The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics

, Volume 38, Issue 3, pp 427–438

Paramagnetic relaxation of spin polarized 3He at bare glass surfaces

Part I
  • J. Schmiedeskamp
  • W. Heil
  • E. W. Otten
  • R. K. Kremer
  • A. Simon
  • J. Zimmer
Atomic Physics

DOI: 10.1140/epjd/e2006-00050-2

Cite this article as:
Schmiedeskamp, J., Heil, W., Otten, E. et al. Eur. Phys. J. D (2006) 38: 427. doi:10.1140/epjd/e2006-00050-2

Abstract.

In this first in a series of three papers on wall relaxation of spin polarized, gaseous 3He we investigate both by theory and by experiment surface-induced spin relaxation due to paramagnetic sites in the containing glass. We present experimental and theoretical evidence that — contrary to the traditional opinion — distant dipolar coupling to paramagnetic impurities in the glass, in particular iron ions, cannot be the dominant relaxation mechanism of 3He-spins, although iron dominates the bulk static permeability. Instead dangling-bond type defects in the glass matrix are found to interact much stronger via the isotropic Fermi contact interaction. A model of paramagnetic site controlled 3He relaxation including the Fermi contact interaction is presented. With reasonable semi-empirical assumptions our model allows to describe satisfactorily the measured relaxivities, both in the dissolution-dominated regime of fused silica or borosilicate glasses of the Pyrex type as well as in the surface dominated situation of aluminosilicate glasses which have only a low permeability for He atoms. In a large sample of 1.1 litre cells, built from various aluminosilicate glasses, an average relaxation time of 150 h is reached in case contaminant ferromagnetic particles have been demagnetized beforehand. From the maximum observed value of 250 h we derive after subtraction of dipolar relaxation in the gas phase a paramagnetic surface relaxivity of ρ<0.005 cm/h at room temperature.

PACS.

33.25.+k Nuclear resonance and relaxation34.50.Dy Interactions of atoms and molecules with surfaces; photon and electron emission; neutralization of ions67.65.+z Spin-polarized hydrogen and helium

Copyright information

© EDP Sciences/Società Italiana di Fisica/Springer-Verlag 2006

Authors and Affiliations

  • J. Schmiedeskamp
    • 1
  • W. Heil
    • 1
  • E. W. Otten
    • 1
  • R. K. Kremer
    • 2
  • A. Simon
    • 2
  • J. Zimmer
    • 3
  1. 1.Institut für PhysikMainzGermany
  2. 2.Max-Planck-Institut für FestkörperforschungStuttgartGermany
  3. 3.Schott AGMainzGermany