The calculation of ESR spectrum of Mn2+ ions in polycrystalline samples

A program is composed to simulate the ESR spectra of Mn2+ ions (S = 5/2, J = 5/2) in polycrystalline samples at X- and Q-band frequencies taking into account nonvanishing HFS eigenwidth and the 3-rd order terms of perturbation theory for cubic crystalline field with a small axial distortion (D ≪ g β H). Only the lines of allowed transitions (ΔM = ± 1, Δm = 0) have been considered. The probability of various HFS transitions was assumed to be the same and independent of orientation. The resonance field value Hm(θ) was determined for every component. The form of the ESR spectrum of the Mn2+ ion in a polycrystalline sample was found to depend strongly on interrelations between ΔHi, D, and H0. The analysis of the calculated spectra permits to estimate the value of D. A comparison was made between the calculated and experimental spectra of Mn2+ ion in powdered calcite. The theoretical spectrum with the parameters A = −93.5 Oe, D = 85.5 Oe, and Δ Hi, = 2.5 Oe was found to show all the peculiarities of the experimental spectrum.