A methodology for calibrating wavelength dependent spectral resolution for crystal spectrometers

High quality absorption spectroscopy measurements were recently achieved at the Sandia National Laboratories Z facility in the soft x-ray range. Detailed spectral resolution knowledge is a key requirement for their interpretation. We present a methodology for measuring the wavelength dependent crystal spectral resolution, with a particular focus on the 7-17 angstrom range. We apply this procedure to the case of 1st order resolution of a potassium acid phthalate (KAP) convex crystal spectrometer. One calibration issue is that inferring the crystal resolution requires that the x-ray source emission feature widths and spectral profiles are known. To this aim, we resolve Manson x-ray source Si, Al, and Mg K alpha line profiles using a KAP crystal spectrometer in 2nd order to achieve relatively high resolution. This information is exploited to measure 1st order KAP resolving powers lambda/Delta lambda similar to 1100-1300 in the 7-10 angstrom wavelength range. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4740269]