Temperature phosphorescence semiconductor

A wide variety of different mechanisms may participate in the PT process and influence the interpretadon of a spectrum. At room temperature, PL emission is thermally broadened. As the temperature is lowered, features tend to become sharper, and PL is often stronger due to fewer nonradiadve channels. Low temperatures are typically used to study phosphorescence in organic materials or to identify particular impurides in semiconductors. 

Many materials benefit from analysis at cryogenic temperatures. At 77 K, enhanced fluorescence and phosphorescence are seen, and low-temperature studies are used for elucidation of the mechanisms of photochemical reactions, characterizing bandgap changes in semiconductors and other applications. 

Table 6.2 Chemical structures and phase transition temperatures of some liquid crystaUine semiconductors 7-9 and 12 and phosphorescent emitters 10 and 11 ...

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