Dissociation of excitons in Cu2O by an electric field

The electric field-induced dissociation is studied for excited states of the yellow exciton series of ${\mathrm{Cu}}_{2}\mathrm{O}$. With increasing principal quantum number $n$, corresponding to rising exciton energy, the field strength for dissociation decreases as expected. Surprisingly, within a manifold belonging to a particular $n$ this trend is reversed as the required dissociation field increases with rising energy. In agreement with calculations we attribute this finding to the distribution of the exciton wave functions in the potential landscape. While the low energy states in the multiplet are shifted towards the side where the potential is lowered by the electric field, thereby facilitating dissociation, the high energy states are moved to the other side stabilizing them up to higher fields.