The Spectrum of X-Rays Scattered from Graphite Studied by Means of the Double Crystal Ionization Spectrometer

Citation

Hoyt, Archer (1931) The Spectrum of X-Rays Scattered from Graphite Studied by Means of the Double Crystal Ionization Spectrometer. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/82vy-yb03. https://resolver.caltech.edu/CaltechTHESIS:09102024-223402170

Abstract

The scattered spectrum of Graphite is obtained using apparatus consisting of a Hoffmann Electrometer and stationary ionization chamber, (total capacity of insulated system 12 e.s.u.) a specially designed double crystal (calcite) spectrometer, and a specially designed metal x-ray tube fitted with thin windows close to the focal spot so that scattering could be obtained from a graphite scatterer placed 5/8' from the focal spot at an angle of scattering of 165 ± 10°. The tube was operated on the vacuum pumps at 60 KV and 10 m.a. C.P.D.C.

The spectral curves obtained were reproducible and in good agreement with the best work in the field and the following conclusions can be drawn from them. (1) The Compton modified line M_OK∝1,2 scattered from graphite at 165° ± 10° scattering angle is very broad - of the order of 21 X.U. at half maximum height. (2) On account of this excessive breadth there is no discernible separation of the ∝ doublet in the modified spectrum. (3) No fine structure exists in the scattered spectrum of intensity > 1/5 of the intensity of the modified radiation. (4) The ratio of intensity of the modified to unmodified scattered radiation determined by measuring the areas under the spectral curves was found to be 7.3 : 1. (5) Viewed in the light of the theory of DuMond for the dependence of modified line breadth on scattering angle, the great breadth of the observed modified line can be interpreted as direct experimental evidence of a dynamic atom. (6) There appears to be no essential difference in the results obtained, whether a spectrum is studied with the single or double crystal spectrometer except in regard to resolution.

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