Optical properties of thin lead films in the energy range 3-15.5 eV evaporated and studied in ultrahigh vacuum

Reflectance measurements, in situ, on freshly deposited thin lead films are carried out in the far uv. Optical constants and other useful functions such as ${\epsilon }_1$, ${\epsilon }_2$, $-\mathrm{Im}\left({\epsilon }^{-1\mathrm{}}\right)$, $-\mathrm{Im}{(\epsilon +1)}^{-1\mathrm{}}$ are deduced. The existence of volume and surface plasmons is demonstrated. The structure of ${\epsilon }_2$ is attributed to interband transitions both at critical points and between parallel bands; for the latter there is reasonable agreement between the experimental data and Ashcroft's calculation.