An x-ray beam, containing radiation of two distinct wavelengths, is scattered from a crystal, yielding the intensity spectrum, as shown in the figure. The interplanar spacing of the scattering planes is 0.94 nm. We have to determine the wavelength of the x rays present in the beam.
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Solution: Click For PDF Version The Bragg’ law for crystal diffraction is
where d is the lattice spacing.
From the
figure we note that the scattering angles are small and
From the
intensity pattern shown in the figure, we note that diffraction
intensity peaks at
We thus have
The lattice spacing
Using the Bragg’s law we find that the radiation contains the following two wavelengths;
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correspond to first and second diffraction orders for one
wavelength, and those at
correspond
to the first and second diffraction orders for the second
wavelength.
