Accession Number : AD0695620

Title :   EXPERIMENTAL MEASUREMENTS OF SHORT SPIN RELAXATION TIMES: HIGH TEMPERATURE RELAXATION PROCESSES OF Fe(+) IN MgO.

Descriptive Note : Technical rept.,

Corporate Author : ARMY MISSILE COMMAND REDSTONE ARSENAL ALA PHYSICAL SCIENCES LAB

Personal Author(s) : Bennett,Jefferson S.

Report Date : 28 AUG 1969

Pagination or Media Count : 133

Abstract : The spin-lattice relaxation time, T(1), for the ground state Kramers doublet of Fe(+) in MgO has been measured by pulse saturation in a fast TWT (traveling wave tube) x-band spectrometer. All the data from 10 to 23K are accurately described by an equation. From 1.2 to about 10K, the relaxation time is angular dependent and there is evidence for cross relaxation. The microwave absorption line is inhomogeneously broadened at 4.2K and is nearly Lorentzian at all temperatures. The observed line width has a relaxation induced component whose temperature dependence from 23.2 to 37K with H is accurately described. Bloch's equations give the ratio T(1)/T(2) 0.73. These measurements establish the existance of sharp electronic levels at about 150/cm and 310/cm above the ground state Kramers doublet on the basis of relaxation via two Orbach processes. The energy level separation is in partial agreement with the predictions of a point charge model of cubic MgO. The alrge reduction of octahedral crystal field parameters indicated by the experimental results is discussed. (Author)

Descriptors :   (*IRON, RELAXATION TIME), (*MAGNESIUM OXIDES, *PARAMAGNETIC MATERIALS), PHONONS, ELECTRON TRANSITIONS, MOLECULAR ENERGY LEVELS, SPINNING(MOTION), INTERACTIONS, PARAMAGNETIC RESONANCE, TRAVELING WAVE TUBES

Subject Categories : Atomic and Molecular Physics and Spectroscopy
      Solid State Physics

Distribution Statement : APPROVED FOR PUBLIC RELEASE