Preliminary optical design of a varied line-space spectrograph for the multichannel detection of Near-Edge X-ray Absorption Fine Structure (NEXAFS) spectra in the 280- to 550-eV energy range

摘要

Abstract: The optical design of a varied line-space spectrograph for the multi-channel recording of NEXAFS spectra in a single `snapshot' is proposed. The spectrograph is to be used with a bending magnet source on beamline 7.3.2 at the Advanced Light Source. Approximately 20 volts of spectra are simultaneously imaged across a small square of material sample at each respective K absorption edge of carbon, nitrogen, and oxygen. Photoelectrons emitted from the material sample will be collected by an electron imaging microscope, the view field of which determines the sampling size. The sample also forms the exit slit of the optical system. This dispersive method of NEXAFS data acquisition is three to four orders of magnitude faster than the conventional method of taking data point-to-point using scanning of the grating. The proposed design is presented along with the design method and supporting SHADOW raytrace analysis.!24