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Spin resolved (e,2e) experiments provide an extremely sensitive test of theories of electron impact ionization and many-body Coulomb effects. We present here results for (e,2e) collisions with xenon which show the first experimental evidence of the fine structure effect in electron impact ionization, analogous to the well known effect in electron impact excitation of atoms by polarized electrons. Comparison with distorted-wave Born-approximation calculations shows the sensitivity of the results to details of the target atom wave functions as well as the treatment of relativistic effects. PACS numbers: 34.80.Dp, 34.80.Nzwhere s " J and s # J are, respectively, the ͑e, 2e͒ differential cross sections to the final ion state of angular momentum J for incident electrons with spin up and spin down perpendicular to the scattering plane. Experimentally, A J is determined from the relation

In a series of experiments investigating the spin-dependent aspects of electron impact induced ionisation of atoms with a spin-resolved incident electron beam we have measured spin-resolved (e,2e) cross sections for xenon. By experimentally resolving the fine structure levels of the ground state residual ion the existence of an effect analogous to the fine structure effect in excitation has been established, whereby strong and opposite polarisation effects are observed in the ionisation of a spinless closed shell target leading to a fine structure doublet.

We have developed fluoride antireflection (AR) coatings on MgF(2) substrates for a wavelength of 248 nm by molecular-beam deposition. Transmission and laser-induced damage threshold of the samples were measured and atomic force microscope (AFM) investigations were carried out. We compare a 14-layer design for AR coatings with sublayer thicknesses of 12 nm with a conventional two-layer design with quarter-wavelength thicknesses. The laser-induced damage threshold of the 14-layer coating is slightly higher than that of the two-layer coating. The AFM surface images show that the 14-layer coating has a smoother surface than the two-layer coating.