Probing the dynamics of a polymer with paramagnetic end groups by magnetic fields

We show that magnetic field effects observed on reactions between two paramagnetic end groups of a polymer can be explained through the folding motion of the polymer. This folding stochastically alters the exchange interaction between the paramagnetic end groups and, thereby, affects their spin dynamics. We describe the resulting stochastic quantum system by a (Monte Carlo) computer simulation as well as by a new approximation which involves the spectrum of the stochastic interaction. This approximation can be of general use for the description of stochastic quantum systems when a diagonal stochastic interaction originates from an arbitrary, i.e., nonlinear and non-Gaussian, stochastic process.