Optical properties of liquid Pb and Bi between 0.6 and 3.7 eV

Optical properties of liquid Pb and Bi were determined at 341 and 2850C, respectively, for photon energies between 0.6 and 3.7 eV, with the use of an ultra-high-vacuum ellipsometer. It was found that liquid Pb exhibits absorption in excess of Drude absorption, with a structure strikingly similar to the interband absorption in solid Pb. The liquid-to-solid ratio of the interband intensity was found to be 0.22, and 11% of the total valence oscillator strength in the liquid was attributable to the interband transitions. Liquid Bi was also found to exhibit excess absorption at energies above 2.5 eV. These non-Drude behaviors of both liquids were found to be explained as a density-of-states effect by assuming the nondirect model for optical transitions in liquid metals