jeudi 29 juin 2017 à 14H00

CINaM - Salle Raymond Kern

Juris Purans

Institute of Solid State Physics, University of Latvia, Latvia

Recent achievement in Synchrotron Radiation X-ray absorption spectroscopy: Near field X-ray SPM - new tool for nanoscience

In the last years, the X-ray absorption (XAS) techniques have undergo remarkable development: (i) experiments with unprecedented femtometer accuracy [1], (ii) experiments with nanoscale lateral resolution. Nevertheless, investigations of complex nanostructured materials used in modern technologies require special X-ray experimental techniques able to imaging simultaneously topography and chemical mapping on the nanometer scale.

Near Field X-ray Spectromicroscopy is a fully new approach for the detailed investigation of nanostructures down to the nanometer level. The extremely high lateral resolution of Local Probe Microscopies (LPM, AFM, STM) makes them among the most largely used in nanoscience. However, these tools suffer of a lack in chemical sensitivity. On the other hand, far field X-ray spectroscopy probes the chemical and structural properties of materials. A combination of X-ray spectroscopies and LPM is the ideal answer to many problems in nanosciences.

The combination of XAS and scanning near-field optical microscopy (SNOM) as a local detector was proposed by Purans et.al. [2,3]. We have started with three types of experiments: (i) XAS-AFM: X-ray excited secondary electrons detection by conductive tip in AFM mode; (ii) XAS-SNOM: X-ray excited optical luminescence (XEOL) detection by SNOM in AFM mode; (iii) XAS-SCM/AFM: X-ray excited capacitance or/and photoconductivity of sample detection by conductive tip in SCM, KFM or AFM mode. The new instrumentation developed within this project offers the possibility to carry out a selective structural analysis of the sample surface with the subwavelength spatial resolution determined by the SNOM probe aperture. The apex of the optical fibre plays the role of a topographic probe, and chemical and topographic mappings can be simultaneously recorded.

References

1. J. Purans, N. D.Afify, G.Dalba, R.Grisenti, S.De Panfilis, A.Kuzmin, V.I.Ozhogin, F.Rocca, A.Sanson, S. I. Tiutiunnikov, P.Fornasini, Phys. Rev. Lett. 100, 055901 (2008)

2. J. Purans, Proc. TXRF2003 Sat. meeting on micro X-ray beam analysis, 13.09.2003, Osaka, Japan

3. S. Larcheri, F. Rocca, F. Jandard, D. Pailharey, R. Graziola, A. Kuzmin and J. Purans, Rev. Sci. Instrum. 79 013702 (2008)

Invitation : Igor Ozerov - Entrée libre