Observation of collisional de-excitation phenomena in actinide elements

Preprint of the "virtual Workshop on the Atomic Structure of Actinides & Related Topics" conference proceedings submitted to the special issue of Atoms "Atomic Structure of the Heaviest Elements".

In the development context of a gas-cell laser ion source, we report in this article the
observation of prominent phenomena in the laser resonant ionization process specific
to the gaseous environment. In this study we address the significant sensitivity
reduction of a plutonium laser ionization scheme developed in vacuum, which
indicates a strong competition between the laser excitation process and collisional deexcitation
due to the buffer gas atoms. Collisional effects of actinide elements with
noble gasses have been previously reported, especially for low-lying excited states,
nontheless collisional de-excitation effects remain mostly unknown in the excited
states, and are likely enhanced by the very high atomic level density within this region.