Defects in Salt Crystals

The colors of halide salts containing F-center defects correlate with the size of the halide vacancy, as expected for a particle in a box.

Clicking a thumbnail on this web page (http://chemistry.beloit.edu/edetc/cineplex/Fcenter/index.html) shows a movie of that demonstration.

NaCl in an evacuated flask is excited with a Tesla coil.

KCl in an evacuated flask is excited with a Tesla coil.

KBr in an evacuated flask is excited with a Tesla coil.

Excitation of NaCl, KCl, and KBr with a Tesla coil.

Pouring irradiated NaCl onto a hotplate releases the defect.

Absorption spectra obtained from color centers in halide salts exhibit a clear trend in the variation of the wavelength with the size of the halide vacancy (as estimated by the lattice parameter, the length of an edge of the cubic unit cell).

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