On the oscillator strength of F centers in alkali halides

Abstract

A radiochemical method, previously applied t o NaCI, KCI, and KBr crystals has been used to determine the oscillator strength f of F-centers in RbCI. By extending theoretical calculations carried out by Smith and Spinolo, and by Iadonisi and Preziosi, estimates of f for several alkali halides, including those previously mentioned, have been computed.

Determination of the oscillator strength of F centres in KBr-In by photostimulated luminescence

“…Now, when the uM-and H-values have been obtained from the PSL stimulation experiments, we may calculate fby means of equation (4). Substituting uM = 2.0 x 10l6 cm', H = 0.32 eV and n = 1.559 [3,4] into equation (4) we g e t f = 0.66. This result is shown in table 2 together with all previous published data onffor KBr-In crystals.…”

“…Now let us remember that xlrl and N , are related by the equation where U, is the effective absorption cross section in the absorption band peak. Then from equations ( 2) and (3) we easily obtain…”

An experiment with manifold purposes: the chemical reactivity of crystal defects upon crystal dissolution

“…At the same time, it was implicitly proven that the ejq are generated in amounts suitable for investigating their chemical reactivity (2). In addition, the method devised for counting e7q, and therefore the F centers, has been applied to determination of the oscillator strength of the F centers in several alkali halides (3,4).Since the techniques used in these experiments are not too complicated and the instrumentation required is available in all radiochemical laboratories, we have tried to adapt these measurements for use as a classroom experiment in either a radiochemistry course or a solid state physical chemistry course. This experiment will introduce:1) crystal defects and their reactivity upon crystal dissolution; 2) the hydrated electron and its reactivity; 3) an application of the radiochemical method of analysis; 4) the technique of competitive kinetics (even though it is applied to a rather particular case).…”

“…At the same time, it was implicitly proven that the ejq are generated in amounts suitable for investigating their chemical reactivity (2). In addition, the method devised for counting e7q, and therefore the F centers, has been applied to determination of the oscillator strength of the F centers in several alkali halides (3,4).…”