Emission spectroscopy and electronic energy migration and transfer in polymers
Pure and Applied Chemistry
Emission spectroscopy is used to identify excited states in aromatic organic polymers and to follow the depletion processes of these states. Energy migra-(ion and transfer processes within individual polymer molecules and through bulk polymer samples can be separated and assessed through an examination of concentration effects on the emission spectra. In aromatic polymers such as polystyrene. singlet migration and excimer formation is highly efficient in properly oriented individual polymer
... cules; in the hulk polymer, excimer formation competes with other singlet trapping modes. Triplet energy migrates not only within polymer chains but also across chains in the bulk polymer. In the hulk polymer this energy can be trapped by non-polymer impurities, giving impurity phosphorescence, or by chain impurities or defects, generating delayed exciplex fluorescence as well as delayed fluorescence different from that observed in dilute solutions. From these results, it can be inferred that the photochernistry of a polymer may often reflect the photochemistry of a trap or defect.