Smolentsev Grigory, Guda Alexander, Zhang Xiaoyi, Haldrup Kristoffer, Andreiadis Eugen, Chavarot-Kerlidou Murielle, Canton Sophie E, Nachtegaal Maarten, Artero Vincent, Sundstrom Villy
Lund University, Lund, 22100, Sweden ; Paul Scherrer Insitute, Villigen, 5232, Switzerland.
Research center for nanoscale structure of matter, Southern Federal University, Rostov-on-Don, 344090, Russia.
J Phys Chem C Nanomater Interfaces. 2013 Aug 29;117(34):17367-17375. doi: 10.1021/jp4010554.
A new setup for pump-flow-probe X-ray absorption spectroscopy has been implemented at the SuperXAS beamline of the Swiss Light Source. It allows recording X-ray absorption spectra with a time resolution of tens of microseconds and high detection efficiency for samples with sub-mM concentrations. A continuous wave laser is used for the photoexcitation, with the distance between laser and X-ray beams and velocity of liquid flow determining the time delay, while the focusing of both beams and the flow speed define the time resolution. This method is compared with the alternative measurement technique that utilizes a 1 kHz repetition rate laser and multiple X-ray probe pulses. Such an experiment was performed at beamline 11ID-D of the Advanced Photon Source. Advantages, limitations and potential for improvement of the pump-flow-probe setup are discussed by analyzing the photon statistics. Both methods, with Co K-edge probing were applied to the investigation of a cobaloxime-based photo-catalytic reaction. The interplay between optimizing for efficient photoexcitation and time resolution as well as the effect of sample degradation for these two setups are discussed.
一种用于泵浦-流动-探针X射线吸收光谱的新装置已在瑞士光源的SuperXAS光束线投入使用。它能够以数十微秒的时间分辨率记录X射线吸收光谱，并且对于亚毫摩尔浓度的样品具有高检测效率。使用连续波激光进行光激发，激光与X射线束之间的距离以及液体流动速度决定了时间延迟，而两束光的聚焦和流速则决定了时间分辨率。该方法与利用1 kHz重复频率激光和多个X射线探测脉冲的替代测量技术进行了比较。这样的实验是在先进光子源的11ID-D光束线进行的。通过分析光子统计数据，讨论了泵浦-流动-探针装置的优点、局限性和改进潜力。两种方法，均采用钴K边探测，被应用于基于钴肟的光催化反应的研究。讨论了这两种装置在优化高效光激发和时间分辨率之间的相互作用以及样品降解的影响。
