# Difference between revisions of "Absorption edge"

### From Online Dictionary of Crystallography

Arête d'absorption (Fr). Absorptionskante (Ge). Spigolo di assorbimento (It). 吸収端 (Ja). край поглощения (Ru). Canto de absorción (Sp).

## Definition

An absorption edge is the energy at which there is a sharp rise (discontinuity) in the (linear) absorption coefficient of X-rays by an element, which occurs when the energy of the photon corresponds to the energy of a shell of the atom (K, LI, LII, LIII, etc. corresponding to the creation of electron holes in the 122s22, 2s, 2p1/2, 2p3/2 etc. atomic subshells).

Associated with this transition is the absorption threshold (q.v.) characterized by the corresponding energy E0.

## Examples

For gallium: $\lambda_{K}$ = 1.1958 Ǻ; $\lambda_{L_{I}}$ = 9.5446 Ǻ; $\lambda_{L_{II}}$ = 10.8414 Ǻ; $\lambda_{L_{III}}$= 11.1038 Ǻ.

For arsenic: $\lambda_{K}$ = 1.0448 Ǻ; $\lambda_{L_{I}}$ = 8.1195 Ǻ; $\lambda_{L_{II}}$ = 9.1187 Ǻ; $\lambda_{L_{III}}$= 9.3617 Ǻ.