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Title: Nuclear magnetic relaxation of /sup 3/He gas. I. Pure /sup 3/He

Abstract

Longitudinal relaxation times T/sub 1/ have been measured in /sup 3/He gas, using pulsed NMR, for number densities between 3 /times/ 10/sup 23/ and 6 /times/ 10/sup 25/ spins m/sup /minus/3/ and temperatures between 0.6 and 15 K. Relaxation takes place on or near the walls of the Pyrex sample cells and measurements of T/sub 1/ give information about the surface phases. A cryogenic wall coating of solid molecular hydrogen was found to delay the formation of a /sup 3/He monolayer on cooling, and T/sub 1/ measurements were consistent with a binding energy of approx. 13 K for a /sup 3/He atom to a hydrogen surface. At temperatures below approx. 2 K a completed /sup 3/He monolayer forms on the H/sub 2/ coating. No variation of the areal density of monolayer completion with bulk number density at fixed temperature could be observed and the completed /sup 3/He monolayer is thought to be a dense fluid. Baking the Pyrex sample cells under vacuum and using an rf discharge in /sup 3/He gas to clean the walls before sealing in the sample gas were found to increase the observed T/sub 1/'s by up to three orders of magnitude. Once a /sup 3/Hemore » monolayer has formed on the H/sub 2/ surface in these cleaned, sealed cells, the dipolar interaction between adsorbed spins is thought to be the dominant source of longitudinal relaxation. The data are consistent with a dipolar relaxation model with a correlation time of approx. 2 /times/ 10/sup /minus/9/ sec. This time is long compared to the value of 10/sup /minus/11/ or 10/sup /minus/12/ sec in the 3D fluid. This suggests that if the surface phase is a 2D fluid and the dipolar mechanism is indeed the dominant one, then the atoms in the 2D fluid are less mobile than in three dimensions. This is consistent with recent susceptibility measurements.« less

Authors:
; ;
Publication Date:
Research Org.:
Univ. of Sussex, Brighton (England)
OSTI Identifier:
5898002
Resource Type:
Journal Article
Journal Name:
J. Low Temp. Phys.; (United States)
Additional Journal Information:
Journal Volume: 72:1-2
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; HELIUM 3; NUCLEAR MAGNETIC RESONANCE; ADSORPTION; BENCH-SCALE EXPERIMENTS; BINDING ENERGY; CORRELATION FUNCTIONS; CRYOSTATS; DENSITY; DEPOSITION; HYDROGEN; J-J COUPLING; LARMOR PRECESSION; MAGNETIC FIELDS; MAGNETIC SUSCEPTIBILITY; NMR SPECTRA; PYREX; RELAXATION TIME; SPIN-LATTICE RELAXATION; SPIN-SPIN RELAXATION; THERMODYNAMICS; TWO-DIMENSIONAL CALCULATIONS; ULTRALOW TEMPERATURE; BOROSILICATE GLASS; CONTROL EQUIPMENT; COUPLING; ELEMENTS; ENERGY; EQUIPMENT; EVEN-ODD NUCLEI; FUNCTIONS; GLASS; HELIUM ISOTOPES; INTERMEDIATE COUPLING; ISOTOPES; LIGHT NUCLEI; MAGNETIC PROPERTIES; MAGNETIC RESONANCE; NONMETALS; NUCLEI; PHYSICAL PROPERTIES; PRECESSION; RELAXATION; RESONANCE; SORPTION; SPECTRA; STABLE ISOTOPES; THERMOSTATS; 640460* - Fluid Physics- Other Quantum Fluids; 656002 - Condensed Matter Physics- General Techniques in Condensed Matter- (1987-)

Citation Formats

Lusher, C P, Secca, M F, and Richards, M G. Nuclear magnetic relaxation of /sup 3/He gas. I. Pure /sup 3/He. United States: N. p., 1988. Web. doi:10.1007/BF00681726.
Lusher, C P, Secca, M F, & Richards, M G. Nuclear magnetic relaxation of /sup 3/He gas. I. Pure /sup 3/He. United States. https://doi.org/10.1007/BF00681726
Lusher, C P, Secca, M F, and Richards, M G. 1988. "Nuclear magnetic relaxation of /sup 3/He gas. I. Pure /sup 3/He". United States. https://doi.org/10.1007/BF00681726.
@article{osti_5898002,
title = {Nuclear magnetic relaxation of /sup 3/He gas. I. Pure /sup 3/He},
author = {Lusher, C P and Secca, M F and Richards, M G},
abstractNote = {Longitudinal relaxation times T/sub 1/ have been measured in /sup 3/He gas, using pulsed NMR, for number densities between 3 /times/ 10/sup 23/ and 6 /times/ 10/sup 25/ spins m/sup /minus/3/ and temperatures between 0.6 and 15 K. Relaxation takes place on or near the walls of the Pyrex sample cells and measurements of T/sub 1/ give information about the surface phases. A cryogenic wall coating of solid molecular hydrogen was found to delay the formation of a /sup 3/He monolayer on cooling, and T/sub 1/ measurements were consistent with a binding energy of approx. 13 K for a /sup 3/He atom to a hydrogen surface. At temperatures below approx. 2 K a completed /sup 3/He monolayer forms on the H/sub 2/ coating. No variation of the areal density of monolayer completion with bulk number density at fixed temperature could be observed and the completed /sup 3/He monolayer is thought to be a dense fluid. Baking the Pyrex sample cells under vacuum and using an rf discharge in /sup 3/He gas to clean the walls before sealing in the sample gas were found to increase the observed T/sub 1/'s by up to three orders of magnitude. Once a /sup 3/He monolayer has formed on the H/sub 2/ surface in these cleaned, sealed cells, the dipolar interaction between adsorbed spins is thought to be the dominant source of longitudinal relaxation. The data are consistent with a dipolar relaxation model with a correlation time of approx. 2 /times/ 10/sup /minus/9/ sec. This time is long compared to the value of 10/sup /minus/11/ or 10/sup /minus/12/ sec in the 3D fluid. This suggests that if the surface phase is a 2D fluid and the dipolar mechanism is indeed the dominant one, then the atoms in the 2D fluid are less mobile than in three dimensions. This is consistent with recent susceptibility measurements.},
doi = {10.1007/BF00681726},
url = {https://www.osti.gov/biblio/5898002}, journal = {J. Low Temp. Phys.; (United States)},
number = ,
volume = 72:1-2,
place = {United States},
year = {Fri Jul 01 00:00:00 EDT 1988},
month = {Fri Jul 01 00:00:00 EDT 1988}
}