Abstract : This final report describes fundamental surface chemistry studies of photoluminescent metal oxide nanoparticles, toward the goal of demonstrating that changes in photoluminescence (PL) may be correlated to adsorption. One application of this research is the use of PL as a residual life indicator for air filtration media. In addition to adsorption studies on metal oxide nanoparticles, experiments were also carried out on well-defined single crystal surfaces. Research focused on exposure of nanoparticulate zinc oxide, cerium oxide, tungsten oxide, and zirconium hydroxide to hydrogen chloride, sulfur dioxide, and nitrogen dioxide gases. Experiments were also performed with methanethiol. Correlation of PL measurements with surface science experiments demonstrated the feasibility of using fluorescence as an indicator of adsorption. It was demonstrated that sulfur dioxide at concentrations lower than 35 ppm may be detected by monitoring the PL of zinc oxide during gas exposure.