LAUSR

Abstract Optical properties of indium-exchanged mordenite (MOR) zeolite have been studied using diffuse reflectance UV-Vis and photoluminescence (PL) spectroscopy. It has been found that reduced In-MOR zeolites, containing low-valence In+ exchange cations, can exhibit efficient ultraviolet and visible-light photoluminescence emissions of similar intensities. The results of the current study along with previous results on indium-exchanged ZSM-5 zeolite confirm previously made suggestion that the ultraviolet emission is associated with isolated In+ cations, while the visible-light photoluminescence is due to radiative relaxation of In+ excited-state oligomers/clusters. The PL properties of indium-exchanged zeolites thus can be tuned by changing the distance between In+ cations which in its turn can be controlled by indium loading and Si/Al ration in a zeolite framework.