Paper AS1-ThM11
Large Area Combinatorial Near Edge X-ray Absorption Fine Structure Images: Parallel Process Determination of Molecular Bond Concentration and Orientation on Surfaces

Thursday, November 12, 2009, 11:20 am, Room C2

We show that simultaneous molecular orientation and bond chemistry of large area (18 mm x 13 mm) planar chemically heterogeneous surfaces can be obtained by combining near edge X-ray absorption fine structure (NEXAFS) spectroscopy, a new parallel process magnetic field electron yield optics detector, and a full field incident soft X-ray beam on the sample. The rapid parallel process magnetic field electron yield optics detector (LARIAT:Large ARea Imaging Analytical Tool) produces a series of two-dimensional NEXAFS spatial images as the incident soft X-ray energy is scanned above a K or L absorption edge. The image stack reveals information about the chemistry (including bond concentration) and orientation of the surface-bound molecules with 50-micron planar spatial resolution and sub-monolayer molecular sensitivity. The power of the combinatorial imaging NEXAFS method is illustrated by simultaneously probing the concentration and molecular orientation of single-strand DNA micro array sensors, semifluorinated molecular gradients, and organic electronic combinatorial device arrays. Other possible applications described include the surface orientation and chemistry of continuously graded polymer films and graded or patterned self-assembled monolayers that exhibit tunable surface properties of potential use in nanotechnology. We also envision combinatorial imaging NEXAFS as an insitu probe for catalyst discovery using micro arrays to directly image catalytic chemical activity of thousands of catalysts simultaneously under reaction conditions.