FINE-STRUCTURE OF P-EXCITONS IN CUBR

A multiplet structure of the 2P, 3P, and 4P exciton of the Z1,2‐series is observed in the two‐photon absorption spectrum of CuBr. It is shown that the P‐exciton fine structure results from a coupling between the angular momentum of the P exciton and the hole quasi‐spin associated with the Γ8 valence band. For the first time the energies of higher excited P excitons (3P) are compared with the theory of Baldereschi and Lipari. Therefore, the binding energies of the 3P excitons for a representative set of parameters μ and δ is calculated. Numerical calculations are performed using the “finite‐element method” (FEM). From the energy positions of nine excitons the effective Rydberg, the gap, and the parameters μ and δ of CuBr are determined with high accuracy. These data and the static dielectric constant are used to evaluate the reduced mass parameter γ1 and the Γ8 valence band parameters γ2 and γ3. The 3P exciton wave functions, calculated also with the FEM, are shown in addition. Copyright © 1979 WILEY‐VCH Verlag GmbH & Co. KGaA