To what extent are the observed lifetimes of F‐centers intrinsic?

New measurements, performed at near 65 K, of the F-center radiative lifetime τR in KBr samples containing α- and F'-centers show a τR-increase which is related to low and, in some cases, scarcely detectable, critical α-center concentrations. Analysis of experiments known in literature reveals that a far from negligible quantity of α-centers is always present in real crystals. These facts lead us to the stimulating hypothesis that the τR-values might be incorrect because of the perturbation due to the interaction between F- and α-centers. Neue Messungen bei ungefahr 65 K zeigen eine Zunahme der Strahlungslebensdauer τR des F-Zentrums in KBr-Kristallen, die α- und F'-Zentren enthalten. Diese Zunahme ist mit einer kritischen Konzentration von α-Zentren verbunden, die meistens sehr klein und in manchen Fallen schwerlich mesbar ist. Aus einer Analyse der verschiedenen experimentellen Ergebnisse, die in der Literatur beschrieben sind, geht deutlich hervor, das in Realkristallen immer eine nicht unbedeutende Menge von α-Zentren vorhanden ist. Diese Tatsachen fuhren zu der provozierenden Annahme, das die bekannten τR-Werte, infolge der Wechselwirkung zwischen F- und α-Zentren nicht genau sind.

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