Optical properties of liquid metals at high temperatures

Abstract

Measurements have been made, by a polarimetric method, of the optical properties of seven liquid metals, in the frequency range between 0·77 and 5·0 ev and at temperatures up to 1600°c. For Al the results show no sign of the absorption peak at about 1·5 ev which is observed for the solid and are in rough agreement with the Drude free-electron curves; deviations from these curves may be due to surface contamination, though an attempt to explain them quantitatively in this way is not successful. For Cu, Ag and Au the results at low frequencies suggest that the effective density of conduction electrons, n∗, rises slightly on melting, as is to be expected if the structure of the conduction band is smoothed out; the absorption edges due to excitation of electrons from the d band, however, are scarcely changed at all. For the transition metals Fe, Co and Ni, which lie next to one another in the Periodic Table, the absorption spectra show little in the way of structure; the most notable feature of the results is that the magnitude of the absorption is much the same for all three.