Poly , triplet absorbance

Studies of the triplet-triplet absorption spectrum of P1VN 59) and P2VN 60-61> in degassed fluid solution have shown that triplet annihilation is still important at room temperature. The triplet absorbance of dilute poly(vinylnaphthalene) solutions is only 0.05-0.2 times as large as that of the corresponding ethylnaphthalene solution having the same concentration of naphthyl groups. While quantitative data on kMXX at room temperature are unavailable, the ordinary triplet decay rate kx has been extensively studied for monochromophoric compounds. 

The existence of differential reactivity for various sites suggests the possibility that energy absorbed at one site on the chain may be transferred down the chain until it localizes in a site with an unusually high cross section for reaction. Shulman, Gueron, and Eisinger154 claim that energy absorbed in poly dAT at the excited singlet level is transferred to a common excimer between A and T, whence it crosses to a triplet triplet excitons have been observed in poly A with a jump time of 10"8 to 10 10 sec. 

Energy migration in polymer films via triplet or singlet excitons is potentially applicable to "photon harvesting". Unfortunately many polymers possess pendent chromophores that absorb only in the UV. Experiments at 77K on poly(2-vinylnaphthalene)... 

The present paper is an example of the latter approach, applied to poly(2-vinylnaphthalene) (P2VN). However, rather than add a sensitizer molecule that absorbs in the visible but with a triplet state of higher energy than of P2VN, we have used 1,2,-... 

Fig. 2. Schematic model of extended poly(l-vinylnaphthalene) with triplet donor molecules M (O ). 2 denotes a naphthalene moiety and hiT the incident photon absorbed by M. M inter system crosses before transferring its excitation energy to pendent groups.

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