Calculating X-ray absorption near-edge structure at very low energy.

The measurement and calculation of X-ray absorption near-edge structure at very low energy can provide important information about a metallic center in biological compounds. A rapid overview of the biological applications of this technique is given, then a new method of calculating the spectra is presented. This technique, based on the use of the finite-difference method to solve the Schrödinger equation, is especially precise and potentially applicable to metalloproteins. Examples of its use on an oxide and an organic compound illustrate the kind of spectroscopic information that can be obtained.