Fluorescence, delayed, £-type intensity measurements

The photophysical investigation of the exciplex formed between 4,4, 4"-tris[3-methylphenyl(phenyl)amino] triphenylamine (m-MTDATA) and 2-(biphenyl-4-yl)-5-(4-tert-butylphenyl)-l,3,4-oxadiazole (PBD) in a 50 50 blended film showed that the mechanism behind extra singlet production was consistent with the photoluminescence being enhanced via thermally activated delayed fluorescence (E-type nature). Measurements of the emission intensity change with temperature were used to estimate the exciplex singlet-triplet energy splitting to be around 5 meV. 

Phosphorescence can be observed without interference from fluorescence by a process called time resolution. Instruments for measuring phosphorescence are very similar to those used for fluorescence but a mechanism that allows the sample to be irradiated and then, after a time delay, allows measurement of phosphorescent intensity (phosphoroscope) is required as an extra component. The instrument should also have the capability of keeping samples at very low temperatures. Another type of long-lived photoluminescence is time-delayed fluorescence, where the electrons in the molecule obtain enough energy to be excited from a special excited state to the normal excited state and then fluoresce. 

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