absorption edge

noun Physics.
  1. a discontinuity in the graph of the absorption coefficient of a substance plotted against the wavelength of x-rays being absorbed, representing the minimum energy necessary to free electrons from particular shells of the atoms of the substance.

Origin of absorption edge

First recorded in 1925–29
Also called absorption discontinuity, absorption limit.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018