Topic
Relaxation (NMR)
About: Relaxation (NMR) is a research topic. Over the lifetime, 29342 publications have been published within this topic receiving 689851 citations.
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TL;DR: In this article, the second-order perturbation of spin-phonon interactions is used to obtain an upper limit of the pre-exponential factor in the Arrhenius law, consistent with the very large experimental value.
Abstract: The relaxation time of the magnetization of a big magnetic molecule is evaluated. Isotropic exchange is assumed to be dominant, resulting in a fixed spin modulus s (equal to 20 in the case of interest). A perturbation of the form ASz2 results from spin-orbit coupling and produces an energy barrier As2 which separates positive and negative values of Sz. Spin-phonon interactions are treated by second-order perturbation theory. An upper limit of the pre-exponential factor in the Arrhenius law is obtained, which is consistent with the very large experimental value.
192 citations
TL;DR: A simple mathematical formalism is presented which allows closed form expressions for the echo attenuation, E(q), in spin echo diffusion experiments, for practically all gradient waveforms and for the case of restricted diffusion in enclosing pores, with or without wall relaxation.
192 citations
TL;DR: All five deuterium relaxation rates have been measured for deuterons in the methyl groups of the B1 immunoglobulin binding domain of peptostreptococcal protein L and the N-terminal SH3 domain from the protein drk.
Abstract: New pulse sequences are presented for the measurement of the relaxation of deuterium double quantum, quadrupolar order, and transverse antiphase magnetization in 13CH2D methyl groups of 15N-, 13C-labeled, fractionally deuterated proteins. Together with previously developed experiments for measuring deuterium longitudinal and transverse decay rates [Muhandiram, D. R.; Yamazaki, T.; Sykes, B. D.; Kay, L. E. J. Am. Chem. Soc. 1995, 117, 11536], these schemes allow measurement of the five unique decay constants of a single deuteron, providing an unprecedented opportunity to investigate side-chain dynamics in proteins. All five deuterium relaxation rates have been measured for deuterons in the methyl groups of the B1 immunoglobulin binding domain of peptostreptococcal protein L and the N-terminal SH3 domain from the protein drk. Since values of the spectral density function at only three different frequencies contribute to the five relaxation rates, the self-consistency of the relaxation data is readily establ...
191 citations
TL;DR: Optical orientation of spin-polarized heavy and light holes followed by relaxation to other valence subband states has been observed unambiguously in undoped bulk GaAs in spite of the extremely short spin relaxation time.
Abstract: Optical orientation of spin-polarized heavy and light holes followed by relaxation to other valence subband states has been observed unambiguously in undoped bulk GaAs in spite of the extremely short spin relaxation time. The measured relaxation time for the heavy holes is 110 fs $\ifmmode\pm\else\textpm\fi{}10%$. The results are relevant for applications such as interpretation of spin-polarized transport in semiconductors as well as the assessment of feasibility of hole-based spin-transport devices which relies on precise knowledge of the hole-spin relaxation time.
191 citations
TL;DR: In this article, the van der Waals liquid orthoterphenyl has been used as a model system in the study of the glass transition and the mode-coupling singularity appears as a change of transport mechanism in the moderately viscous liquid, at temperatures far above the conventional (caloric) glass transition.
Abstract: The van der Waals liquid orthoterphenyl has long been used as a model system in the study of the glass transition. Motivated by mode-coupling theory, extensive experiments have been undertaken to monitor the onset of structural relaxation on microscopic time and length scales. Using in particular quasielastic neutron scattering, the decay of density and tagged-particle correlations has been measured as a function of temperature, pressure and wave number. A consistent picture is developped in which the mode-coupling singularity appears as a change of transport mechanism in the moderately viscous liquid, at temperatures far above the conventional (caloric) glass transition.
190 citations