Inquiry number

INS-0000001471

XAFS

  The instruments of XAFS measurement including X-ray absorption measurements in transmission and fluorescence modes were set in the experimental hutch. The standard XAFS measurement is a transmission mode using ionization chambers (Fig.1). Three lengths of the ionization chambers, i.e., 65, 170 and 310 mm, were prepared. A current of the ionization chamber is amplified to a voltage, converted to frequency, and counted. For the gas-flow type ionization chambers, four kinds of gas, i.e., helium, nitrogen, argon, and krypton, and their mixture gas were prepared. For the fluorescence XAFS measurement, a Lytle type detector, a germanium single-element solid state detector (Ge SSD), and silicon drift-chamber detector (SDD) were prepared. The Lytle type detector has an aluminum solar slit and a 50-mm-long ionization chamber. The element of the Ge SSD has an effective area of 200 mm² and a thickness of 10 mm enabling to detect more than 95% incident X-rays. The element of the SDD has an effective area of 5 mm² and a thickness of 0.3 mm. The SDD can be operated without liquid nitrogen. A pulse motor driven XZ stage was prepared for sample position adjustment. The step is 0.002 mm per pulse for both axes. A θ - 2θ stage was mounted on the XZ stage for XAFS measurements under a low glancing angle arrangement. The step is 0.0002 degrees per pulse for both axes. X-ray optics is controlled with a personal computer through a beamline workstation. The measurement facilities in the first experimental hutch are also controlled with this computer.

Fig.1. The standard XAFS measurement is a transmission mode using ionization chambers.