Transmittance and optical constants of Pr films in the 4-1600 eV spectral range

The optical constants of Pr films were obtained in the 4-1600 eV range from transmittance measurements performed at room temperature. Thin films of polycrystalline Pr were deposited by evaporation in ultrahigh vacuum conditions and their transmittance was measured in situ. Pr films were deposited onto grids coated with a thin, C support film. Transmittance measurements were used to obtain the optical extinction coefficient k of Pr films in the 4-1600 investigated photon energy range. The refractive index n of Pr was calculated using the Kramers-Kronig analysis. Data were extrapolated both on the high and low-energy sides by using experimental and calculated extinction coefficient data available from the literature. Pr, similar to other lanthanides, has a low-absorption band right below the O-2,O-3 edge onset; the lowest absorption was measured at about 17 eV. Therefore, Pr is a promising material for filters and multilayer coatings in the energy range below O-2,O-3 edge in which most materials have a strong absorption. A good consistency of the data were obtained through f and inertial sum rules. (C) 2008 American Institute of Physics.