca. 50% of the observed SERS response arises from a mechanism involving ASR. In addition, the destruction of ASR is shown to be largely responsible for the quenching of SERS at higher Pb coverages. The morphology of the SERS quenching profiles at lower Pb coverages for pyridine and Cl⁻ varies as a function of excitation wavelength. Experimental quenching profiles are compared with theoretical quenching profiles based on an electromagnetic contribution to SERS. Theoretical quenching profiles are calculated using a model for electromagnetic enhancement at a overlayer-covered ellipsoids proposed by Murray. The experimental results for both adsorbates are in agreement with the theoretical predictions for laser excitation in the blue. Experimental results in the green and red wavelength regions are best explained in terms of photoassisted charge-transfer mechanisms for surface enhancement.
|
2 |
Part I. Surface-enhanced Raman scattering (SERS) methodology and applications to small organic molecules ; Part. II. Luminescence in the Raman spectra of aluminum oxide /Zuo, Chen, January 1900 (has links)
Thesis (Ph. D.)--West Virginia University, 2002. / Title from document title page. Document formatted into pages; contains xiii, 139 p. : ill. Vita. Includes abstract. Includes bibliographical references.
|
3 |
Surface-enhanced raman scattering and surface-enhanced hyper raman scattering : a systematic study of various probing molecules on novel substrates /Huang, Qunjian. January 2003 (has links)
Thesis (Ph. D.)--Hong Kong University of Science and Technology, 2003. / Includes bibliographical references. Also available in electronic version. Access restricted to campus users.
|
4 |
Resonance raman and surface enhanced raman studies of hemeproteins and model compoundsTanaka, Tomoyoshi 12 1900 (has links)
No description available.
|
5 |
Fabrication and characterization of substrate materials for trace analytical measurements by surface enhanced raman scattering (SERS) spectroscopy technique /Vabbilisetty, Pratima. January 2008 (has links)
Thesis (M.S.)--Youngstown State University, 2008. / Includes bibliographical references (leaves 75-77). Also available via the World Wide Web in PDF format.
|
6 |
Characterization and growth analysis of two types of thin films formed on copper surfaces an inorganic chromium containing film and an organic film formed via reduction of diazonium ions /Hurley, Belinda L. January 2004 (has links)
Thesis (Ph. D.)--Ohio State University, 2004. / Title from first page of PDF file. Document formatted into pages; contains xvi, 205 p.; also includes graphics (some col.). Includes bibliographical references (p. 196-205).
|
7 |
Sensor molecules for the rapid and specific detection of bioavailable metals /Strickland, Aaron D. January 2005 (has links)
Thesis (Ph. D.)--University of Wyoming, 2005. / Includes bibliographical references (leaves 209-216).
|
8 |
Surface-enhanced hyper raman and surface-enhanced raman scattering : novel substrates, surface probing molecules and chemical applications /Xie, Yu-Tao. January 2007 (has links)
Thesis (Ph.D.)--Hong Kong University of Science and Technology, 2007. / Includes bibliographical references. Also available in electronic version.
|
9 |
Surface-enhanced Raman and electron spectroscopic investigations of lead-modified silver surfaces.Kellogg, Diane Schneider January 1989 (has links)
Surface enhanced Raman scattering (SERS) is a powerful means for obtaining vibrational data from the metal/electrolyte or metal/gas interfacial environment. However, SERS is only observed for a limited number of metal surfaces under certain experimental conditions. Before this method can become a universal tool, the enhancement mechanism(s) must be understood. The results reported in this dissertation assess both electronic and chemical contributions to the SERS mechanism. The electronic properties of the metal are altered by systematic deposition of Pb or Cu onto a substrate that supports intense SERS, Ag. The chemical nature of the interface is altered with different probe molecules. The effect of Pb deposition on the SERS enhancing ability of Ag electrodes has previously been investigated with strongly adsorbed probe molecules. The behavior of cyanide species in the presence of Pb⁺² is complicated by the necessity of maintaining low solution pH to prevent Pb(OH)₂ precipitation; thus, the predominant solution species is HCN. Although previous reports state that no SERS can be detected from cyanide-containing solutions below pH 6, intense SERS signals can be obtained at pH 2 if sufficiently positive electrode potentials are maintained. The two unresolved SERS bands observed in acidic solutions are attributed to HCN which interacts with the Ag surface in end-on and side-on configurations. The predominant effect of Pb deposition on HCN SERS is HCN displacement. Enhancement due to charge transfer processes is not significant, while electromagnetic effects dictate the residual SERS intensity remaining after the initial HCN displacement. The supporting electrolyte anion affects the rate of change of the potential dependent C≡N stretch in basic CN⁻ media. A correlation between the rate of frequency change and anion charge/radius ratio was observed at potentials near and slightly negative of the Ag potential of zero charge in basic CN⁻ media. These results demonstrate the extraordinary sensitivity of SERS to interfacial conditions. The contributions from chemical and electromagnetic enhancement are further assessed by following excitation wavelength dependence of the SERS intensity of pyridine and Cl⁻ as a function of Cu coverage. Contributions from both are observed, but chemical enhancement is less evident for Cu than for Pb deposition. This is related to the smaller change in work function that occurs as a consequence of Cu versus Pb deposition on Ag surfaces.
|
10 |
SURFACE ENHANCED RAMAN SCATTERING OF INTERFACIAL HALIDE IONS AND WATER AT SILVER ELECTRODES IN THE PRESENCE OF LEAD (SERS, ADSORPTION, DEPOSITION).Coria Garcia, Jose Conrado. January 1985 (has links)
No description available.
|
Page generated in 0.1078 seconds