Reflectance and optical constants of evaporated ruthenium in the vacuum ultraviolet from 300 to 2000 Angstroms

The reflectance and optical constants of evaporated ruthenium films were measured in the wavelength region from 300 to 2000 A. The films were evaporated by electron bombardment in an ion-titanium-pumped vacuum system and were typically deposited at a rate of about 40 A/s onto glass and super-polished fused-quartz substrates which were at 40 and 300 °C. Variation of deposition rate from 1 to 80 A/s had very little effect on their reflectance. The optical constants were determined from reflectance measurements made at several angles of incidence. Reflectance losses during extended exposure to air were rather small, indicating that, if oxide films form at room temperature, they are very thin. Films made on substrates at 300°C had slightly higher reflectances than those made at 40°C. Owing to interference effects, semitransparent films 150 to 200 A thick showed higher reflectances than opaque films at wavelengths in the region of 584 A. At wavelengths near 2000 A, films 300 A thick had highest reflectances. Ruthenium films prepared under optimum conditions had reflectances of 26% at 584 A.