Phosphorescence advantages relative

In order to demonstrate this effect to best advantage it was necessary to choose a PVCA sample having a relatively low molecular weight. In this way Interference of the phosphorescence emission by delayed fluorescence is minimized. These are provacative results because they indicate that there may be no well defined lowest triplet state in vinyl aromatic polymers unless special steric or electronic effects are present which nullify inter-chromophore interactions. On the other hand, they may provide an additional tool with which to investigate rates of energy migration in polymers and in some polymer/dopant systems as well. 

Elsewhere in this volume Millhauser et al. have discussed the application of nitroxide electron paramagnetic resonance (EPR) spin labels to the study of the structure and dynamics of biopolymers. Another type of EPR spin label that also is useful for investigating biopolymer systems is provided by the photoexcited triplet state of an intrinsic chromophore, because a triplet state carries electronic paramagnetism. A major advantage of the photoexcited triplet state of an intrinsic chromophore over an extrinsic spin label such as a nitroxide adduct is the relatively small structural perturbation caused by the former, which consists only of a localized electronic excitation. Although not as widely exploited as fluorescence, the phosphorescence of proteins, originating from the photoexcited triplet state, has received a great deal of attention. EPR afficionados have a natural attraction to photoexcited triplet states that dates back to the... 

The MLCs have several advantages over the phosphorescent probes. In contrast to phosphorescence, the luminescence from MLCs can be measured in the presence of dissolved oxygen. The MLCs are only partially quenched by ambient oxygen, whereas phosphorescence is usually completely quenched. Additionally, there are relatively few phosphorescent probes, but there are numerous MLCs (Chapter 20). 

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