[U04-P01] X線吸収分光法を利用したSPring-8における時間分解計測の現状
キーワード：X線吸収分光法、時間分解、放射光
X-ray Absorption Fine Structure (XAFS) is powerful tool to investigate electric structure and local structure around X-ray absorption atom. Time resolved XAFS measurement developed from appearance of synchrotron radiation and have been applied to many fields. For example, time-resolved XAFS is applied for the catalytic reaction at the in-situ condition and give us the information about how the chemical reaction progresses. We will introduce three representative time-resolved XAFS measurement.
(Super) Quick XAFS (QXAFS),
In QXAFS, the monochromator sweeps quickly (or oscillates at high frequency in Super QXAFS) and it measures the incident X-ray and transmission/fluorescence X-ray intensity continuously. The time resolution depends on the sweep speed of monochromator and the flux of X-ray. The fastest time-resolution of QXAFS in SPring-8 is 800 μs/spectrum which using galvano motor driven monochromator and very compact Si channel-cut crystal without cooling system.
Energy Dispersive XAFS (DXAFS)
DXAFS is a method of measuring the XAFS spectrum by one-shot acquisition. DXAFS measurement is done by converting the energy of X rays into position information using a polychromator and monitoring the position and intensity using a position sensitive detector. So DXAFS has higher time-resolution than QXAFS and the time-resolution is about few ms as usual.
Pump-probe XAFS
Pump-probe XAFS is a method that uses bunch structures of synchrotron radiation. X-ray from the synchrotron facility has a time width. For example at SPring-8, the time width of each X-ray is about 50ps and interval between each X-ray is about 100nsec. Pump-probe XAFS use such time-structure and achieve high time-resolution. However, this method can only apply for repeated reactions.
(Super) Quick XAFS (QXAFS),
In QXAFS, the monochromator sweeps quickly (or oscillates at high frequency in Super QXAFS) and it measures the incident X-ray and transmission/fluorescence X-ray intensity continuously. The time resolution depends on the sweep speed of monochromator and the flux of X-ray. The fastest time-resolution of QXAFS in SPring-8 is 800 μs/spectrum which using galvano motor driven monochromator and very compact Si channel-cut crystal without cooling system.
Energy Dispersive XAFS (DXAFS)
DXAFS is a method of measuring the XAFS spectrum by one-shot acquisition. DXAFS measurement is done by converting the energy of X rays into position information using a polychromator and monitoring the position and intensity using a position sensitive detector. So DXAFS has higher time-resolution than QXAFS and the time-resolution is about few ms as usual.
Pump-probe XAFS
Pump-probe XAFS is a method that uses bunch structures of synchrotron radiation. X-ray from the synchrotron facility has a time width. For example at SPring-8, the time width of each X-ray is about 50ps and interval between each X-ray is about 100nsec. Pump-probe XAFS use such time-structure and achieve high time-resolution. However, this method can only apply for repeated reactions.