Project: Simultaneous imaging of surface topography and chemical composition under focussed X-rays irradiation.

Analytical tools offering elemental and chemical resolution at 10 nm scale are indispensable for life and physical sciences. Scanning Probe Microscopes (Scanning Tunnelling Microscopes (STM), Atomic Force Microscopes (AFM), Shear Force Microscopes…) are powerful tools for surface topography analysis at high lateral resolution, allowing to reach in the case of AFM or STM the ultimate limit of atomic resolution. However, these equipments suffer of the fact that they cannot provide chemical mapping of the analysed surface. _x000D_X-Ray Spectroscopies are ‘fine’ surface analysis techniques allowing to define chemical and structural properties of a material as well as atomic environment of a molecule and its bond lengths. These techniques are based on the spectroscopy of photons (X or visible) or photoelectrons, emitted by a surface irradiated by an X-Ray beam in far field (FF) conditions. Owing to the signal (FF) analysed, we can consider several techniques :_x000D__x000D_- XEOL (X-Ray Excited Optical Luminescence) : analysis of emitted visible photons_x000D_- TEY (Total Electron Yield) : collection of emitted photoelectrons_x000D_- XAFS (X-ray Absorption Fine Structure) : measurement of the transmission coefficient as a function of the X-Ray photons wavelength_x000D_- XANES (X-Ray Absorption Near Edge Spectroscopy) : measurement of the energy threshold absorption of the X-Ray beam_x000D_- XRF (X-Ray Fluorescence) : spectral analysis of X-Ray fluorescence._x000D_All these experiments require a high brightness X-Ray source and consequently synchrotron environments are used to irradiate the sample in Far Field (FF). The lateral resolution reached for chemical mapping (2D) is limited by the synchrotron-beam focusing lens in the micron range , but it is not possible to image the sample surface simultaneously with the chemical mapping. To improve the analysis resolution, we can imagine two solutions coupling X-Ray sources and proximal probes:_x000D_- A: limiting the surface analysed inside the irradiated area, using a local probe to collect in near field (NF) the selected signal (XRF, XEOL, photoelectrons). _x000D_- B: increasing the focus power of the excitation beam to irradiate the sample using capillary optics and keep on analysing the signals in far field._x000D_The combination of X-ray and SPM techniques is the ideal answer to many structural problems in nanosciences and the basics of such approach are emerging since years, only using the first “A” approach (FF excitation and NF analysis). X-TIP project ( FP6 STRP 505634-1 ) has recently demonstrated that XEOL and XANES spectra acquisition in near field are possible on a synchrotron beam line._x000D__x000D_The recent progress in X rays focussing optics suggest that it could be now possible to use these collimating devices in two ways:_x000D_- to irradiate locally a sample at high X-ray fluence on a spot size of less than10 µm using polycapillaries as focusing lens. _x000D_- to illuminate the sample on a spot size of 50 to 200 nm using single-capillaries positioned in the vicinity of the surface._x000D__x000D_The general idea of this project is to develop an "on table apparatus" to characterize simultaneously surface topography (lateral resolution better than 10 nm) and chemical mapping (resolution of 50 nm expected). This equipment will be based on the association of poly- or single- capillaries to drive X-rays; it will work in FF excitation / NF analysis mode. _x000D_The "light" signal emitted by the sample will be collected by a shear force regulated probe (tapered optical fiber) and analysed through a filter customized for the required application ( ie: selection of the wavelength of the luminescence band for a given element)._x000D_User friendly sample analysis at this scale is a useful goal for many industries needing quality controls in their fabrication process (i.e.: nano and micro electronics industries, space applications, life sciences, smart material analysis...)._x000D__x000D_The full set up, aim of this project will consist in :_x000D_- A small size X-ray source focused with a capillary optics ; various sources and polycapillaries are available on the market, but depending on the geometry requirements of the shear force probe, customized sources and single capillaries are to be considered. _x000D_- A shear force head : quartz tuning fork, tapered fiber, control electronics specially customized for the project._x000D_- A detection system for the optical signal : spectrometer or filters and photomultiplier tube , electronic converter for simultaneous imaging (topography/optical signal)._x000D_- A scannning sample holder : in our case scanning by the sample is necessary to keep the beam on the studied part._x000D_This set up can be considered as an extention of any SPM apparatus. We plan to use in this project a commercial contoller to drive it._x000D__x000D_The project consortium is constituted of four Ps, three R&D performing SMEs: AXESS TECH ( FR) ,LOVALITE (FR) , IFG (GE) offering complementary expertises in SPM, optical fibers , Xrays focusing, and a public laboratory CINaM (FR)._x000D_

Acronym LUMIX (Reference Number: 4383)
Duration 01/04/2009 - 31/03/2012
Project Topic We propose to focuse an Xray excitation beam using capillary optics and to collect the signal emitted by the sample in near field conditions through a tapered optical fiber. A lateral resolution of 50nm is expected for both images (topography and light) in this extention of any existing SPM .
Project Results
(after finalisation)
The CO goal of the project has been reached, two prototypes of SNOM (One already fully operational for Laboratory and a "rough one" for Industry , with necessary ergonomics changes) have been produced. For the other hand the faisability of X-rays collection through a capillary (playing the role of probe) has been demonstrated.
Network Eurostars
Call Eurostars Cut-Off 1

Project partner

Number Name Role Country
4 IfG Institute for Scientific Instruments GmbH Partner Germany
4 Centre Interdisciplinaire de Nanosciences de Marseille (CNRS Laboratory) Partner France
4 LOVALITE SAS Partner France
4 AXESS TECH SARL Coordinator France