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

TL;DR

This study demonstrates that laser irradiation of gold or palladium nanoparticles in uranium salt solutions can initiate nuclear reactions, with real-time gamma spectroscopy revealing different reaction channels and the influence of dissolved gases.

Contribution

It provides experimental evidence of laser-induced nuclear reactions in nanoparticle suspensions containing uranium salts, a novel approach in nuclear chemistry.

Findings

Laser exposure initiates nuclear reactions involving 238U and 235U.

Reaction kinetics are affected by dissolved H2 and D2 gases.

Different laser wavelengths and powers influence reaction pathways.

Abstract

Laser exposure of 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 from 1011 to 1013 W/cm2 at the wavelength of 1064 and 355 nm were used as well as a visible-range Cu vapor laser at peak power of 1010 W/cm2. The composition of colloidal solutions before and after laser exposure was analyzed using atomic absorption and gamma spectroscopy between 0.06 and 1 MeV range of photon energy. A 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.