9th International Conference on X-Ray Microscopy Journal of Physics: Conference Series 186 (2009) 012014
IOP Publishing doi:10.1088/1742-6596/186/1/012014
Fluorescence X-ray micro-spectroscopy activities at ESRF M Salomé1, P Bleuet1, S Bohic2,1, J Cauzid3,1, E Chalmin1, P Cloetens1, M Cotte4,1, V De Andrade1, G Martinez-Criado1, S Petitgirard1,5, M Rak1, J A Sans Tresserras1, J Szlachetko6,1, R Tucoulou1 and J Susini1 1
European Synchrotron Radiation Facility, X-ray Imaging Group, BP 220, F-38043 Grenoble Cedex, France 2 INSERM U-836, Institut des Neurosciences Grenoble, Université Joseph Fourier UMR-S 836, F-38042 Grenoble, France 3 CREGU & UMR G2R 7566, Université Poincaré, BP 23, F-54506 Vandoeuvre-LesNancy Cedex, France 4 Centre de Recherche et de Restauration des Musées de France, CNRS-UMR 171, Palais du Louvre, 14, quai François Mitterrand, F-7501 Paris, France 5 Laboratoire des Sciences de la Terre, Ecole Normale Supérieure de Lyon, Lyon F69007, France 6 Institute of Physics, Jan Kochanowski University, 25-406 Kielce, Poland E-mail:
[email protected] Abstract. The X-ray Microscopy and Micro-analysis beamlines at ESRF operate complementary state-of-the-art instruments at ID21, ID22, ID18F and more recently ID22NI. Within a multi-modal strategy, these beamlines develop micro-imaging techniques with various contrast mechanisms (µXRF, µXANES, µXRD and phase contrast) and host experiments with scientific topics ranging from Geochemistry to Archeology, Environmental sciences, Biology and Material sciences. Future challenges include pushing spatial resolution down to the nano-scale and the development of innovative 3D micro-analysis techniques.
1. Introduction The X-ray Microscopy and Micro-analysis beamlines of the European Synchrotron Radiation Facility form a very complete platform to investigate samples at the micro- and nano-scale with different imaging modalities. ID21 is dedicated to scanning micro-spectroscopy (µXANES) in transmission and fluorescence modes in the “low” energy range between 2 and 7.2 keV [1]. ID22 covers the complementary “high” energy range from 6 keV to 30 keV [2] and proposes a large panel of imaging techniques, combining X-ray micro-fluorescence (µXRF), micro-spectroscopy, micro-diffraction (µXRD), 3D micro-tomography and X-ray Excited Optical Luminescence (XEOL) [3]. ID22 is also extremely modular in terms of controlled sample environments. The ID18f end-station which has been developed in collaboration with MITAC (University of Antwerp, Belgium) is dedicated to µXRF and µXRD at fixed energy [4]. A pilot project towards nano-scale imaging is presently under development at ID22NI. Last, the platform includes a Fourier Transform Infra-Red (SR-FTIR) microscope located at ID21 and providing complementary molecular information on the samples. The combination of all these techniques accessible in a coordinated platform is a clear asset for the correlative investigation of complex heterogeneous samples. A typical example is the analysis of ancient paintings using c 2009 IOP Publishing Ltd
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9th International Conference on X-Ray Microscopy Journal of Physics: Conference Series 186 (2009) 012014
IOP Publishing doi:10.1088/1742-6596/186/1/012014
