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BL 11.0.2 Scanning Transmission X-ray Microscopy (STXM) Mini-Workshop Wednesday, 23 July 2003

BL 11.0.2 Scanning Transmission X-ray Microscopy (STXM) Mini-Workshop Wednesday, 23 July 2003. Itinerary. 10:00 AM Beamline 11.0.2 Properties Relevant to STXM 10:15 AM Principles of STXM ("How the STXM Works") 10:45 AM Sample Preparation and STXM Capabilities

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BL 11.0.2 Scanning Transmission X-ray Microscopy (STXM) Mini-Workshop Wednesday, 23 July 2003

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  1. BL 11.0.2 Scanning Transmission X-ray Microscopy (STXM) Mini-WorkshopWednesday, 23 July 2003

  2. Itinerary 10:00 AM Beamline 11.0.2 Properties Relevant to STXM 10:15 AM Principles of STXM ("How the STXM Works") 10:45 AM Sample Preparation and STXM Capabilities 11:30 AM STXM Hardware and Software at Beamline 11.0.2 12:00 PM Lunch Provided in Building 2-100B 1:00 PM Data Collection Examples and Strategies 2:00 PM Processing STXM Data 2:30 PM Data Collection from a "Real Sample"

  3. Beamline 11.0.2

  4. Monochromator • No entrance slit • PGM - variable included angle • 2 gratings – 150 l/mm, 1200 l/mm • 85 eV -1900 eV Cff = cosb/cosa Recommended Cff = 2 for 1200 l/mm Cff = 1.6 for 150 l/mm

  5. Refocusing mirrors

  6. Exit slits • Dispersive – vertical (12 mm min) • Non dispersive – horizontal (35 mm min)

  7. Photon shutter

  8. STXM vacuum valve

  9. Photon Flux Note: Jan 12, 2004 These are not the most current flux measurements (300 mA)

  10. Si3N4 window zone plate (Au on Si3N4) scanned sample detector x-ray OSA STXM interior schematic He, air or vacuum Manual for STXM 5.3.2 http://www-als.lbl.gov/als/techspecs/STXM532-manual.pdf

  11. OSA (z=0) sample holder Zone Plate (ZP) sample in a wet cell Ao ZPo sample Z offset fo -ve z +ve z z=0 STXM interior distances Current zone plate: 155 mm diameter, 35nm smallest zones, 65 mm central stop Focal length 280 eV – 1100 mm, 700 eV - 3000 mm Ao (mm) = E (eV)

  12. Zone Plate The focal length (f) of a zone plate at a given photon energy (E) is given by: f = D•drN / l where D is the ZP diameter, drN is width of the most outer zone (Nth), and l is the photon wavelength (E (eV) = 12398.52/ l in Å scale). Current value of D and drN are 155 mm and 35 nm respectively. The diffracted limit spatial resolution (Dr). Dr = 1.22•drN

  13. Stages

  14. Drawing of STXM

  15. Block diagram

  16. Sample holder y x 3 holes 2.7 mm 5 mm spacing TEM Grids Single Si3N4 windows Wet cells – double Si3N4 windows Fix the sample to the sample holder

  17. Sample thickness • Absorption (OD from 0.4 to 1.5) 30%-80% absorption (OD = -ln ( I / Io) = .t = ..t ) • Adjust for resonance peak intensity Io measurements – plan for it when making a sample There is no possibility to measure Io independently

  18. Calculate sample thickness Si3N4 PMMA Fe3O4

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