Experimental and Theoretical Investigations on the Picosecond Deactivation Process of Excited F‐Centres in KCl

Abstract

The deactivation behaviour of optically excited F‐centres in KCl is investigated for the first time by picosecond laser spectroscopy. It is found, that a certain portion of them returns to the ground state during 20 to 150 ps. This fast deactivation process, which depends on the F‐center concentration and the coloration method, can be explained by a model based on energy transfer between excited F‐centres, whereby an inhomogeneous spatial distribution can be taken into account. The critical transfer distance is observed to be R0 = (106 ± 15) Å. Quantitative characteristic results about the inhomogeneous spatial distribution of the F‐centres are presented.

Ionic and electronic processes during frenkel defect annealing in KBr crystals above LHeT

“…I n addition to the above mentioned, it is important to stress the results of the picosecond laser spectroscopy recently obtained by Schubert and Vogler [26]. They found that the laser excitation in the F band of the KCl crystal containing above lo1' F centres resulted in a decreasing lifetime of the excited state for a fraction of the F centres by about five orders, down to 20 ps.…”

Two‐photon absorption of F‐centres in KCl

“…Within this concentration range mutual F-centre interactions causing distortions of the spontaneous emission decay can be excluded [5].…”