Description
The SOLARIS National Synchrotron Radiation Centre is a 1.5 GeV 3rd generation synchrotron located in Krakow, Poland. As a low energy storage ring, this facility is going to specialize in building its beamlines mostly in the soft X-ray region. One of them is the DEMETER beamline, on which the Scanning Transmission X-ray Microscopy (STXM) is located. The beamline is a classic Plane Grating Monochromator (PGM) design with an Elliptically Polarizing Undulator (EPU) as a source and works in 100-2000 eV photon energy range. The STXM microscope has been designed and built in-house. The main goal of the design is to provide a universal microscope that can be easily reconfigured to a specific experiment. Microscope’s relatively compact chamber enables faster sample load/unload and more economical purging with pure He, when a sample cannot be subjected to vacuum.
Our STXM design is based on the Advanced Light Source (ALS) beamline 5.3.2 STXM [1] but there is a significant difference. The microscope does not have sample stages in the direction of the X-ray beam. It has the Order Sorting Aperture (OSA) motion in this direction, instead. This modification reduces sample vibration and helps in the focusing procedure. Additionally, a custom Field-Programmable Gate Array (FPGA) is used there for timing, acquisition and fast shutter control.
This STXM is operating on a modern undulator beamline, therefore acquisition time of a single-pixel can be less than 1ms, enabling fast scanning. To maintain the sample position with changing X-ray energy, we use a laser interferometer in a closed loop feedback. This STXM design is suitable for commercial electrochemical cell made by Hummingbird Scientific and also good for using a big matrix detectors for operating in ptychography mode in the future. Thanks to the use of an undulator with variable polarization, it is possible to perform measurements using the XMCD or XMLD effect for magnetic samples.
Apart of our STXM design and capability details, some example results of recent experiments will be presented.
References: [1] A. L. D. Kilcoyne, at al. (2003), J. Synchrotron Rad. 10, (125–136).