TY - CONF A1 - Streeck, C. A1 - Nutsch, A. A1 - Dietrich, P. A1 - Fischer, Tobias A1 - Grötzsch, D. A1 - Nietzold, Carolin A1 - Malzer, W. A1 - Rurack, Knut A1 - Beckhoff, B. A1 - Unger, Wolfgang T1 - Characterization of bio-molecular surfaces and liquids by means of reference-free X-ray spectrometry N2 - An increasing field of application for X-ray spectrometry and related analysis techniques is the investigation of tailor made functional surfaces modified by organic molecules. For a detailed understanding and further development of such functionalized surfaces, a quantitative determination of the surface density of molecular species or even specific functional groups is required. By means of reference-free X-Ray Fluorescence (XRF) spectrometry such customized surfaces can be analyzed quantitatively, when using specific marker elements. A chemical analysis of molecular bonds can be accomplished by X-Ray Absorption Spectroscopy in the Near-Edge region (NEXAFS). Especially in the soft X-ray range an access to relevant light elements like carbon C, nitrogen N and oxygen O is possible. Especially, the characterization of liquids and solid-liquid interfaces aiming at the determination of bio-molecular moieties (functional groups) is of great interest. The characterization of such systems requires the analysis of bio-molecules in their liquid environment. For the understanding of (biomolecular) reactions and binding processes the verification and quantification of biomolecule immobilization is essential. However, the analysis in the soft-X-ray range involves a higher experimental effort. In this contribution various successful applications of the characterizations of organofunctionalized surfaces, solid-liquid interfaces and liquids containing bio-molecular species by means of reference-free X-ray spectrometry will be presented. The experiments were performed at the plane-grating monochromator beamline (PGM-U49) in the soft X-ray range at the synchrotron radiation facility BESSY II. Using calibrated instrumentation and a quantification approach based on atomic fundamental parameters a quantitative access without any calibration sample or reference material is possible. In a complementary analysis by X-Ray Photoelectron Spectroscopy (XPS) and fluorescence measurements based on laserexcitation in the optical light spectrum the functional-group density of silane monolayers were determined. Here, the nitrogen atoms of the head-group of the label molecule employed could be used as specific marker for the reference-free quantitative XRF analysis and is used for traceable calibration of XPS and fluorescence spectroscopy. Furthermore, a novel UHV-compatible liquid-cell developed to investigate liquids and solidliquid interfaces will be presented. Protein attachment at the solid-liquid interface was investigated by detection of the characteristic N1s→π*(O=C-N) amide bond resonance in the N K-edge NEXAFS by using ultra-thin epoxy-functionalized SiC-windows. T2 - European Conference on X-Ray Spectrometry (EXRS) CY - Gothenburg, Sweden DA - 19.06.2016 KW - Bio-molecular surfaces KW - NEXAFS KW - XPS KW - XRS PY - 2016 AN - OPUS4-36965 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -