Effects of Finite Lattice Heat Capacity on Spin Lattice Relaxation: Theory and Numerical Analysis, Issues 102-104U.S. Government Printing Office, 1967 - 21 pages The transient magnetic behavior of a paramagnetic substance, after an initial disturbance, is considered theoretically for a variety of situations in which the lattice temperature rises as a result of energy flow from the magnetic (electron spin) system. The relaxation mechanisms considered are the direct process, involving interaction between spins and the resonant-phonon modes, and a T(9) Raman process, involving the remaining phonon modes. It is first assumed that the resonant and remaining modes are strongly coupled to each other, and that the helium bath has been removed (helium temperatures are assumed). Next, the opposite extreme is considered -- that in which the resonant and remaining modes are totally uncoupled; the helium bath is again assumed to have been removed. Two dramatic effects can occur, depending upon initial conditions. One is the rapid decay to saturation from initial inversion, due to an avalanching creation of resonant phonons by the spins. The second is the pronounced inhibition of the subsequent decay, with the spins remaining near saturation. Finally, consideration is given to the case of spins coupled only to the resonant phonons, which in turn are coupled to a constant temperature bath, whether this be the helium or the remaining modes. Recent phonon avalanche experiments are discussed in this context. It is pointed out that such experiments, performed in the absence of a bath, may provide a reliable measurement of inelastic phonon-boundary scattering. |
Common terms and phrases
approximately ASTM ASTM color bath blue Bureau of Standards calibration charts chromaticity coordinates chromaticity difference CIE standard color match color scale color solid color standards color temperature colorimeter colorimetry computed corresponding curves deg² deviation diagram disk dominant wavelength ellipses energy equations equivalent figure 12 figure 17 four printing-ink specimens glass greenish yellow heat capacity helium indicated ISCC-NBS light Lovibond luminous reflectance luminous transmittance magnesium oxide magnetization after initial measurement process metamerism method msec Munsell Book notations Munsell renotation National Bureau nearest chromaticity match Paramagnetic phonon photoelectric Planckian locus purity purple Raman rate relaxation rate Resonant and remaining resonant modes resonant phonons resonant-phonon sec-¹ spectral composition spectral reflectance spectrophotometric spectrum locus spin inversion spin relaxation spin system Spin-lattice relaxation standard observer Ta(t TABLE tion Transient magnetization tristimulus values U.S. DEPARTMENT uncertainty Union color unknown color variability visual weight Yv V Yv
Popular passages
Page 25 - Handbooks — Recommended codes of engineering and industrial practice (including safety codes) developed in cooperation with interested industries, professional organizations, and regulatory bodies. Special Publications...
Page 22 - Orders should be addressed to the Office of Standard Reference Materials, National Bureau of Standards, Washington, DC 20234, and should give the amount, number, and name of the standards requested.
Page 4 - Color consists of the characteristics of light other than spatial and temporal inhomogeneities; light being that aspect of radiant energy of which a human observer is aware through the visual sensations which arise from the stimulation of the retina of the eye.
Page 25 - TECHNICAL NEWS BULLETIN The best single source of information concerning the Bureau's research, developmental, cooperative and publication activities, this monthly publication is designed for the industry-oriented individual whose daily work involves intimate contact with science and technology — for engineers, chemists, physicists, research managers, product-development managers, and company executives.
Page 25 - CLEARINGHOUSE The Clearinghouse for Federal Scientific and Technical Information, operated by NBS, supplies unclassified information related to Government-generated science and technology in defense, space, atomic energy, and other national programs. For further information on Clearinghouse services, write: Clearinghouse US Department of Commerce Springfield, Virginia...
Page 25 - PERIODICALS JOURNAL OF RESEARCH reports National Bureau of Standards research and development in physics, mathematics, and chemistry. Comprehensive scientific papers give complete details of the work, including laboratory data, experimental procédures, and theoretical and mathematical analyses.
Page 25 - Papers of interest primarily to scientists working in these fields. This section covers a broad range of physical and chemical research, with major emphasis on standards of physical measurement, fundamental constants, and properties of matter. Issued six times a year. Annual subscription: Domestic, $9.50; foreign, $11.75*.