Accession Number : AD0291503

Title :   RELAXATION TIME MEASUREMENTS IN RUBY BY A DC MAGNETIZATION TECHNIQUE

Corporate Author : HARVARD UNIV CAMBRIDGE MASS CRUFT LAB

Personal Author(s) : FENG,SHIH-YU

Report Date : 01 JUN 1962

Pagination or Media Count : 1

Abstract : A method of measuring the relaxation time of paramagnetic substances was developed. The change in the z-component of the magnetization was detected by a pick-up coil and the signal was amplified, integrated, and displayed on an oscilloscope. The method was much simpler than any of the other methods, and the reliability of data was, therefore, better. By this technique, the cross-relaxation and the spin-lattice relaxation times were measured for ruby crystals. High-order cross-relaxation processes involving three, four, and five spins were observed, and the relaxation signal could be described fairly well by the solution of a set of rate equations appropriate to the particular process. Spinlattice relaxation times were measured at different temperatures and concentrations. A Bloembergen-Pershan model, involving an inverted Orbach-Wolf mechanism, could satisfactorily explain the observed data. The dependence on concentration, magnetic field strength was also discussed. A qualitative explanation, due to Orbach, was given and the result was compared with the existing data. It seems that there is a mild field dependence, approximately linear with H, at high magnetic fields. (Author)

Descriptors :   *MAGNETIC FIELDS, *PARAMAGNETIC MATERIALS, *PARAMAGNETIC RESONANCE, *RELAXATION TIME, *RUBY, CAVITY RESONATORS

Distribution Statement : APPROVED FOR PUBLIC RELEASE