TOF distributions of Ar atoms that scattered from FiberForm allowed us to analyze geometrical effects of the carbon fiber network on the scattering dynamics of particles that have no reactive interactions with the fibers. TOF distributions of scattered Ar corresponding to different sample temperatures and θi = θf = 45° are shown in Figure . Bimodal TOF distributions such as these are commonly described in terms of two limiting cases : (1) non-thermal, impulsive scattering (IS), and (2) thermal desorption (TD). The IS component originates from atoms or molecules that undergo one or a few collisions on a surface before exiting to the gas phase with super-thermal velocities. Thus, IS products are characterized by early arrival times in a TOF distribution. In most cases, IS atoms or molecules retain some memory of the impinging collisions, and the dynamical behavior of the IS component typically depends on the incidence energy and angle . The TD component originates from atoms or molecules that have a strong enough interaction with the surface to come into thermal equilibrium before desorbing, often with a Maxwell-Boltzmann (MB) velocity distribution at the relevant surface temperature.