UVSOR National Institutes of Natural Sciences Institute for Molecular Science UVSOR Facility

BL3UVaried-Line-Spacing Plane Grating Monochromator for Molecular Soft X-Ray Spectroscopy

▼Description
  The beamline BL3U is equipped with an in-vacuum undulator composed of 50 periods of 3.8 cm period length. The emitted photons are monochromatized by the varied-line-spacing plane grating monochromator (VLS-PGM) designed for various spectroscopic investigations in the soft X-ray range. Three holographically ruled laminar profile plane gratings are designed to cover the photon energy range from 40 to 800 eV. The beamline has liquid cells for soft X-ray absorption spectroscopy (XAS) in transmission mode as shown in Fig. 1. The liquid cell is in the atmospheric helium condition, which is separated by a 100 nm thick Si3N4 membrane with the window size of 0.2 × 0.2 mm2 from the beamline in an ultrahigh vacuum condition. The thin liquid layer is assembled by using two 100 nm thick Si3N4 membranes. The thickness of the liquid layer is controllable from 20 to 2000 nm by adjusting the helium pressures around the liquid cell in order to transmit soft X-rays. Liquid samples are exchangeable in situ by using a tubing pump. The liquid cell has two types of windows: one is the liquid part to obtain the soft X-ray transmission of liquid (I), and the other is the blank part to obtain the transmission without liquid (I0). We can obtain the reliable XAS spectra based on the Lambert-Beer law ln(I0/I). Since the liquid cell is in the atmospheric condition, we can measure XAS of liquid samples in the real environment. Operando XAS observation of several chemical reactions such as catalytic, electrochemical reactions are also possible by using our liquid cells developed for these purposes.

　　　　　
  Fig. 1. Schematic layout (left) and the photography (right) of the BL3U. The distances along the beam from the center of the in-vacuum plane undulator are shown in millimeters. S1X and M2X can be replaced with the other exit slit S1 so that experiments can be carried out at either the XES or the multipurpose endstation. In the XES setup, the sample is placed 5–10 mm downstream of S1X.

▼Technical Data