µXRF/µXANES/µXRD and SR-FTIR for the characterization of the mineral phases and organic binders respectively [5]. Examples of recently published experiments can be found in the following references related to scientific applications like Archeometry [6], Earth and Planetary sciences [7][8][9][10][11] or Environment sciences [12][13]. This paper will focus more on the major technical developments undertaken since the last XRM conference. 2. A new SXM at ID21 The ID21 Scanning X-ray Microscope (SXM) has recently been refurbished to include enhanced functionalities. Zone plates (ZonePlates Ltd, UK) are used as focusing optics and a typical spot size of 0.3x0.7µm2 with a photon flux of 108 -109 photons/s is routinely achieved in the 2-7 keV range. The optics stage has been fully redesigned to improve the guiding accuracy of the ZP along the optical axis, which is essential to ensure micro-beam stability during µXANES scans. A Kirkpatrick-Baez system (KB) based on elliptically shaped fixed-focus Ni coated mirrors is presently under construction for the SXM. The design of this KB is very compact due to mechanical/thermal stability requirements as well as to ensure a short focal length for efficient source demagnification. Advantages of the KB configuration will be a higher photon flux (a gain x30 is expected) and achromaticity which is preferable for µXANES. The modular optics stage can accommodate either the ZP or KB configuration. The SXM is now equipped with a HpGe 7-element fluorescence detector (Princeton Gamma-Tech, US), which offers an increased solid angle for an optimized fluorescence photons collection. A load-lock system allows faster exchange of sample under vacuum, and will greatly facilitate operation under cryogenic conditions. Control of the SXM is now performed through a fully integrated graphical user interface (GUI) developed by the ESRF Beamline Instrumentation Software Support (BLISS) Group. This GUI includes on-line visualization of the sample through a videomicroscope and direct grabbing of regions to be scanned from the video images. XRF data analysis is also facilitated by the development at ESRF of the freely distributable PyMca package [14], which batch processing capabilities allow for treatment of large data sets to produce elemental maps. All these developments contribute to a convenient operation by external users. 3. Towards nano-probes: the ID22 Nano-imaging end-station Development of hard X-ray nano-probes not only requires outstanding quality optics, but also high precision mechanics and ultimate control of many environmental parameters (e.g. temperature, hygrometry, vibrations…). In this context, the ID22NI nano-imaging project aims at deepening our expertise in all instrumental aspects related to hard X-ray nano-probes in view of the future nanofocussing activities within the ESRF Upgrade Programme. ID22NI is dedicated to 3D imaging with a target routine spatial resolution of the order of 50nm. The microscope combines different imaging schemes to provide both high resolution morphological information in Projection X-ray Microscopy mode and fluorescence micro-analysis in Scanning X-ray Microscopy mode. The instrument is located on the ID22 high-β section. A secondary source is created using high heat-load slits to increase the transverse coherence of the source. The microscope is operated in pink beam. Multilayer coated mirrors in Kirkpatrick-Baez geometry are used as focusing optics [15]. The multilayer coating increases the numerical aperture and beam flux, and is acting as a monochromator with an energy bandwidth compatible with fluorescence and projection imaging. The smallest focus achieved so far at 17keV exhibits a full width half maximum of 76x84nm2 (VxH) with a photon flux of 6x109 photons/s. A higher beam flux of 1012 photons/s in a slightly larger spot size of 100x150nm2 can be achieved by increasing the slits opening. This spatial resolution in the hard energy range opens up new possibilities in biology and more particularly for the mapping of trace metals at sub-cellular level, as illustrated by the 2D fluorescence imaging of iron distribution in neuron cells performed at ID22NI [16]. 4. From 2D to 3D A natural evolution of XRF elemental mapping is the extension towards in-depth third dimension. Compared to standard X-ray absorption tomography, fluorescence tomography is more challenging
