The zero‐field splitting of the Mo³⁺ ground state in corundum

Abstract

For the first time the ESR of Mo3+ ions in u-A1203 single crystals was investigated in /1/ at the frequency u = 9.25 GHz. From the analysis of ESR spectra followed that the trivalent Mo3+ ions with S = 3/2 isomorphously replace the A13+ions. The corundum crystalline field splits the fourfold degenerate ground state A2 of Mo m two Kramers doublets. However, only the intradoublet transition -1/2 e , +1/2 was observed in the X-band, because of the large zero-field splitting (ZFS) between the doublets. It was also shown that the ESR spectrum of Mo3+ is well described by the axially symmetrical spin-Hamiltonian 4 3 + .where S = 3/2, I = 5/2, the z-axis is parallel to the electric field axis C3. In the same paper a method of determining a l a r g e ZFSvalue 12DI at a single low frequency was proposed. However, the accuracy of measurements of angles and magnetic fields usually does not allow a sufficiently accurate determination of 12DI by this method. 3+ in For precise measurements of ZFS between Kramers doublets of Mo corundum we have undertaken a direct search of interdoublet transitions using the millimeter range ESR spectrometer described in /2/. The samples of dimensions 3x7~10 mm were placed inside the 8 mm waveguide cooled by liquid nitrogen. The concentration of Mo3+ ions in the specimens w a s about 0.001 %. The absorption lines corresponding to the electronic transitions +1/2 e , 9 / 2 were found near 165 GHz. The intensities of ESR lines obtained in different 1) Ashtarak-2, USSR.

Широкополосная Эпр-Спектроскопия Ионов Мо-=sup=-3+-=/Sup=- В Иттрий-Алюминиевом Гранате

“…Наблюдение спектров ЭПР, вызванных междублетными переходами иона молибдена, ранее было сделано в кристалле корунда [8] также с помощью методов высокочастотной ЭПР-спектроскопии. Авторы, измерив прямым методом величину РНП (164.8 GHz), наблюдали частично разрешенную сверхтонкую структуру от нечетных изотопов молибдена, что упростило идентификацию спектров.…”