Mapping Surface Chemistry and Molecular Orientation with Combinatorial Near‐Edge X‐Ray Absorption Fine Structure Spectroscopy

Abstract

AbstractSummary: Mapping the bond chemistry and molecular orientation of self‐assembled monolayer gradients on flat surfaces and reaction intermediates in catalyst arrays is made possible using combinatorial near‐edge X‐ray absorption fine structure (NEXAFS) spectroscopy. These spatially resolved NEXAFS maps have been made by utilizing synchrotron‐based NEXAFS spectroscopy in conjunction with a computer controlled precision sample manipulator. The NEXAFS maps reveal bond concentration, rehybridization, and orientation of the surface‐bound molecules with sub‐millimeter planar spatial resolution and sub‐monolayer molecular sensitivity. The wide applicability of the combinatorial NEXAFS method is illustrated by mapping: (1) the concentration and molecular orientation of semifluorinated molecules in molecular gradients; (2) the concentration of amino groups in molecular gradients used for nanoparticle templating, and (3) the rehybridization of propylene intermediates on zeolite catalyst arrays used for measuring solid‐state acidity and catalyst activity.The principle of “combinatorial” NEXAFS. The molecular gradient is indicated pictorially by the shading on the specimen.magnified imageThe principle of “combinatorial” NEXAFS. The molecular gradient is indicated pictorially by the shading on the specimen.