X-ray Fluorescence Analysis A.Somogyi (ESRF) A.Iida (KEK-PF) K.Sakurai (NIMS, Tsukuba) T. Ohta (U.Tokyo)

What happens by core hole creation? K L M X-ray Fluorescence K L M Auger electron emission

How can we create core holes? X-rays, Electrons, Ions which have higher energy than the core electron ionization energies. Electrons and ions produces many peaks with multiple excitations. X-ray excitation is preferable. Now, X-ray fluorescence analysis by X-ray excitation is a standard technique for trace element alalysis.

How is the Trace Characterization important? Bio-medical ? Social ? Industrial LSI Environmental ?

Why synchrotron radiation x- rays ? Higher intensity  higher sensitivity Energy tunability  Make the analysis easier, chemical state analysis Polarizablity  Reduce background Directionality  applicable to tiny sample  Spectromicroscopy, Imaging

Synchrotron Radiation excited X-ray fluorescence Analysis High sensitivity ng=>fg, ppm=>ppb Chemical state analysis Micro-beam analysis mm=>  m Total reflection analysis atoms/cm 2 =>10 8 atoms/cm 2 Non-destructivemulti-elemental analysis environmental conditionhigh accuracy wide dynamic range Advantages of XRF elemental analysis SR

Si ( Li ) Detector Sample Critical Angle Total-refection X-Ray Fluorescence ( TXRF ) Reduction of scattering background from the substrate(1)

Detector R SR (horizontally polarized beam) ISIS IFIF  r Total-refection X-Ray Fluorescence ( TXRF ) Reduction of scattering background from the substrate (2) Fluorescent X-rays Scattered X-rays

Sample: chelete resin beads Monochromatic excitation Laboratory source Continuum excitation Refl./Trans. Mirrors Comparison of S/N and S/B ratios

How to analyze X-Ray Fluorescence Wavelength-dispersive vs. energy-dispersive Wavelength-dispersive solar-slit crystal gas/scintillation detector Energy 2dsin  = Energy-dispersive electronic signal processing MCA Energy semiconductor/ superconductor detector

 Qualitative and quantitative analysis  in terms of XRF  Intensity changes  Chemical shifts  Profile changes and other fine structures  Satellite lines Double-crystal spectrometer Single-crystal spectrometer Si ( Li ) detector Chemical Characterization by X-ray Fluorescence Spectra

Intensity ( normal ised ) Energy ( eV ) ( eV ) KMnO 4 K 2 MnO 4 Mn green MnO 2 Mn 2 O 3 MnO MnK   MnK   Chemical Shifts and Profile Changes High resolution X-ray spectrometry Prof. Y. Gohshi

Fe 2 O 3 FeO EHEH ELEL Selectively Induced X-Ray Emission Using Edge Shifts Use of tunable monochromatic synchrotron source K.Sakurai ~1988

Kirkpatrick-Baez Optics sample SR Slit 1 Double crystal monochromator Multilayer monochromator Slit 2 side view top view IC sample Synchrotron X-Ray Microbeam Beam size 5~6  m 2 (1  m min) Photon Flux(Max) (Multilayer) 10 8 (DXM)

Application to criminology A serious case of murder happened in a small town in Japan in White arsenic(arsenic oxide) was mixed in curry and 5 kids died of arsenic poisoning. No wittness and no confession, only presumptive evidence XFS technique works effectively.

XFS of white arsenic produced in various countries Sb China Mexico X-ray energy(keV) As Ag Sb Bi Korea Spectral patterns from two samples agree with each other!

Plan View of Beamline 40XU at SPring-8 Experimental hutch Optics hutch K-B mirrors Spectrometer HALL RING SR ID Gap 12mm S S N N Helical Undulator 40m45m50m 55m (Distance from the source) 35m

From Energy-dispersive to Wavelength-dispersive Spectrometer To further upgrade signal to background ratio Energy-dispersive TXRF Sample Si(Li) Detector Substrate X-ray Wavelength-dispersive TXRF Large solid angle (High detection efficiency) Collecting whole XRF spectra simultaneously Large solid angle (High detection efficiency) Collecting whole XRF spectra simultaneously Low energy-resolution Limitation of counting-rate Scattering background Low energy-resolution Limitation of counting-rate Scattering background Advantages Disadvantages High energy-resolution Good signal to background ratio High energy-resolution Good signal to background ratio Advantages Low detection-efficiency Disadvantages Analyzing Crystal (Johansson) Sample Substrate X-ray Scintillator detector

Design Considerations Flexibility and feasibility for practical analytical applications Detector SR Entrance Slit Curved Crystal Johansson Ge (220) Receiving Slit Sample Rowland Circle R=120mm ( flexible ) Rowland Circle R=120mm ( flexible ) Vac. chamber 4 axes for scanning X-ray energy 4 axes for alignment and positioning of the sample

Compact Johansson X-ray Fluorescence Spectrometer Detector Ionization chamber SR Crystal analyzer Ge (220) Johansson He gas Sample Sample positioning stages Vac. chamber

Performance of the Spectrometer Feasibility for the analysis of trace elements in small samples 100  m Glass Capirally Lily Pollen (20 particles.) (300 ppm) (5800 ppm) Coal Fly Ash (NIST SRM-2690) (67 ppm) Capillary Powders adhered to glue sphere (~0.5mm) 35mm FWHM 7.2eV

Substrate X-ray Sample Fe, Ni, Co 20ppb 0.1  l FWHM 5.71eV FWHM 5.71eV FWHM 6.62eV FWHM 6.62eV FWHM 7.06eV FWHM 7.06eV 5 sec/point WD-TXRF Spectra for Trace Elements in Micro Drop Significant enhancement of signal to background ratio

Performance of Wavelength-Dispersive TXRF ppt level detection limit with less than 10eV energy Concentration of solution of 0.1  l Detection Limit Ni Absolute amount 0.31fg3.1ppt Ni in 0.1  l solution 13536counts /20sec 196counts /20sec Ni 1ppb-0.1  l liquid drop FWHM 7eV Calibration curve

Summary Towards ppt chemistry Concentration ( g/g ) AAS ICP-MS Conventional XRF Conventional XRF Conventional TXRF Conventional TXRF (pg) (  g) (ng) (fg) (ppt) (ppb) (ppm) Absolute amount ( g ) Trace chemical characterization using K  spectra Reducing scattering background as well as parasitic X-rays due to contamination is extremely important. Downsized wavelength depressive XRF spectrometer is effective to enhance both detection efficiency and energy resolution. Present detection limit (SR-WD TXRF) ~ g ~ (ppt) For 0.1  l

Conclusions SR-X-ray XRF technique is very powerful. Low detection limit down to fg, ppt level applicable to samples of limited size well analyzed due to energy tunability and high energy resolution Development of XRF imaging Combination with different micro techniques (XRD, XANES and EXAFS)