On the transport of activated particles by flow and diffusion

It will be shown, how the spatial decay of active molecules — excited electronically or activated otherwise (e.g., chemical processes) is determined by diffusion and flow as well as by the intrinsic molecular constant. The exact analysis in cylindric geometry leads to a set of unique solutions, which in lowest order are characterized by a weak gradient of the particle concentration at the wall and a pronounced kernel in the center of the tube. In special cases there exists a simple but powerfull expansion of any distribution in the source, which are very similar to Fourier-Bessel series. The solutions in lowest order will be used to analyze the measured decay of activated oxygen in a steady stream of molecular oxygen. Since the decay constant is determined by volume deactivation and by the removal of particles at the wall, evaluation of experimental data, however, remains necessarily ambiguous.