ON SHOULDER BANDS OF U BAND

Two shoulder bands of the U band are theoretically investigated by computing absorption energies for optical transitions from the ground state of the U center to its high excited singlet states. The calculation is done by using the polaron model developed in a recent paper. The comparison of theoretical results with experimental results of the two shoulder bands shows that (a) one of the two shoulder bands (the Ua band) arises from the optical transition to the 1s3p-like singlet excited state and (b) the other (the Ub band) arises from the optical transitions to the 1snp-like singlet excited states with n ≥ 4 modified by the crystal field. © 1969.