Bragg crystal reflection experiment of 1913
ID: bragg-crystal-reflection-experiment-of-1913
William Lawrence Bragg introduced the plane interpretation; his father William Henry Bragg built the X-ray spectrometer. Their joint 1913 paper, The Reflection of X-rays by Crystals, reports the experiment. [ref]
The Bragg law (University of Leeds Library Special Collections). The Bragg law: Lawrence's 1912 interpretation and the angle convention
[ref]William Bragg's spectrometer (Royal Institution collection). Description: William Henry Bragg designed and made the spectrometer
An X-ray tube supplied radiation through lead slits to a crystal mounted with its cleavage face through the rotation axis. A rotating ionization chamber replaced a spectrometer telescope; electric current measured the scattered signal, and a circular scale supplied angular readings. They first scanned the chamber at fixed crystal orientation, then swept crystal and chamber together to follow the reflection. [ref]
The Reflection of X-rays by Crystals by William Henry Bragg and William Lawrence Bragg. Bragg and Bragg (1913), pp. 428–430: preparation, source, slits, chamber, angular scale and scanning
Changing chamber gas checked detector dependence; readings on opposite sides checked face-setting errors. Repeated peaks with sines of half-deflections in integer ratios, together with matching absorption coefficients, distinguished repeated diffraction orders of the same wavelength from different radiation components. Comparing crystal faces constrained interplanar spacings. Their limits included slit broadening, face alignment and incomplete interception at glancing incidence; assigning absolute wavelengths still required a structural choice for . [ref]
The Reflection of X-rays by Crystals by William Henry Bragg and William Lawrence Bragg. pp. 428–430: gas and alignment controls; pp. 435–437 and Fig. 3: order comparison, absorption test, finite-face limitation and spacing ambiguity
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