The Jahn-Teller Effect from Emission Spectra

The Jahn-Teller Effect from Emission Spectra 

During the last decade it has been observed that the excited state of optical centers is often strongly distorted due to the Jahn-Teller effect. This puts the simple configurational coordinate model with the breathing mode as a coordinate in severe doubt. Also, it now becomes clear that the Stokes shift is in many cases due to a relaxation via a Jahn-Teller active mode. Let us illustrate these statements by several examples that originate from three types of centers, viz., transition 

In connection with our treatment of the configurational coordinate diagram (see above) it should be noticed that the occurrence of two 

From intensity ratios in vibrational progression. No vibrational structure observed. 

It has long been realized that the transitions involved are of the charge-transfer t3ipe, and that the emitting state is a triplet state 96). This follows from the long decay times observed. Further characterization is hardly possible, due to the absence of any structure in the spectra. By performing EPR measurements in the excited state Van der Waals et al. were able to demonstrate directly the triplet character of this excited state. 

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VI. The Jahn-Teller Effect from Emission Spectra... 

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