ON CONTOUR OF ABSORPTION LINES IN CU2O

The contour of the absorption spectrum in Cu2O has been measured at various temperatures between 4.2°K and 298°K. The broadenings and the asymmetries of the absorption lines have been analyzed on the basis of Toyozawa's theory on the general problem of the exciton-phonon interaction: Half-value widths of the yellow- and green-series absorption lines are proportional to temperature above about 80°K. The asymmetries of the yellow-series absorption lines increase as temperature rises, while those of the green-series lines are nearly constant. The observed contours of the yellow-series absorption lines agree with the asymmetric Lorentzian fairly well. On the contrary, the green-series n=2 line observed at various temperatures deviates slightly from the asymmetric Lorentzian on the high energy side of the peak position. The origin of the line broadening with asymmetry is discussed in terms of the interband exciton scattering by phonons. © 1969, THE PHYSICAL SOCIETY OF JAPAN. All rights reserved.