Linear and nonlinear FEL-SEW spectroscopic characterization of nanometer-thick films

The conditions of the existence and transformations of surface electromagnetic waves (SEWs) on metals (surface plasmons) and dielectrics (phonon-polaritons) are discussed, Interferometric SEW experiments provide the possibility for the direct determination of the real and imaginary parts of the dielectric constants E at the frequencies in the tuning range of a free electron laser (FEL) without and preliminary epsilon models, The important role of the outstanding facilities of FEL-namely, the broad tuning range, high power, narrow bandwidth of emission, and well-collimated beam-in SEW experiments is outlined, it is demonstrated 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 CaF2 and the thin polymeric him were studied by an interferometric experiment 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 dependence of SHG, and the influence of a thin-film deposition on a quartz surface-are described.