A unique wavelength-dispersive soft X-ray emission spectrometer for electron probe X-ray microanalyzers

摘要

Wavelength-dispersive X-ray spectrometers have been around for more than 60 years. They have maintained a central role in microanalyses because of their effectiveness at measuring X-rays reproducibly, and because of their high spectral resolution. However, these traditional spectrometers have been limited in the ultralow energy range. A radically new WD spectrometer has now been developed that allows the measurement of ultrasoft X-rays, down to 5C eV. This allows for lithium to be measured into the tens of ppm range. This soft X-ray emission spectrometer (WD-SXES) uses an aberration-corrected, concave, variable line-spacing grating to disperse X-rays of different wavelengths. The dispersed X-rays then get projected onto a CCD array, which acts as the detector. The result is a solid-state spectrometer capable of collecting an entire spectrum simultaneously from 50 to 210 eV. However the grating is also very efficient at dispersing higher-order X-ray lines, and therefore lines up to 700 eV can be routinely measured.