Precision x-ray spectroscopy in high orders of reflection

The full width at half maximum intensity (linewidth) of x-ray K~ lines of copper and iron in high orders of Bragg reflection have b~en studied with a spherically bent mica crystal spectrometer. From the results of. these experiments, it has been qualitatively established for the first time that the linewidth of x-rays decreases as the order of reflection increases. Results for the 7th through lOth order reflections of the iron K~ 1 and K~ 2 lines and. the 9th through 12th order reflections of copper K~ 1 and K~ 2 lines are discussed. The separation of the KS 1 ,3 lines of iron has also been measured with the same instrument. The linewidths of copper K~ 1 and K~ 2 lines in 12th order of Bragg reflection were investigated with the same spherically bent crystal but with a microfocus x-ray tube which produces an x-ray source of 30 micron in diameter point focus. The x-ray source is placed on the Rowland circle of the spectrometer.