Abstract. Time-resolved luminescence experiments have been set up in order to study the interaction of 193-nm laser radiation with dielectric thin films. At room temperature, Al2O3 coatings show photoluminescence upon ArF excimer laser irradiation, with significant intensity contributions besides the known substrate emission. Time- and energy-resolved measurements indicate the presence of oxygen-defect centers in Al2O3 coatings, which suggests a strong single-photon interaction at 193nm by F+ and F center absorption. Measurements on highly reflective thin-film stacks, consisting of quarter-wave Al2O3 and SiO2 layers, indicate similar UV excitations, mainly from color centers of Al2O3.