LINEAR AND NONLINEAR FEL-SEW SPECTROSCOPIC CHARACTERIZATION OF NANOMETER-THICK FILMS

The conditions of the existence and transformations of surface electro magnetic waves (SEWs) on metals (surface plasmons) and dielectrics (ph onon-polaritons) are discussed, Interferometric SEW experiments provid e the possibility for the direct determination of the real and imagina ry parts of the dielectric constants E at the frequencies in the tunin g range of a free electron laser (FEL) without and preliminary epsilon models, The important role of the outstanding facilities of FEL-namel y, the broad tuning range, high power, narrow bandwidth of emission, a nd well-collimated beam-in SEW experiments is outlined, it is demonstr ated by the examples of the infrared absorption spectra of a Langmuir- Blodgett film on metal, of a metal oxide film, and of polymeric films of nanometer thicknesses on metals, Free surfaces of single-crystal Ca F2 and the thin polymeric him were studied by an interferometric exper iment for the optical constant determination, Nonlinear spectroscopic applications of the SEW-FEL technique to studies of a second harmonic generation (SHG)-the frequency dependence of efficiency, the angle dep endence of SHG, and the influence of a thin-film deposition on a quart z surface-are described.