Diamond Sensors and Polycapillary Lenses for X-ray Absorption Spectroscopy
Bruce D. Ravel
Diamond sensors are evaluated as incident beam monitors for X-ray Absorption Spectroscopy experiments. These single crystal devices pose a challenge for an energyscanning experiment using hard X-rays due to the e ect of diffraction from the crystalline sensor at energies which meet the Bragg condition. This problem is eliminated by combination with polycapillary lenses. The convergence angle of the beam exiting the lens is large compared to rocking curve widths of the diamond. A ray exiting one capillary from the lens meets the Bragg condition for any re ection at a different energy from the rays exiting adjacent capillaries. This serves to broaden each diffraction peak over a wide energy range, allowing linear measurement of incident intensity over the range of the energy scan. Extended X-ray Absorption Fine Structure data is measured with a combination of a polycapillary lens and a diamond incident beam monitor. These data are of comparable quality to data measured without a lens and with an ionization chamber monitoring the incident beam intensity.