Optical properties of calcium in the vacuum ultraviolet

The reflectance of films of calcium has been measured at several angles of incidence in the energy range 6-30eV. The optical constants have been computed by an iterative process and the real and imaginary parts of the complex relative permittivity and the volume and surface loss functions have been calculated. The displacement of the volume plasmon energy from just below 7eV (as deduced from low energy optical measurements and as predicted by the free electron model) to over 9 eV (as found from the loss function, confirming electron energy loss measurements) is attributed to bound transitions in the regions of 5 eV.