Techniques and Resources

• Sample holders for 8 and 13 mm diameter pellets.
• Cells for liquid samples.
• Capillary holders.
  
• Pulse tube He cryostat for transmission and fluorescence XAS measurements: 6 to 300K.
  
• LN2 cryojet for measurements with capillaries: 90 - 300K.
• LN2 cryostat for XAS transmission and fluorescence measurements: 77 to 300K.
• Stinger He closed system vacuum cryostat for XES down to about 6K, (up to 3 samples in chamber : sample exchange ca 12 hrs, samples must be mounted at RT.)
• Linkam stage for XES and XAS: 90K to 870K.
• Plug flow reactor for transmission, fluorescence and XES: up to 1100K; Kapton and Quartz tubes.
• Portable gas delivery system.
• Mass Spectrometer.
• Halogen lamp furnace: up to 1200K.
• Stopped flow system.

 

• Ionisation chambers for transmission measurements (He, N2, Ar, Kr gases).
• 64 element monolithic Ge detector with Xspress4 for XAS fluorescence measurements.
• Four element Si-drift detectors for XAS fluorescence measurements.
• Four and one element Medipix detectors for XES measurements.

Xspress4

The new Digital Pulse Processor, Xspress4, developed at Diamond Light Source [1] employs a novel event cross-talk correction algorithm to allow a significant increase in detector count rate of the 64-element Ge detector for the equivalent MCA spectral performance of Xspress2. The improved resolution attained with Xspress4 allows more dilute and complex samples to be measured in fluorescence mode as we can operate the 64-element fluorescence detector to the Output Count Rate (OCR) of 600 to 800 KHz per element, instead of apporx. 250 kHz with Xspress2.

X-ray Absorption spectrum collected from 43ppm yttrium standard sample (GSD11) using the Xspress4 system on Beamline I20: merger of 4 consecutive XAS spectra together taken with Xspress4 and Xspress 2; MCA spectra taken with  Xspress4, showing that the fluorescence line of interest Y Ka is well resolved with Xspress4, thanks to the improved MCA resolution at approx. 630 kHz OCR per element.

 

Above shows a) a merge of 10 spectra XAS spectra and b) extracted EXFS signal taken using the 64-element Ge detector with the Xspress4 pulse processor system. The spectra were collected from a contaminated sediment containing 80ppm Hg in the in-house LN2 cryostat with the sample-detector distance adjusted to give the OCR of apporx. 600 kHz (Sam Shaw et al., University of Manchester).  

 

[1] G. Dennis, W. Helsby, D. Omar, I .Horswell, N .Tartoni, S. Hayama, I. Mikulska, and S .Diaz-Moreno. SRI2018 proceedings.

 

 

• UV-Vis spectroscopy: 300 - 1150 nm.
• Fibre-optic Raman spectrometer: two lasers 532 and 735nm fitted with 600 and 1800 gratings.