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Understanding Luminescence Spectra and Efficiency Using Wp and Related Functions: 13 (Inorganic Chemistry Concepts) - Tapa blanda

Struck, Charles W. W.; Fonger, William H.

 
9783642486319: Understanding Luminescence Spectra and Efficiency Using Wp and Related Functions: 13 (Inorganic Chemistry Concepts)

Sinopsis

This book gives a semiquantitative understanding of the properties observed in luminescence, i.e., where energy absorption and emission occur, and with what efficiency these conversion processes take place. The authors give a correct treatment of the offset dependence and the temperature dependence of nonradiative rates. The Wp function is defined as the sum of thermally weighted Franck-Condon factors. It is obtained in one dimension in several forms, and a useful recursion relation is derived between Wp's with nearby p indices.

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Reseña del editor

There are both a remote and a proximate history in the development of this book. We would like to acknowledge first the perceptiveness of the technical administrators at RCA Laboratories, Inc. during the 1970s, and in particular Dr. P. N. Yocom. Buoyed up by the financial importance of yttrium oxysulfide: europium as the red phosphor of color television tubes, they allowed us almost a decade of close cooperation aimed at understanding the performance of this phosphor. It is significant that we shared an approach to research in an industrial laboratory which allowed us to avoid the lure of "first-principles" approaches (which would have been severely premature) and freed us to formulate and to study the important issues directly. We searched for a semiquantitative understanding of the properties observed in luminescence, i. e. , where energy absorption occurs, where emission occurs, and with what efficiency this conversion process takes place. We were aware that the nonradi­ ative transition rates found in practice vary enormously with temperature and, for a given activator, with small changes in its environment. We traced the source of this enormous variation to the magnitude of the vibrational overlap integrals, which have strong dependences on the rearrangements occurring during optical transitions and on the vibrational number of the initial electronic state. We were willing to excise from the problem the electronic aspects - the electronic wavefunctions' and their transition integrals -by treating them as parameters to be obtained from the experimental data.

Reseña del editor

This book gives a semiquantitative understanding of the properties observed in luminescence, i.e., where energy absorption and emission occur, and with what efficiency these conversion processes take place. The authors give a correct treatment of the offset dependence and the temperature dependence of nonradiative rates. The Wp function is defined as the sum of thermally weighted Franck-Condon factors. It is obtained in one dimension in several forms, and a useful recursion relation is derived between Wp's with nearby p indices. Two classes of applications are considered. First, an exposition of the broad classes of luminescence behavior is given and the Wp function and related functions are applied to each. Then the detailed application of these functions to specific experimental data, namely, to Eu3+, Tm3+, and Yb3+ in oxysulfides and oxychlorides and to Cr3+ in ruby is extensively discussed. The authors give a thorough review of the related literature. The many exact and approximate forms, some with certain errors, for Wp and related functions are listed and their relationship to Wp are given.

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