1. Towards X-ray excited optical microscopy (XEOM) for cultural heritage, spectroelectrochemistry, and wider applications Mark Dowsett 1, Annemie Adriaens 2, Gareth Jones 1 and Alice Elia 2 1 Analytical Science Projects Group, University of Warwick 2 Electrochemistry and Surface Analysis Group, Ghent University Thanks to : Paul Thompson, Simon Brown (XMaS, ESRF) Sergey Nikitenko (DUBBLE, ESRF), Nigel Poolton (Formerly SRS, Daresbury) Analytical Science Projects

2. Goal: Develop XEOL microscope coupled to an environmental cell for synchrotron applications Real time process monitoring in controlled electrochemical and gaseous ambients – corrosion and protection studies Ultimate goal: Develop a portable version for direct chemical imaging in museums etc. Microscopy of the chemical state rather than just elemental composition (i.e. A step beyond portable XRF)

3. Why XEOL? Based on transoptical emission (200-1000 nm) caused by keV X-ray irradiation - phosphorescence, fluorescence Electronic processes responsible for XANES and EXAFS impose similar structure on the light emission Extra band specific-features due to excitation of chromophores by LE electron scattering Spectra are (at least) two dimensional – X-ray energy and emitted optical wavelength Technique has a high surface specificity – sees thin layers on surfaces invisible to conventional XAS Basis of a chemically specific optical microscopy - image formation using broadband light optics

4. A surface or transmission microscopy tool e-e-

5. Proof of concept - ODXAS 1 Broadband PM Shutter Optical bench Filter housing Web cam (1 of 2) X-ray port 1 eCell Ref. electrode Stepper 1 Stepper 2 X-ray port 2 X-ray detector Illumination Optics

6. sample piston window Silica objective Filter Silica condenser

9. XAS (DUBBLE) XAS (DUBBLE) XEOL (XMaS) Copper – XAS and XEOL-XAS XAS (DUBBLE) XEOL (XMaS) Parallel XAS (XMaS)

10. Nantokite on copper – XEOL surface specificity (XEOL)

11. Cuprite (Cu 2 0) – XAS and XEOL-XAS Comparison Dowsett, Adriaens, Jones, Fiddy, Nikitenko, Anal. Chem. 80 (2008) 8717-8724

12. Materials of construction... e.g. The eCell window... and the rest... eCell body X-ray shielding Optical column Substrate (for Powders etc.) (13 keV X-rays)

13. Other edges (so far) Zn (K) Pb (LIII) Clean metal Lead decanoate 1.8 eV Pb (LIII)

14. Colour filters Nantokite (CuCl) on copper Atacamite (Cu 2 (OH) 3 Cl) on copper

15. Thick layer on copper “Fine dusting” on acetal Through green filter Identifying mixtures with filters

16. Potential imaging modes Time to a mean 3% precision per pixel in broadband image < 1000 s for 2048 x 2048 pixels Filtered images Near edge image spectra Dispersed images Edge correlated images (form image on correlation with specific oxidation state etc. EXAFS image spectra – given time

17. Next steps Filters (imaging mode) Filtered (imaging) or broadband (spectroscopy) Schematic diagram of XEOM 1 - Imaging Broadband CCD 2, 2048 x 2048 Sample X-rays Objective optics Broadband optical emission Image Focusing condenser

18. Next steps Schematic diagram of XEOM 1 - Spectroscopy Sample X-rays Objective optics Broadband optical emission Grating Projection optics Broadband CCD 1, 500 x 2048 Spectrum/Image spectrum Focusing condenser

19. Summary and Conclusions XEOL provides multispectral information including XANES and EXAFS from heritage metals and corrosion products Optical devices with constructed with broadband optics will provide microscopy with (light) wavelength limited resolution Suitable for beam lines with large (millimetres ) footprint XEOM has potential applications in Measurements in controlled environments Metal corrosion research Geosciences Semiconductor research Organo-metallics... Silica lens – based microscope –> mid to end 2010 Mirror-based device -> 2011-2012 Portable device ?