The formation of colloidal unmodified ('naked') gold nanoparticles is investigated by irradiation of a precursor solution with X-rays from a synchrotron source. An interesting morphological evolution as a function of exposure time, from cross-linked network-like structure to individual particles, has been discovered. The particle size decreased with the exposure time and was influenced by the ionic strength of the precursor solution. Contrary to gamma- ray exposure, an OH radical scavenger was not required for cluster formation.
