title: Polarization modulation-infrared reflection absorption spectroscopic mapping.
abstract: Polarization modulation-infrared reflection absorption spectroscopy (PM-IRRAS) has been coupled with a stepwise mapping of the sample in order to characterize the molecular orientation across the surface. An optical setup has been developed to facilitate the PM-IRRAS mapping. With PM-IRRAS mapping used in conjunction with a common FT-IR spectrometer, the achievable lateral resolution of approximately 45 mum is energy-limited rather than diffraction-limited. PM-IRRAS mapping was used to study the molecular orientation of octadecanephosphonic acid (OPA) molecules attached on a microstructured aluminum oxide/gold surface. The spectroscopic map reveals that OPA is preferably spotty attached on the aluminum oxide surface. The attached molecules form a highly ordered film. A lower degree of ordering was found for phosphonic acid adsorbed on gold mainly in a tridentate bonding mode. Results demonstrate that PM-IRRAS mapping has a considerable potential for revealing inhomogenities within ultrathin films attached on a surface.
authors.affiliation: Institute of Analytical Chemistry, Dresden University of Technology, Dresden, Germany. gerald.steiner@chemie.tudreden.de
authors.forename: Gerald
authors.initials: G
authors.lastname: Steiner
authors.forename: Valdas
authors.initials: V
authors.lastname: Sablinskas
authors.forename: Marco
authors.initials: M
authors.lastname: Kitsche
authors.forename: Reiner
authors.initials: R
authors.lastname: Salzer
mesh_terms: D000042:Absorption; D000473:Alkanes / Q000737:chemistry*; D000537:Aluminum Oxide / Q000737:chemistry*; D006046:Gold / Q000737:chemistry*; D008051:Lipid Bilayers / Q000737:chemistry*; D008560:Membrane Fluidity; D063065:Organophosphonates / Q000737:chemistry*; D012680:Sensitivity and Specificity; D017550:Spectroscopy, Fourier Transform Infrared / Q000295:instrumentation / Q000379:methods*; D013499:Surface Properties
chemical_list: D000473:Alkanes; D008051:Lipid Bilayers; D063065:Organophosphonates; D006046:Gold; D000537:Aluminum Oxide; C022883:octadecane