Long-time behavior of photon diffusion in an absorbing medium: application to time-resolved spectroscopy.

We have investigated the motion of photons after the injection of a light pulse into a highly scattering, inhomogeneous absorbing medium. We show that the terminal slope of the logarithm of the transmittance curve does not depend on the positions of the source or of the detector. We use numerical calculations to follow the motion of photons in a model system to further understand the physical process that gives rise to this result.