Spin-lattice relaxation in the alkaline earth hexaammines

M. J. Mobley, W. S. Glaunsinger, R. F. Marzke

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

The proton spin-lattice relaxation times T1 of Ca(NH3)6, Sr(NH3)6, and Ba(NH3)6 have been measured at 8 MHz in the range 30-200 K by using standard pulsed NMR techniques. Dispersed samples were prepared from ingots of the compounds and were mixed with alumina powder to ensure electrical isolation of the metal grains. The samples exhibited T1 behavior differing significantly from that of ammonia. Three different mechanisms for nuclear relaxation appear to operate in this temperature range: (1) rotational diffusion of ammonia at high temperatures (above ∼100 K), (2) activated rotation of ammonia about the pseudo C3 axis in the intermediate temperature range (∼50-100 K), and (3) rotational tunneling which results in temperature independent T1 values in the low temperature range (below ∼50 K). Activation barriers to ammonia diffusion and rotation were determined. Nonexponential relaxation was observed in the vicinity of the T1 minima. These samples exhibited asymmetrical line shapes expected of metal powders with an average particle size somewhat larger than their skin depths. Knight shifts in the narrow line region were determined to be less than 10 ppm, in agreement with recent measurements by cw techniques. The line widths also agreed, to within experimental error, with previously published cw data.

Original languageEnglish (US)
Pages (from-to)1129-1133
Number of pages5
JournalJournal of Physical Chemistry
Volume84
Issue number10
StatePublished - 1980

Fingerprint

Spin-lattice relaxation
spin-lattice relaxation
ammonia
Ammonia
Earth (planet)
nuclear relaxation
Temperature
metal powder
nuclear magnetic resonance
ingots
Aluminum Oxide
Powder metals
temperature
line shape
isolation
Ingots
aluminum oxides
Linewidth
relaxation time
Powders

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

Cite this

Mobley, M. J., Glaunsinger, W. S., & Marzke, R. F. (1980). Spin-lattice relaxation in the alkaline earth hexaammines. Journal of Physical Chemistry, 84(10), 1129-1133.

Spin-lattice relaxation in the alkaline earth hexaammines. / Mobley, M. J.; Glaunsinger, W. S.; Marzke, R. F.

In: Journal of Physical Chemistry, Vol. 84, No. 10, 1980, p. 1129-1133.

Research output: Contribution to journalArticle

Mobley, MJ, Glaunsinger, WS & Marzke, RF 1980, 'Spin-lattice relaxation in the alkaline earth hexaammines', Journal of Physical Chemistry, vol. 84, no. 10, pp. 1129-1133.
Mobley MJ, Glaunsinger WS, Marzke RF. Spin-lattice relaxation in the alkaline earth hexaammines. Journal of Physical Chemistry. 1980;84(10):1129-1133.
Mobley, M. J. ; Glaunsinger, W. S. ; Marzke, R. F. / Spin-lattice relaxation in the alkaline earth hexaammines. In: Journal of Physical Chemistry. 1980 ; Vol. 84, No. 10. pp. 1129-1133.
@article{b81d8e5df4c74429b6b814f801188783,
title = "Spin-lattice relaxation in the alkaline earth hexaammines",
abstract = "The proton spin-lattice relaxation times T1 of Ca(NH3)6, Sr(NH3)6, and Ba(NH3)6 have been measured at 8 MHz in the range 30-200 K by using standard pulsed NMR techniques. Dispersed samples were prepared from ingots of the compounds and were mixed with alumina powder to ensure electrical isolation of the metal grains. The samples exhibited T1 behavior differing significantly from that of ammonia. Three different mechanisms for nuclear relaxation appear to operate in this temperature range: (1) rotational diffusion of ammonia at high temperatures (above ∼100 K), (2) activated rotation of ammonia about the pseudo C3 axis in the intermediate temperature range (∼50-100 K), and (3) rotational tunneling which results in temperature independent T1 values in the low temperature range (below ∼50 K). Activation barriers to ammonia diffusion and rotation were determined. Nonexponential relaxation was observed in the vicinity of the T1 minima. These samples exhibited asymmetrical line shapes expected of metal powders with an average particle size somewhat larger than their skin depths. Knight shifts in the narrow line region were determined to be less than 10 ppm, in agreement with recent measurements by cw techniques. The line widths also agreed, to within experimental error, with previously published cw data.",
author = "Mobley, {M. J.} and Glaunsinger, {W. S.} and Marzke, {R. F.}",
year = "1980",
language = "English (US)",
volume = "84",
pages = "1129--1133",
journal = "Journal of Physical Chemistry",
issn = "0022-3654",
publisher = "American Chemical Society",
number = "10",

}

TY - JOUR

T1 - Spin-lattice relaxation in the alkaline earth hexaammines

AU - Mobley, M. J.

AU - Glaunsinger, W. S.

AU - Marzke, R. F.

PY - 1980

Y1 - 1980

N2 - The proton spin-lattice relaxation times T1 of Ca(NH3)6, Sr(NH3)6, and Ba(NH3)6 have been measured at 8 MHz in the range 30-200 K by using standard pulsed NMR techniques. Dispersed samples were prepared from ingots of the compounds and were mixed with alumina powder to ensure electrical isolation of the metal grains. The samples exhibited T1 behavior differing significantly from that of ammonia. Three different mechanisms for nuclear relaxation appear to operate in this temperature range: (1) rotational diffusion of ammonia at high temperatures (above ∼100 K), (2) activated rotation of ammonia about the pseudo C3 axis in the intermediate temperature range (∼50-100 K), and (3) rotational tunneling which results in temperature independent T1 values in the low temperature range (below ∼50 K). Activation barriers to ammonia diffusion and rotation were determined. Nonexponential relaxation was observed in the vicinity of the T1 minima. These samples exhibited asymmetrical line shapes expected of metal powders with an average particle size somewhat larger than their skin depths. Knight shifts in the narrow line region were determined to be less than 10 ppm, in agreement with recent measurements by cw techniques. The line widths also agreed, to within experimental error, with previously published cw data.

AB - The proton spin-lattice relaxation times T1 of Ca(NH3)6, Sr(NH3)6, and Ba(NH3)6 have been measured at 8 MHz in the range 30-200 K by using standard pulsed NMR techniques. Dispersed samples were prepared from ingots of the compounds and were mixed with alumina powder to ensure electrical isolation of the metal grains. The samples exhibited T1 behavior differing significantly from that of ammonia. Three different mechanisms for nuclear relaxation appear to operate in this temperature range: (1) rotational diffusion of ammonia at high temperatures (above ∼100 K), (2) activated rotation of ammonia about the pseudo C3 axis in the intermediate temperature range (∼50-100 K), and (3) rotational tunneling which results in temperature independent T1 values in the low temperature range (below ∼50 K). Activation barriers to ammonia diffusion and rotation were determined. Nonexponential relaxation was observed in the vicinity of the T1 minima. These samples exhibited asymmetrical line shapes expected of metal powders with an average particle size somewhat larger than their skin depths. Knight shifts in the narrow line region were determined to be less than 10 ppm, in agreement with recent measurements by cw techniques. The line widths also agreed, to within experimental error, with previously published cw data.

UR - http://www.scopus.com/inward/record.url?scp=33847086164&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=33847086164&partnerID=8YFLogxK

M3 - Article

VL - 84

SP - 1129

EP - 1133

JO - Journal of Physical Chemistry

JF - Journal of Physical Chemistry

SN - 0022-3654

IS - 10

ER -