The effect of polymer film elongation leading to the thinning of the film up to three times on the decay of transients was studied. Kinetics of benzophenone (B) triplet state B-3* and ketyl free radical BH center dot in soft rubber poly(ethylene-co-butylene) (abbreviated as E) was investigated by nanosecond laser flash photolysis. We monitored decay kinetics of the triplet state of B-3* and of BH center dot decay in the polymer cage and decay of BIT center dot in the polymer bulk. The fast exponential decay of B-3*(lifetime tau(T) approximate to 200 ns) is accompanied by hydrogen atom abstraction from E with the formation of BH center dot and a polymer free radical R center dot. The decay of BH center dot in the polymer cage occurs during tau(c) approximate to 1 us. Cage recombination, in turn, was followed by a cross-termination of BH center dot in the polymer bulk (tau(b) approximate to 100 mu s under our conditions) and is characterized by a rate constant k(b) approximate to 10(8) M-1 s(-1). We studied changes of rates of transients decay upon elongation (thinning) of E. Decay of B-3* is practically independent of elongation of the film. Recombination of BH center dot in the solvent bulk occurs with a two times lower k(b) than in a nonelongated E. The decrease in k(b) is ascribed mainly to a lower fractional polymer free volume V-f in elongated E compared with that in nonelongated E. Dependencies of log(10) k(b) versus l(-1), where l is the thickness of the film, turned out to be linear with a negative slope. At the same l recombination proceeds slower in the elongated elastomer compared with the nonelongated elastomer. Cage effect increases twice as well due to a lower rate of radicals escape from the polymer cage in the elongated film. We observed relatively large effects of external magnetic field (B = 0.2T) on the kinetics of cage recombination and recombination in the polymer bulk. Magnetic field effect on recombination rates in the cage and in the solvent bulk does not depend on elongation.