Nuclear longitudinal relaxation in hcp D2

F. Weinhaus, S. M. Myers, B. Maraviglia, H. Meyer

Research output: Contribution to journalArticle

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Abstract

We present a systematic study of longitudinal nuclear relaxation times T1 in hcp D2 between 0.4 °K and the triple point, about 18.7 °K, at a frequency of 4.7 MHz. The concentration range of the para molecules (i.e., those with a rotational angular momentum J=1) was between C=0. 02 and C=0. 91. Following saturation, the recovery of the longitudinal magnetization was observed to be exponential as a function of time for all concentrations, and hence the relaxation time T1 was always well defined. In the region below 11 °K, where thermally activated diffusion is "frozen out," the main relaxation mechanisms are by means of the modulation of the intramolecular dipolar fields by the intermolecular electric quadrupole-quadrupole interaction, and by cross relaxation between the nuclei of molecules with J=0 (ortho D2) and J=1 (para D2). The agreement between the limiting high-temperature value T1 and that calculated from theory is good at high concentrations of (J=1) molecules, but only fair at low concentrations. For the latter region, systematic discrepancies between experiment and theory are discussed. The strong temperature dependence of T1 below 4°K is not well understood. In the region above about 12 °K, where diffusion narrows the linewidth, and for concentrations C above about 0.3, the relaxation time T1 is hardly affected by diffusion and shows only a small increase with T. However, T1 for low (J=1) concentrations shows a strong increase with T and a maximum near 17 °K. This behavior can be understood in terms of a theory by Bloom, which was applied to the similar case of solid HD with H2 impurities. At temperature above 13 °K, T1 becomes influenced by diffusion, and the data could be quantitatively fitted to Bloom's theory using two parameters with values close to those estimated theoretically.

Original languageEnglish
Pages (from-to)626-634
Number of pages9
JournalPhysical Review B
Volume3
Issue number3
DOIs
Publication statusPublished - 1971

Fingerprint

Relaxation time
relaxation time
Molecules
quadrupoles
Angular momentum
molecules
nuclear relaxation
cross relaxation
Linewidth
Temperature
Magnetization
Modulation
Impurities
low concentrations
Recovery
angular momentum
recovery
saturation
modulation
impurities

ASJC Scopus subject areas

  • Condensed Matter Physics

Cite this

Weinhaus, F., Myers, S. M., Maraviglia, B., & Meyer, H. (1971). Nuclear longitudinal relaxation in hcp D2. Physical Review B, 3(3), 626-634. https://doi.org/10.1103/PhysRevB.3.626

Nuclear longitudinal relaxation in hcp D2. / Weinhaus, F.; Myers, S. M.; Maraviglia, B.; Meyer, H.

In: Physical Review B, Vol. 3, No. 3, 1971, p. 626-634.

Research output: Contribution to journalArticle

Weinhaus, F, Myers, SM, Maraviglia, B & Meyer, H 1971, 'Nuclear longitudinal relaxation in hcp D2', Physical Review B, vol. 3, no. 3, pp. 626-634. https://doi.org/10.1103/PhysRevB.3.626
Weinhaus F, Myers SM, Maraviglia B, Meyer H. Nuclear longitudinal relaxation in hcp D2. Physical Review B. 1971;3(3):626-634. https://doi.org/10.1103/PhysRevB.3.626
Weinhaus, F. ; Myers, S. M. ; Maraviglia, B. ; Meyer, H. / Nuclear longitudinal relaxation in hcp D2. In: Physical Review B. 1971 ; Vol. 3, No. 3. pp. 626-634.
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AB - We present a systematic study of longitudinal nuclear relaxation times T1 in hcp D2 between 0.4 °K and the triple point, about 18.7 °K, at a frequency of 4.7 MHz. The concentration range of the para molecules (i.e., those with a rotational angular momentum J=1) was between C=0. 02 and C=0. 91. Following saturation, the recovery of the longitudinal magnetization was observed to be exponential as a function of time for all concentrations, and hence the relaxation time T1 was always well defined. In the region below 11 °K, where thermally activated diffusion is "frozen out," the main relaxation mechanisms are by means of the modulation of the intramolecular dipolar fields by the intermolecular electric quadrupole-quadrupole interaction, and by cross relaxation between the nuclei of molecules with J=0 (ortho D2) and J=1 (para D2). The agreement between the limiting high-temperature value T1 and that calculated from theory is good at high concentrations of (J=1) molecules, but only fair at low concentrations. For the latter region, systematic discrepancies between experiment and theory are discussed. The strong temperature dependence of T1 below 4°K is not well understood. In the region above about 12 °K, where diffusion narrows the linewidth, and for concentrations C above about 0.3, the relaxation time T1 is hardly affected by diffusion and shows only a small increase with T. However, T1 for low (J=1) concentrations shows a strong increase with T and a maximum near 17 °K. This behavior can be understood in terms of a theory by Bloom, which was applied to the similar case of solid HD with H2 impurities. At temperature above 13 °K, T1 becomes influenced by diffusion, and the data could be quantitatively fitted to Bloom's theory using two parameters with values close to those estimated theoretically.

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