Two-photon evanescent wave spectroscopy: a novel technique for exploiting gas-surface dynamics in the boundary layer

Summary form only given. Resonant optics at a gas-solid interface can exhibit unprecedented sensitivity to gas-surface interactions if one restricts the gas volume that determines the optical response to very small distances to the surface. In the case of evanescent wave or surface plasmon spectroscopy the excited gas volume is limited by the depth of the wave penetration into the gas. Due to this fact the corresponding optical spectra are very sensitive to the polarization behavior of the gas near the surface. Because this behavior is different for atoms or molecules moving to the surface compared to those that depart from it, one can distinguish in a spectroscopic manner between the contributions. Of course, this is only possible if a quantitative theoretical description of the experimentally observed line shapes is available. We have developed the corresponding theory previously and have it modified to match the present experimental conditions.