In addition, the X-ray's wavelength should be close to the heavy atom's absorption edge.
Henry further realized that these discrete electron states would greatly alter the optical absorption edge of the semiconductor.
Under high resolution spectroscopy, the absorption edge has structure.
This results in an absorption edge.
Each element on the periodic table has a set of unique absorption edges corresponding to different binding energies of its electrons.
In general the X-ray form factor is complex but the imaginary components only become large near an absorption edge.
Particular elemental constituents can be located using measurements on each side of an absorption edge to give an element-specific difference image with moderate sensitivity.
In this compound, rubidium atoms were the ones close to the absorption edge.
Henry then calculated how this quantization would alter the optical absorption edge of the semiconductor.
The difference in usage is the energy range above the absorption edge.