Optical examination of the electronic structure of single-crystal hcp scandium

The optical absorptivity of a single oriented crystal of high-purity hcp scandium metal has been measured between 0.2 and 5 eV. The optical-conductivity spectra have been determined through Kramers-Kronig analysis. The results for scandium are compared with earlier results for single-crystal yttrium and the heavy lanthanide metals, particularly lutetium. Very strong similarities are shown to exist with nearly a one-to-one correspondence of structures for the various metals. The data are interpreted in terms of recent Sc band calculations by Das, and extensions of the calculations to other hcp metals, including considerations of dipole matrix elements, are urged.