Analysis of Wavelength Derivative Spectra of Exciton in Cu₂O

Abstract

The line shapes of the exciton absorption spectra of Cu₂O at various temperatures obtained by the wavelength modulation technique have been analysed on the basis of Toyozawa’s theory. The n-th exciton lines for the yellow (n≥2) and the green exciton series have asymmetric Lorentzian line shape and their half value widths are proportional to T (the absolute temperature) in a high temperature region. While the yellow 1s line has a characteristic line shape with the half value width proportional to T². The temperature change of the spectrum indicates that the Γ₁₂⁻ optical phonon in Cu₂O plays a predominant role in the exciton-phonon interaction.