Exciton-exciton interactions in CdWO4 irradiated by intense femtosecond vacuum ultraviolet pulses

Exciton-exciton interaction is experimentally revealed and quantitatively analyzed in a wide band-gap scintillator material CdWO4. Under high-intensity femtosecond vacuum ultraviolet excitation, the CdWO4 luminescence is quenched, while its decay becomes essentially nonexponential. We propose an analytical model, which successfully reproduces the decay kinetics recorded in a wide range of excitation densities. The dipole-dipole interaction between excitons leading to their nonradiative decay is shown to be the main cause of a nonproportional response common for many scintillators.