Computer simulation of collision-induced absorption in a two-dimensional Lorentz gas

We report computer simulations of collision-induced light absorption in a two-dimensional Lorentz gas over a range of densities, which we compare with theories of the intracollisional spectrum, intercollisional interference, and pressure narrowing. The theory of Lewis and Van Kranendonk successfully fits the simulation spectra at low densities, but attempts to extend it require unrealistic distributions of collision times. Instead of pressure narrowing we observe pressure broadening with formation of a spike probably due to a cage effect.