Nuclear magnetic relaxation of3He gas. I. Pure3He

Lusher, C. P.; Secca, Mário Forjaz; Richards, M. G.

doi:10.1007/bf00681726

Cited by 15 publications

(25 citation statements)

References 48 publications

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“…[19] between Eqs. (16) and (24), which leads to the inclusion of an extra factor of cosbi cosbi in the matrix element (36). Since the phase shift bi~0 as E -+ 0 for l ) 0 (and for l = 0 in the case of He), the resulting error will increase with increasing temperature.…”

Section: G Comparison With Previous Resultsmentioning

confidence: 95%

“…Once the current density j on the surface of the scattering volume is known, we can calculate Q from (16), and from (15) find the spin-relaxation rate.…”

Section: B Spin Currentsmentioning

confidence: 99%

“…The relaxation of polarized He at low temperatures has received considerable attention [15] because of interest in studying the transport properties of a polarized Fermi gas [16]. Bulk dipolar relaxation has been observed at temperatures from 1.7 to 19 K [17,18].…”

Section: Introductionmentioning

confidence: 99%

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Gaseous−33He magnetic dipolar spin relaxation

et al. 1993

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We derive the nuclear-spin-relaxation rate of gaseous He due to the magnetic-dipole interaction between the He nuclear spins. This dipolar relaxation rate is numerically evaluated for temperatures from 0.1 to 550 K. At room temperature, the relaxation time for a He density of 10 amagats is 74.4 h. We have made a series of high-density (4 -12 amagat) He samples for which nuclear relaxation is limited by the magnetic-dipole interaction. Both our theoretical and experimental results are particularly important for the growing use of He, polarized through spin exchange with optically pumped Rb vapor.PACS number(s): 34.50. Pi, 33.25.Bn, 32.80.Bx

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Section: G Comparison With Previous Resultsmentioning

confidence: 95%

“…Once the current density j on the surface of the scattering volume is known, we can calculate Q from (16), and from (15) find the spin-relaxation rate.…”

Section: B Spin Currentsmentioning

confidence: 99%

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Gaseous−33He magnetic dipolar spin relaxation

et al. 1993

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“…The effect of adsorbed layers on diffusion can also be removed by H 2 and following 4 He surface covering. 28,36 Moreover, variation of the temperature allows one to change the 3 He mfp values in a large range. Therefore aerogels and other porous samples can be studied under a wide range of experimental conditions that are unavailable using gases other than 3 He.…”

Section: à9mentioning

confidence: 99%

Helium-3 gas self-diffusion in a nematically ordered aerogel at low temperatures: enhanced role of adsorption

Kuzmin

Safiullin

Stanislavovas

et al. 2017

Phys. Chem. Chem. Phys.

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We performed 3 He gas diffusion measurements for the first time in a highly porous ordered Al 2 O 3 aerogel sample at a temperature of 4.2 K using a nuclear magnetic resonance field gradient technique.A strong influence of 3 He adsorption in the aerogel on self-diffusion is observed. The classical consideration of adsorptive gas diffusion in mesopores leads to anomalously high tortuosity factors. The application of a more sophisticated model than the simple combination of empirical two-phase diffusion and the Knudsen gas diffusion models is required to explain our results. Anisotropic properties of the aerogel are not reflected in the observed gas diffusion even at low gas densities where the anisotropic Knudsen regime of diffusion is expected. The observed gas densification indicates the influence of the aerogel attractive potential on the molecular dynamics, which probably explains the reduced diffusion process. Perhaps this behavior is common for any adsorptive gases in nanopores.

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“…The adsorption energies of 3 He atoms on these coated walls and the relaxation mechanisms of atoms or adsorbed layers on weakly relaxing substrates have been extensively studied and are well understood (Himbert and Dupont-Roc, 1989; Lefevre-Seguin et al , 1985; Lefevre-Seguin and Brossel, 1988; Lusher et al , 1988a,b). Depending on experimental conditions, different relaxation regimes can be observed.…”

Section: He Relaxationmentioning

confidence: 99%

Optically polarizedHe3

et al. 2017

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This article reviews the physics and technology of producing large quantities of highly spin-polarized 3He nuclei using spin-exchange (SEOP) and metastability-exchange (MEOP) optical pumping. Both technical developments and deeper understanding of the physical processes involved have led to substantial improvements in the capabilities of both methods. For SEOP, the use of spectrally narrowed lasers and K-Rb mixtures has substantially increased the achievable polarization and polarizing rate. For MEOP nearly lossless compression allows for rapid production of polarized 3He and operation in high magnetic fields has likewise significantly increased the pressure at which this method can be performed, and revealed new phenomena. Both methods have benefitted from development of storage methods that allow for spin-relaxation times of hundreds of hours, and specialized precision methods for polarimetry. SEOP and MEOP are now widely applied for spin-polarized targets, neutron spin filters, magnetic resonance imaging, and precision measurements.

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Nuclear magnetic relaxation of3He gas. I. Pure3He

Cited by 15 publications

References 48 publications

Gaseous−33He magnetic dipolar spin relaxation

Gaseous−33He magnetic dipolar spin relaxation

Helium-3 gas self-diffusion in a nematically ordered aerogel at low temperatures: enhanced role of adsorption

Optically polarizedHe3

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