A multi-purpose experimental station for soft x-ray microscopy on BACH beamline at Elettra

摘要

A new experimental station for soft x-ray microscopy is under construction at BACH beamline, at Elettra Synchrotron Radiation Facility (Italy). This station will be devoted both to scanning transmission x-ray microscopy (STXM) and photoemission microscopy (SPEM), with spatial resolution of about 50 nm. A Fresnel Zone Plate (FZP) will provide the micro-focusing of the beam delivered by the monochromator of BACH. The photon beam features are high resolving power (30000-5000 in the 40-1500 eV range), high flux (more than 10~(11) photons/s after the exit slit) and the possibility to select the light polarization. The experimental chamber will host several photon and electron detectors which should provide spatially resolved information of the bulk and surface composition. The expected acquisition times are of the order of the seconds for STXM and less than 1 minute for SPEM. The branch line hosting this station will start from the exit slit of the BACH monochromator. A toroidal mirror will focus are exit slit-spot on a pinhole which will be the source for the following FZP. With a 10 * 10 μm~2 pinhole it will be possible to obtain a spot of about 50 * 50 nm~2 with enough flux (from 10~8 to 10~9 ph/sec) to perform microscopic experiments with polarized radiation. In this paper we present the optical scheme of the instrument as well as the foreseen performances in terms of resolution and flux.