This paper reports the results on structural and photoluminescence (PL) properties of thermally evaporated US thin films subjected to 100 MeV Ag+7 ion irradiation. The structure of the pristine and irradiated films was found to be polycrystalline with preferred orientation along the (002) diffraction line of the US hexagonal phase. The films retain their crystallinity upon irradiation indicating structural stability against irradiation. Formation of Cd clusters due to loss in sulfur atoms during irradiation was identified. However, the structural parameters such as grain size, strain and dislocation density have shown significant changes in their values as a result of irradiation. An increase in the grain size from 19.6 nm for pristine to a maximum of 63.1 nm for the irradiated films was estimated. The irradiation caused relaxation in the c-lattice parameter and shrinkage in the full-width at half-maximum (FWHM). The PL spectrum was dominated by red emission band due to loss of sulfur atoms. (c) 2006 Elsevier B.V. All rights reserved.