Charge carrier generation thermal excitation

Finally, we would like to mention a derivative of OG spectroscopy, which is conducted not in a discharge cell but in a (hot) flame the technique is often referred to as laser-enhanced ionization (LEI). The technique is used for sensitive detection of trace atoms and molecules. The excitation of the species under investigation populates high-lying energy levels the thermal heat of the hot flame is sufficient to ionize the species out of their excited levels. Electrodes placed around the flame detect the charge carriers generated in this way. Further details on the principles and applications of OG spectroscopy and LEI can be found, for example, in Stewart et al. (1989). 

The transition to a conductive state requires the generation of charge carriers and therefore thermal excitations of the disproportionation reaction... 

In long-afterglow phosphors, optical excitation energy is stored in the lattice by trapping photoexcited charge carriers. The most prominent example is SrAl204 Eu,Dy after optical excitation of Eu, Eu is oxidized to Eu and Dy is reduced to Dy. Thermal excitation of Dy to Dy, followed by capture of the electron by Eu and subsequent Eu emission results in time-delayed Eu emission. The thermal excitation process of Dy determines the time delay. This particular material still generates visible emission after several hours in the dark. 

Fig. VC-3) [181]. Both the magnitude and the lifetime of transient PC increase by addition of a few percent C o to the pure polymer. Transient photoinduced absorption studies demonstrated rapid (sub-picosecond) photo-induced electron transfer from the polymer to C q thereby minimizing early time recombination and enhancing the quantum yield for mobile carrier generation [175,176]. If neutral excitons were the primary excitations, the observed charge transfer would be thermally activated this is not observed.

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