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The reflectance of freshly deposited SiC thin films is measured in situ for what we believe is the first time. SiC was deposited by means of ion-beam sputtering. Reflectance was measured as a function of the incidence angle in the far and extreme ultraviolet wavelengths from 58.4 to 149.2 nm. In situ measurements allowed obtaining the intrinsic reflectance of SiC films, which is somewhat larger than what had been measured for samples exposed to the atmosphere. Reflectance measurements were used to determine the optical constants of the material in the same spectral range. We compare our data to those of the literature corresponding to SiC films deposited by different techniques and exposed to the atmosphere. In situ determined optical constants will allow a more accurate design of multilayers containing ionbeam-sputtered SiC layers. OCIS codes: 260.7200, 260.7210, 230.4040, 310.6860, 230.4170.

This work discusses the experimental determination of the optical constants (refractive index) of DC-magnetron-sputtered boron carbide films in the 30-770 eV photon energy range. Transmittance measurements of three boron carbide films with thicknesses of 54.2, 79.0, and 112.5 nm were performed for this purpose. These are believed to be the first published experimental data for the refractive index of boron carbide films in the photon energy range above 160 eV and for the near-edge x-ray absorption fine structure regions around the boron K (188 eV), carbon K (284.2 eV), and oxygen K (543.1 eV) absorption edges. The density, composition, surface chemistry, and morphology of the films were also investigated using Rutherford backscattering, x-ray photoelectron spectroscopy, atomic force microscopy, scanning electron microscopy, and extreme ultraviolet reflectance measurements. OCIS codes: 340.7480, 120.4530, 310.6860, 310.6870.

Boron films deposited by evaporation with an electron-beam were found to have a relatively high reflectance in the extreme ultraviolet with values similar to those of ion-beam-sputtered (IBS) SiC and IBS [B.sub.4]C. The largest reflectance was measured for an 11 nm thick boron film. Some reflectance degradation was observed for boron films stored in a desiccator. Reflectance degradation varied from sample to sample and was found to be either similar to that of IBS SiC and IBS [B.sub.4]C or larger. OCIS codes: 260.7200, 260.7210, 230.4040, 310.6860, 230.4170.

Ion-beam sputtering (IBS) and evaporation are the two deposition techniques that have been used to deposit coatings of Al protected with Mg[F.sub.2] with high reflectance in the vacuum ultraviolet down to 115 rim. Evaporation deposited (ED) Al protected with IBS Mg[F.sub.2] resulted in a larger (smaller) reflectance below (above) 125 nm than the well-known all-evaporated coatings. A similar comparison is obtained when the Al film is deposited by IBS instead of evaporation. The lower reflectance of the coatings protected with IBS versus ED Mg[F.sub.2] above 125 nm is because of larger absorption of the former. Both nonprotected IBS Al, as well as IBS Al protected with ED Mg[F.sub.2], resulted in a band of reflectance loss that was peaked at 127 and 157 nm, respectively. This result was attributed to the excitation of surface plasmons due to the enhancement of surface roughness with large spatial wave vectors in the sputter deposition. This reflectance loss for IBS Al protected with Mg[F.sub.2] is small at the short ([lambda] ~ 120 nm) and long ([lambda] > 350 nm) wavelengths investigated. IBS Al protected with ED Mg[F.sub.2] is thus a promising coating for these two spectral regions. Coatings protected with IBS Mg[F.sub.2] resulted in a reflectance as high as coatings protected with ED Mg[F.sub.2] at wavelengths longer than 550 nm, whereas the former had a lower reflectance below this wavelength. OCIS codes: 260.7210, 260.7200, 230.4170, 120.5700, 310.6860, 350.6090.

The transmittance of silicon monoxide films prepared by thermal evaporation was measured from 7.1 to 800 eV and used to determine the optical constants of the material. The obtained values for extinction coefficient k combined with data from the literature and interpolations and extrapolations in the rest of the electromagnetic spectrum which provide a complete set of k values could be used in a Kramers-Kroning analysis to obtain the real part of the index of refraction, n.

A study was conducted to obtain the optical constants and transmittance measurements at room temperature for thulium (Tm) thin films deposited by evaporation in ultrahigh vacuum conditions. A low-absorption band below the [O.sub.2,3] edge onset observed for Tm, similar to other lanthanides, indicated the application of Tm as potential material for filters and multilayer coatings in the energy range below the [O.sub.2,3] edge.

The transmittance measurements and extinction coefficient calculations of thin films of Eu deposited by evaporation are discussed. The relatively low absorption minimum at ~16.7 eV observed for Eu has made it a promising candidate for transmittance filters and reflective multilayers.

The optical constants of Pr films are obtained in the 4-1600 eV range from transmittance measurements, where the thin films of polycrystalline Pr are deposited by evaporation in ultrahigh vacuum conditions. The studies have shown that Pr is a promising candidate for filters and multilayer coatings in the energy range below [O.sub.2,3] edge in which most materials have a strong absorption.

Transmittance measurements are used for obtaining the optical constants of Ce films in the 6-1200 eV range at room temperature. The evaluation of f and inertial sum rules has shown a good consistency of the optical constants of Ce.