Elektrische Quadrupolwechselwirkungen von²⁰F im MgF₂-Einkristall

verfasst von

H. J. Stöckmann, H. Ackermann, D. Dubbers, M. Grupp, P. Heitjans

Abstract

Polarized²⁰F nuclei (T_1/2=11s, I=2) have been produced in a tetragonal MgF₂ single crystal by capture of polarized neutrons. Nuclear magnetic resonance transitions have been induced and observed via the asymmetric Β decay to²⁰Ne, yielding the quadrupole coupling constant |e²q Q/h|=5.77(2)MHz, the quadrupole moment |Q(²⁰F)|=0.064(12) b and the asymmetry parameter of the electric field gradient η=0.317(2). In order to study possible lattice defects produced by the recoil displacement due to the capture γ-rays NMR signals were registered both at room temperature and at 12 K. Width and depth of the resonance curves indicated that at room temperature nearly all²⁰F ions occupy normal lattice sites with an undisturbed environment. At 12 K, however, where no annealing occurs, this is only true for about half of the²⁰F ions which are stopped directly at defect free sites. The other half of the²⁰F ions at 12 K shows resonance frequencies shifted by defect interactions up to the order of some 100 kHz. Furthermore two simple methods are reported which allow a quick estimate of the strength of the quadrupolar interaction: (1) observation of the Β decay asymmetry versus the magnetic field strength (decoupling curve), (2) broad-band modulation of the induced rf field and observation of the Β asymmetry versus the depth of the modulation.

Externe Organisation(en)

Ruprecht-Karls-Universität Heidelberg

Typ

Artikel

Journal

Zeitschrift für Physik

Band

269

Seiten

47-57

Anzahl der Seiten

11

ISSN

1434-6001

Publikationsdatum

03.1974

Publikationsstatus

Veröffentlicht

Peer-reviewed

Ja

ASJC Scopus Sachgebiete

Kern- und Hochenergiephysik, Physik und Astronomie (insg.)

Elektronische Version(en)

https://doi.org/10.1007/BF01668868 (Zugang: Unbekannt)