A New Zero‐Field Paramagnetic Resonance Spectrometer
The construction of a new zero‐field paramagnetic resonance (ZFPMR) spectrometer is discussed. Spectrometer organization and construction details are presented for both resonant cavities and broadband traveling‐wave helices as sample holders. A new circuit diagram for a square wave magnetic field modulator with fast rise time is given. The performance of each kind of spectrometer is discussed with particular emphasis on investigation of paramagnetic rare earth ions with zero‐field splittings in diamagnetic host lattices.
The paramagnetic resonance spectra of gadolinium and neodymium ethyl sulphates
Accurate measurements of the paramagnetic resonance spectra of gadolinium and neodymium ethyl sulphates have been made both in strong magnetic fields at a wave-length of 3 cm, and in weak fields at wave-lengths between 6 and 22 cm. (i) The Gd3+ ion is in an 8S state, whose levels are split by the action of the crystalline electric field, which is assumed to have C3h symmetry. The results are consistent with this supposition, except for some discrepancies in the position of the zero field lines, whose origin is not certain. The main parameters in the spin Hamiltonian are evaluated, and the spectroscopic splitting factor is found to be isotropic at 1.990±0.002. (ii) The Nd3+ ion is in a 4I2/3 state, which is split by the crystal field leaving a Kramers doublet as the ground state. The hyperfine structure due to the two odd isotopes 143, 145 has been measured and gives the ratio of the nuclear magnetic moments (143/145) as 1.6083±0.0012. Some small discrepancies in the positions of the hyperfine lines in zero field are found, which prevent the determination of accurate values of the nuclear electric quadrupole interaction. The theory of Elliott & Stevens (1953b) leads to values of 1.0 and 0.62 nuclear magnetons for the moments of isotopes 143 and 145 respectively, with an uncertainty of about ±25% arising from lack of a precise value for r–3¯¯¯, where r is the electron-nuclear distance.
A calculation of the ground-state splitting for Mn2+ ions in a cubic field
The ground-state splitting and optical absorption spectrum for a (d5)6S ion in a cubic host crystal are calculated (by means of the simplest crystal field approximation and a complete (d5) configuration) as functions of the Racah parameters B and C, the crystal field parameter ?, the spin-orbit parameter £, and the spin-spin parameters M0 and M2.