Structural characterization of biomolecules by resonance enhanced 2-photon ionization spectroscopy and surface-enhanced raman spectroscopy

Abstract

Single Ag Nanowire Surface-Enhanced Raman Scattering The single-crystalline free-standing Ag nanowires (NWs) with round cross-sections were synthesized by chemical vapor deposition (CVD) method. The surface-enhanced Raman scattering (SERS) of a single Ag NW was observed with the home-made microRaman system. The intensities of Raman bands of brilliant cresyl blue (BCB) coated on the NW were maximized as the incident laser polarization was perpendicular to the nanowire axis. We found that strongly anisotropic SERS enhancement could be induced by the localized excitation of even a single NW while Yang’s and Moskovits’s groups observed previously similar anisotropic enhancement for a monolayer and raft of NWs, respectively. Fabrication of Hot-Spot Line for SERS by Single Single-Crystalline Au Nanowires Strongly polarized surface-enhanced Raman scattering (SERS) of single single-crystalline Au nanowires on the Au smoothed films were observed by the home-made microRaman system. The Au nanowires were synthesized by the chemical vapor deposition method and were incubated in ethanolic solutions of adenine, benzenethiol, and BCB dye. In case of benzenethiol, the nanowires were rinsed repeatedly with absolute ethanol to remove physisorbed molecules. Strongly enhanced Raman spectrum of each molecule was observed only when the incident light was focused on the nanowire and its polarization was perpendicular to the nanowire axis. The finite difference time domain calculations show that electromagnetic (EM) field is strongly enhanced at the gap between the nanowire and the film when the incident light is illuminated on the nanowire with perpendicular polarization to the nanowire axis. Conformational Study of Tyramine and its Water Clusters by Laser Spectroscopy Tyramine and its monohydrated clusters have been investigated by several laser spectroscopic methods in a pulsed molecular beam. The conformational structures and their effects on hydration have be...