Initiation of nuclear reactions under laser irradiation of Au nanoparticles in the aqueous solution of Uranium salt

Laser exposure of a suspension of either gold or palladium nanoparticles in aqueous solutions of UO₂Cl₂ of natural isotope abundance was experimentally studied. Picosecond Nd:YAG lasers at peak power of 10¹¹–10¹³ W/cm² at the wavelength of 1.06–0.355 μm were used as well as a visible-range Cu vapor laser at a peak power of 10¹⁰ W/cm². The composition of colloidal solutions before and after laser exposure was analyzed using atomic absorption and gamma spectroscopy in the 0.06–1 MeV range of photon energy. Real-time gamma spectroscopy was used to characterize the kinetics of nuclear reactions during laser exposure. It was found that laser exposure initiated nuclear reactions involving both ²³⁸U and ²³⁵U nuclei via different channels in H₂O and D₂O. The influence of saturation of both the liquid and nanoparticles by gaseous H₂ and D₂ on the kinetics of nuclear transformations was found. Possible mechanisms of observed processes are discussed.