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9th International Conference on X-Ray Microscopy Journal of Physics: Conference Series 186 (2009) 012014
IOP Publishing doi:10.1088/1742-6596/186/1/012014
since it is limited by self-absorption and matrix effects. Two strategies have been developed to overcome these physical limitations. The first strategy, pioneered at ID18f by the MITAC group (University of Antwerp, Belgium), consists of a geometrical solution, called confocal, and is based on the use of two lens optics, focusing the X-ray beam and restricting the detector angular acceptance to a small volume [17]. The intersection of the coinciding focii determines the analyzed volume in the sample. The second approach, developed at ID22, is algorithmic and relies on the combination of several signals (transmission, fluorescence and Compton) to derive the 3D distribution of elements from a pencil-beam tomographic scan [18]. The latter technique has recently been extended with the possibility to acquire simultaneously X-ray diffraction data and reconstruct a 3D map of the crystalline phases in a sample [19]. Acknowledgments The authors would like to acknowledge the outstanding support provided by the beamline technical staff, S. Labouré, F. DiChiaro, O. Beraldin and the involvement of our collaborators from the ESRF support groups R. Baker, R. Barrett, G. Berruyer, Y. Dabin, E. Gagliardini, C. Guilloud, O. Hignette, R. Hino, J.C. Labiche, A. Solé, M. Soulier and H.P. Van Der Kleij. References [1] Susini J, Salomé M, Fayard B, Ortega R and Kaulich B 2002 Surf. Rev. Lett. 9 203 [2] Somogyi A, Tucoulou R, Martínez-Criado G, Homs A, Cauzid J, Bleuet P, Bohic S, Simionovici A 2005 J. Synchrotron Radiat. 12 208 [3] Martínez-Criado G, Alén B, Homs A, Somogyi A, Miskys C, Susini J, Pereira-Lachataignerais J and Martínez-Pastor J 2006 Appl. Phys. Lett. 89 221913-1-221913-3 [4] Somogyi A, Drakopoulos M, Vincze L, Vekemans B, Camerani C, Janssens K, Snigirev A, Adams F 2001 X-ray spectrometry 30(4) 242 [5] Cotte M, Susini J, Solé V A, Taniguchi Y, Chillida J, Checroun E, Walter P 2008 Journal of Analytical Atomic Spectrometry 23 820 [6] Cotte M, Susini J, Metrich N, Moscato A, Gratziu C, Bertagnini A and Pagano M 2006 Anal. Chem. 78 7484 [7] Cauzid J, Philippot P, Bleuet P, Simionovici A, Somogyi A and Golosio B 2007 Spectrochim. Acta B 62 799 [8] Ménez B, Rommevaux-Jestin C, Salomé M, Wang Y, Philippot P, Bonneville A and Gérard E 2007 Chem. Geol. 240, 182 [9] Lemelle L, Labrot P, Salomé M, Simionovici A, Viso M and Westall F 2008 Organic Geochemistry 39 188 [10] Flynn G J et al 2006 Science 314 1731 [11] Bleuet P, Simionovici A, Lemelle L, Ferroir T, Cloetens P, Tucoulou R and Susini J 2008 Appl. Phys. Lett. 92 213111-1 [12] Isaure MP, Fayard B, Sarret G, Pairis S and Bourguignon J 2006 Spectrochim. Acta B 61 1242 [13] Prietzel J, Thieme J, Salomé M and Knicker H 2007 Soil Biology and Biochemistry 39 877 [14] Solé V A, Papillon E, Cotte M, Walter Ph and Susini J 2007 Spectrochim. Acta B 62(1):63 [15] Hignette O, Cloetens P, Rostaing G, Bernard P and Morawe C 2005 Rev. Sci. Instrum. 76 063709 [16] Ortega R , Cloetens P, Devès G, Carmona A and Bohic S 2007 Plos ONE 2(9):e925 doi:10.1371/journal.pone.0000925 [17] Vincze L, Vekemans B, Brenker F E, Falkenberg G, Rickers K, Somogyi A, Kersten M, Adams F 2004 Anal. Chem. 76(22) 6786 [18] Golosio B, Somogyi A, Simionovici A, Bleuet P, Susini J, Lemelle L 2004 Appl. Phys. Lett. 84(12) 2199 [19] Bleuet P, Welcomme E, Dooryhée E, Susini J, Hodeau JL and Walter P 2008 Nature Mater. 7 468
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