Energy transfer processes in polymers

Number of molecules of low molecular weight gaseous product 

Quantum yields are defined only for specific wavelengths. They are not applicable to polychromatic light sources, especially in combination with broad absorption of the irradiated systems, and must be substituted by empirically determined irradiation times. Studies of the variation in the quantum efficiencies of various primary photochemical processes in polymers show very little dependence on molecular weight [858, 871]. 

An electronic energy transfer process is the one-step transfer of electronic excitation energy from an excited donor molecule (D ) to an acceptor molecule (A) in separate molecules (intermolecular energy transfer) or in a different part of the same molecule (intramolecular energy transfer) [863,867, 1766, 1804, 2161, 2162, 2220]. 

Electronic energy transfer process may occur by the following mechanisms  

Electron exchange energy transfer, which occurs when an excited donor molecule (D ) and an acceptor molecule A) are close enough (10-15 A) that they may be considered to be in molecular contact, i.e. their centres are separated by the sum of their molecular radii. Their electron clouds may overlap each other and an electron on D may also appear on A. 

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Investigations into singlet—singlet energy transfer processes in polymers have been mainly concerned with polymers containing aromatic chromo-phores such as polystyrene, polyvinylnaphthalene, polyacenaphthalene and polyvinylcarbazole. With these, excimer formation is possible as a consequence of the interaction of an excited and a ground state chromo-phore. In the presence of a suitable acceptor, energy transfer in the polymer can occur either from an isolated excited state or from an excimer... 

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