Synchrotronstrahlungsinduzierte GIXRF mit Absorptionsspektroskopie

Total Reflection X-ray Fluorescence Analysis (TXRF) is a special method of energy dispersive X-ray Fluorescence Analysis extending the analytical power to the ultra trace element range (Detection limits in the pg (10-12 g range) with X-ray tube excitation. When performed at Synchrotron radiation (SR) sources with a multilayer monochromator, itallows to achieve detection limits down to the fg(10-15 g) range. Using a high resolution crystal monochromator instead of a multilayer monochromator X-Ray Absorption spectroscopy (XANES, EXAFS) can be performed allowing speciation of trace elements and determination of their chemical environment. Measuring the angle dependence of the fluorescence signal the method is called GIXRF (Grazing incidence XRF), which is a powerful technique for non-destructive depth-profiling especially sensitive to near surface layers and characterization of thin layers up to a few hundred nanometers. GIXRF provides information on depth distribution and total dose of the elements in the layers. A combination of the GI-XRF with absorption spectroscopy allows to gain information on the local structure of the element of interest and an insight in the physical/chemical properties related to its incorporation in the material (e.g. electrical activity in microelectronics related ion implants). Aim of the project: RTXRF-XANES: Determination of Rhodium oxidation state in Rh treated cancer cells (cooperation with Prof. G. Zaray, and Dr. N. Szoboszlai from ELTE Budapest and Dr. K. Appel from HASYLAB@DESY, Hamburg). The TXRF-XANES results will help to understand the mechanism of the biological effect of Rh complexes and to study the antitumor activity and toxicity of the different complexes. IXRF of As implants for ultra shallow junctions (cooperation with Dr. G. Pepponi and D.I. Dr. F. Meirer from FBK-irst, Trento and Prof. P. Pianetta, SSRL, California). Determination of degree of dopant activation achieved by the current implantation and annealing techniques. GIXRF-EXAFS/XANES will be used to analyze the local coordinate structure around As ions. I-XRF + X-ray reflectivity (XRR) - thin layer analysis (coop: Dr. Pepponi, Dr. Meirer, Dr. Morales from CIMAP, ENSICAEN, Caen, France, Dr. J. Göttlicher from ANKA, Karlsruhe, Germany, and Dr.Appel). The measurement setup, protocol (for lab and SR measurements) and the evaluation software should be developed to use GIXRF + XRR for the comprehensive non=destructive analysis of thin layers on wafer material for semiconductor application (high k material) as well as rare earth doped Silicon rich oxide films that could help to increase the efficiency of thin film solar cells.

Synchrotron radiation induced TXRF (SR-TXRF) is a micro analytical technique, which offers detection limits in the femtogram (10-15 g) range for most elements. The technique was coupled with X-ray Absorption Spectroscopy (XAS) to gain information on the chemical environment of the specific elements of interest at an ultra-trace level. In this project rhodium (Rh) as well as iron (Fe) speciation in cancer cell lines was successfully performed by SR-TXRF-XANES. It was found that Fe can be stored in at least two different complexes in the cell as an Fe pool. (1 publication). The investigation of Rh complexes accumulated in cells helps to understand why the different Rh compounds have different effectiveness against cancer cells (1 publication). Furthermore the SR-TXRF sample chamber (designed and produced by ATI in cooperation with Uni Hamburg) previously installed at HASYLAB, Hamburg was transferred to BESSY, BAMline in Berlin after the shutdown of HASYLAB. It was put into operation under our guidance and using our expertise and is now available for all BESSY users. Another research activity was the development of Grazing incidence XRF (GIXRF) combined with X-ray reflectometry (XRR): Varying the angle of incidence around the critical angle for total reflection the technique is call GIXRF and in combination with XRR, depth profiles and thin films in the nanometer range can be characterized. The existing measurement setup in the lab was extended, so that data for GIXRF and XRR measurements can be collected simultaneously (1 publication). A versatile software for data evaluation (JGIXA) was developed, suitable for data obtained with the lab setup as well as with SR-GIXRF +XRR setups (1 publication). It could be shown that combining GIXRF and XRR leads to unambiguous results not only for the characterization of near surface layers (element, thickness with accuracy of 0.5 nm and density can be determined) but also for depth profiles and dose determination of implants. The method was validated with secondary ion mass spectrometry (SIMS) measurements (1 publication). Several setups at various SR facilities (ESRF, ANKA, HASYLAB, ELETTRA) have been tested, only two SR-GIXRF+XRR setups turned out to provide useful results. A new international collaboration with CEA-LETI, Grenoble, Fr (Dr. E. Nolot) was established and together with his group thin films for photovoltaic applications have been characterized (1 publication). Within this project it could be demonstrated that TXRF analysis in combination with XAS analysis is a powerful and multifunctional method to study the cytotoxicity of trace elements in the field of cancer research. Further output was the development of a setup in the lab in comparison to synchrotron beamline setups as well as a versatile software for data evaluation for the characterization of implants and thin films in the nanometer range, which attracted international attention leading to intensive new cooperations.