Photoluminescence from excitons in ZrS3

The photoluminescence spectrum of the layered ZrS₃ crystal shows several narrow emission lines under the excitation by an Ar⁺ laser in the wavelength range from 605–630 nm at 4.2 K. The excitation spectra for these emission lines and their temperature dependences suggest that the observed narrow emission lines originate from the radiative annihilation of indirect excitons bound to impurities. Some of these emission lines seem to be associated with the radiative annihilation of the indirect bound exciton with emission of phonons.