LAUSR

A scanning transmission x-ray microscope (STXM) has been operational from 2014 at the 10A beamline of the Pohang Light Source (PLS). Schematic of the STXM in normal operation mode (absorbance-change detection mode) is shown in Fig. 1(a) and a photo showing details near the sample is in Fig. 2(a). The optical components including sample stage are mounted inside a vacuum chamber (10 mbar base pressure). The incident photon flux into the STXM chamber is shown in Fig. 1(b), and practically usable photon energy range for STXM is from ~150 eV to ~1600 eV. Spectral resolving power, E/E, of the xrays is ~5000 below 1000 eV, which allows us to resolve energy level position and occupation changes, or detailed spectral changes for understanding the sample’s chemical states, unoccupied electronic density of states, and/or crystal structure. As an x-ray source, 72 mm period elliptically polarized undulator (EPU) is used allowing us to control helicity of x-rays for understanding magnetic domain structure and dynamics by employing x-ray magnetic circular dichroism technique. Distance from the virtual source (Exit slit) to the zone plate (ZP) is 2.5 m. The virtual source size is typically about or less than 10 m and thus the demagnified virtual source size is generally smaller than the diffraction limited spot size; with 25 nm outermost zone wide (rn) ZP, the diffraction limited resolution, 1.22rn ~ 30 nm, is achieved upto ~1000 eV. 25, 40, and 60 nm ZPs are equipped for experiments. Details of normal operation mode functionality of the STXM are recently reported [1]. The STXM has been applied to transition metal doped ZnO nanoparticle catalysts [2], bio-specimen in dry condition or under wet condition [3], FeOx nanoparticle effects on bio-specimen, domain structure of magnetic thin films [4], secondary ion battery materials, and so on.