Significant interest in the laser separation of uranium isotopes at the turn of the century stimulated the search for and development of a number of methods and approaches that use both atomic and molecular mechanisms of isotope separation. Effective laser methods for the separation of uranium isotopes are currently under active development in many countries. New approaches to the molecular laser isotope separation (MLIS) of uranium are reviewed. They are based on resonant isotope-selective multiphoton excitation of high vibrational states (2ν₃ and 3ν₃) of ²³⁵UF₆ and ²³⁸UF₆ molecules in gas-dynamically cooled molecular flows by bichromatic IR laser radiation and the subsequent dissociation of the excited molecules by the same laser pulses. The foundations of these approaches are analyzed. The results of experiments on two- and three-photon excitation of SF₆ molecules, whose spectroscopic properties are similar to those of UF₆ molecules, into the 2ν₃ and 3ν₃ vibrational states by, respectively, two- and three-frequency radiation of pulsed CO₂ lasers are presented and discussed. Specific setups and parameters of resonant two- and three-photon isotope-selective excitation of ²³⁵UF₆ and ²³⁸UF₆ molecules into the 2ν₃ and 3ν₃ vibrational states by bichromatic IR radiation from two pulsed CF₄ lasers and two para-H₂ lasers with emissions in the 16-μm region are proposed and analyzed. A method is considered for the isotope-selective excitation and dissociation of UF₆ molecules in a mixture with a sensitizer (SF₆ molecules) under nonequilibrium thermodynamic conditions of a shock wave. Low-energy MLIS methods for uranium based on the proposed approaches are shown to be feasible.

Keywords: atoms, molecules, clusters, uranium, molecular and cluster beams, laser spectroscopy, laser-induced selective processes in molecules and clusters, laser separation of uranium isotopes, laser physics PACS: 07.77.Gx, 28.60.+s, 33.80-b, 36.40.−c, 42.62.−b, 42.62.Fi, 82.50.Bc (all) DOI: 10.3367/UFNe.2023.02.039325 URL: https://ufn.ru/en/articles/2024/1/d/ 001198734600004 2-s2.0-85186577793 2024PhyU...67...44M Citation: Makarov G N "New approaches to molecular laser separation of uranium isotopes" Phys. Usp. 67 44–54 (2024) BibTexBibNote ® (generic)BibNote ® (RIS)MedlineRefWorks Received: 19th, January 2023, revised: 17th, February 2023, accepted: 20th, February 2023 Оригинал: Макаров Г Н «Новые подходы к молекулярному лазерному разделению изотопов урана» УФН 194 48–59 (2024); DOI: 10.3367/UFNr.2023.02.039325