The optical properties of lead in the energy range 0·6-6 ev

An ellipsometer used with the sample enclosed in an ultra-high vacuum chamber is described. It permits the determination of optical constants of evaporated films in vacua ∼5 × 10−10 torr. Lead films have been studied in the energy range 0·6 to 6 ev. The absolute values of optical absorption are considerably higher than previous published values. Since it is shown that exposure to air causes a large decrease in size it is considered that the high values are characteristic of clean lead. The absorption spectrum is discussed in terms of Loucks’ band structure calculation. Assignments of interband transitions are made and reasonable agreement between experiment and band calculation found.