Etude spectrophotometrique des spectres continus de Cu 2O a diverses temperatures

Abstract

The absorption of samples of different thicknesses (from 10 to 180 μ) of synthetic Cu 2O has been measured at different temperatures (293°K, 249°K, 169°K, 104°K, 77°K, 20°K, 4°K). The yellow series of Cu 2O has been studied previously.( 1) In this paper measurements in different parts of the spectrum where the absorption is continuous are reported. The red continuum is situated on the low energy side of the yellow series, the yellow continuum on the high energy side. Both are well described by Elliott's ( 2) theory of indirect and forbidden transitions. The red continuum is probably an indirect transition with phonon creation and annihilation to the first exciton state n = 1. At high temperatures, the yellow series disappears and is replaced by a continuum which is characteristic for a forbidden band to band transition. The “yellow” continuum corresponds to the continuous absorption on the high energy side of the series limit.