title: Fluorescence and Raman study of pH effect on the adsorption orientations of methyl red on silver colloids.
abstract: We report the fluorescence and surface-enhanced Raman scattering (SERS) analysis of methyl red (MR) isomers (o-MR, m-MR, p-MR) on silver (Ag) colloids at different pH conditions. The changes in simultaneous fluorescence quenching around 400 nm accompanied by enhancement around 540 nm with pH are closely related to energy transfer efficiency and the interaction between the carboxylic group and the Ag surface. The change of SERS signals with pH values can be ascribed to different adsorption orientations of MR on the Ag surface, from near flat (o-MR) to near perpendicular (p-MR).
authors.affiliation: Department of Chemistry, Center for Nano-technology, and Research Center for Analysis and Identification, Chung Yuan Christian University, Jhongli, Taoyuan, 32023, Taiwan. slee@cycu.edu.tw
authors.forename: Szetsen
authors.initials: S
authors.lastname: Lee
authors.forename: Jian-How
authors.initials: JH
authors.lastname: Wong
authors.forename: Shiao-Jun
authors.initials: SJ
authors.lastname: Liu