Effects due to variation in the alkyl chain length of photodimers of 9-alkylanthracene esters on their photodecomposition efficiencies at 12 K and, by implication, the photoproduct migration as a function of temperature within polymer hosts are investigated. It is shown that dimers with longer alkyl chains have a lower photodecomposition efficiency. The extent of photoproduct migration within the polymer following photodecomposition was also studied as a function of alkyl chain length. This migration and its modulation of the interaction between the separating monomers is shown to affect the emission spectrum. Thus, monomer migration was studied in temperature cycling experiments, It was also found, for the polymer hosts investigated-poly(methyl methacrylate), poly(vinyl chloride), and polystyrene-that these properties are host dependent. This result is probably due to the void space differences that exist among these polymers.