Theory of Paramagnetic Acoustic Resonance Absorption by U⁴⁺ Ions in Cubic Crystalline Field

Abstract

Ultrasonic paramagnetic resonance absorption coefficients by f² ions in a cubic field are calculated with special reference to U⁴⁺ in ThO₂. The UPR absorption coefficients at liquid helium temperature are large and comparable in magnitude to those of lanthanide tons with an even number of electrons, however they drop very rapidly with the elevation of temperature. The tetragonal and the trigonal coupling constants, A_o and B_o, in the orbit-lattice interaction Hamiltonian can be determined independently by measuring the absorption coefficients with longitudinal and transverse waves, respectively. The characteristic angular dependences of absorption coefficients are also discussed.