X-ray Absorption Spectra in transmission
2019-01-31, step scanning (35 min/scan), 2 repeats, Si111 crystals, room temperature
Balder (green) compared to other beamlines (blue/orange)
2019-02-08, fly scanning (1 min 24 sec/full EXAFS scan), 35 repeats (not averaged)
Fly scan (orange) compared to step scan (blue). We are currently working on fine-tuning the fly scan performance. Presently, we can scan with a total accumulation time down to ~30 sec per full EXAFS. Notice a slight decrease in the 1st FT peak height. This is a result of ‘’running average” – a convolution of the real spectra with a rectangular broadening function given by the integration time duration (presently down to 1 ms). The user will eventually have control of this broadening at the expense of total scan time and S/N ratio.
2019-03-06, fly scanning (1 min 24 sec/full EXAFS scan) on CuO pressed 13 mm pellet (2 absorption length), focused beam (~6 x 1012 photons/sec) 30 scans on fixed spot, average of 1-15 (orange) and 16-30 (blue).
Copper (II) sulfate in solution
2019-03-08, fly scanning (1 min 24 sec/full EXAFS scan) on 0.1 M CuSO4 (aq) in liquid cell with 1.5 mm path length, focused (100 µm2) versus defocused (h x v, 0.1 x 2 mm2) beam with a small step displacement before each new scan, average of 11 scans defocused (orange) and focused (blue).
Focused beam spot size with Si111 or Si311 monochromator crystals
Si111 Horizontal 100 µm, Vertical 80 µm Si311 Horizontal 90 µm, Vertical 90 µm
Experimental rocking curve (green dots) overlap with theoretical reflectivity curve for two crystals (orange).
Flux on sample 3 x 1012 photons/sec