Abstract
A study of the excitation spectrum of singly ionized zinc in germanium under very high signal-to-noise ratios has revealed the A, A, and G lines of this acceptor; the latter line is extremely weak. A number of further features have been observed at stresses higher than those previously used. The most striking effect is the dramatic growth of the G components under stress due to very strong interaction between the substates of the excited state of the G line and those of the excited state of the D line. This interaction also causes strong nonlinear effects in the stress dependence of the energies of the stress-induced components of the excitation lines. More reliable deformation-potential constants are obtained than those previously given.