Irradiation of solids with energetic particles, such as electrons or ions, normally gives rise to the formation of atomic defects in the target and changes the material's properties. However, inspite of the damage, irradiation may overall have a beneficial effect on the target. In the present study, Mn-doped ZnS nanocrystals have been synthesized using an aqueous solution method and irradiated by a C6+ (80MeV) ion beam at fluence (1 × 1013ions/cm2). A photoluminescence study has been carried on in a ZnS:Mn system, which results in emission peaks corresponding to surface states and Mn2+ emission, confirming that optical luminescence in semiconductor nanocrystals can be tuned using impurity concentration as well as swift heavy ion irradiation between nanocrystals band gap and the bulk band gap values. © 2015 © 2015 Taylor & Francis.