title: Gold-coated silver dendrites as SERS substrates with an improved lifetime.
abstract: Nanostructured silver is known to yield the highest signal-enhancement factors in surface-enhanced Raman spectroscopy, but its low chemical stability toward oxidation presents a challenge in the realization of Ag-based SERS substrates with long operating lifetimes. Here, a study of the long-term stability of silver dendrites as SERS substrates is reported. SERS spectra of 1,2-benzenedithiol monolayers on Ag dendrites, acquired over a period of time in excess of 1 year, shows appreciable degradation with time. However, no degradation is observed in the spectra of monolayers deposited on Ag dendrites that were coated with a monolayer-thin Au film deposited by an immersion plating process. X-ray photoelectron spectra confirm the oxidation of the uncoated Ag dendrites whereas no chemical changes are detected in the Au-coated ones. These results suggest that the galvanic displacement of Au on preformed Ag nanostructures provides a suitable route to producing SERS-active substrates with long operating and/or shelf lifetimes.
authors.affiliation: Department of Chemical and Biomolecular Engineering, University of California, Berkeley, California 94720, USA.
authors.forename: Albert
authors.initials: A
authors.lastname: Gutés
authors.forename: Roya
authors.initials: R
authors.lastname: Maboudian
authors.forename: Carlo
authors.initials: C
authors.lastname: Carraro
mesh_terms: D001554:Benzene / Q000737:chemistry; D003712:Dendrites / Q000737:chemistry*; D004355:Drug Stability; D006046:Gold / Q000737:chemistry*; D012834:Silver / Q000737:chemistry*; D013059:Spectrum Analysis, Raman / Q000379:methods*; D013499:Surface Properties; D013997:Time Factors
chemical_list: D012834:Silver; D006046:Gold; D001554:Benzene