Microscopic and spectroscopic analysis of ion-irradiated molecular-plated thin films for superheavy element production

Abstract

The heaviest known elements are produced via fusion reactions by bombarding actinide targets with intense heavy ion beams. The production of actinide targets relies mainly on the molecular plating (MP) technique. Long-term stability of MP produced targets is typically achieved by a conditioning procedure, in which fresh targets are exposed to successively increasing beam intensities. This leads to non-trivial physical and chemical transformations, which are presently poorly understood. To shed light on processes in the initial irradiation stage, we irradiated thin Tm MP films with Cl and Au ions of different fluences, with the latter ranging from 1010 to 1014 , and analyzed their morphology and composition by a variety of microscopic, spectroscopic and ion beam techniques. The study was conducted on lanthanide targets, which serve as non-radioactive analogues for heavy actinide targets. Combining the results of several methods, we conclude that the MP thin films consist of a mixture of carbonates and formates. Under irradiation, these films transform into amorphous oxides with embedded carbon clusters.