Steiner Gerald, Sablinskas Valdas, Kitsche Marco, Salzer Reiner
Institute of Analytical Chemistry, Dresden University of Technology, Dresden, Germany.
Anal Chem. 2006 Apr 15;78(8):2487-93. doi: 10.1021/ac050481a.
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.
偏振调制红外反射吸收光谱法（PM-IRRAS）已与样品的逐步映射相结合，以表征整个表面的分子取向。已开发出一种光学装置来促进PM-IRRAS映射。当PM-IRRAS映射与普通傅里叶变换红外光谱仪结合使用时，可实现的约45微米的横向分辨率受能量限制而非衍射限制。PM-IRRAS映射用于研究附着在微结构化氧化铝/金表面的十八烷膦酸（OPA）分子的分子取向。光谱图显示，OPA优选呈斑点状附着在氧化铝表面。附着的分子形成高度有序的薄膜。发现吸附在金上的膦酸主要以三齿键合模式存在时，有序度较低。结果表明，PM-IRRAS映射在揭示附着在表面的超薄膜内的不均匀性方面具有相当大的潜力。
