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11.
Dale R. Harshman 《Hyperfine Interactions》1986,32(1-4):847-863
The interactions of muonium (μ
+
e
−, Mu) with the surfaces of fine silica powders have been extensively studied using zero, longitudinal and transverse field
μSR techniques. These studies indicate diffusion and trapping behavior of the Mu atoms on the silica surface, which is strongly
influenced by the surface hydroxyl (OH) concentration. Specifically, the presence of the surface OH groups is observed to
inhibit the surface mobility of the Mu atoms at low temperatures. Information provided by zero and longitudinal field data
suggest a random anisotropic distortion of the Mu hyperfine interaction (RAHD) as the principal relaxation mechanism. A recently
developed RAHD spin relaxation theory is used to interpret these data. Additional investigations, using platinum loaded silica,
have yielded the first observed surface reaction of Mu.
Studies of the interactions of positive muons with surfaces have been also extended to single crystals, where low energy (<10
eV)μ
+ andMu
− ions are observed to be reemitted from some materials (e.g., the <100> surface of lithium fluoride). Future applications
of these emission phenomena toward the development of a slow847-3 (or Mu−) beam are considered. 相似文献
12.
Dale R. Harshman Ralph Eric Turner Jess H. Brewer David P. Spencer 《Hyperfine Interactions》1986,32(1-4):527-533
Muonium (μ
+
e
−) in bulk fused quartz is a unique system in that theμ
+ spin polarization (in the muonium state) relaxes almost entirely via random anisotropic hyperfine distortions (RAHD). As
such, this system provides an excellent test case for a new RAHD spin relaxation theory. This theory is quantitatively compared
to static zero field data and the functional characteristics in both the high field and dynamic limits are considered as well. 相似文献
13.
D. R. Harshman R. Keitel M. Senba E. J. Ansaldo J. H. Brewer 《Hyperfine Interactions》1984,18(1-4):557-561
The behavior of muonium on the surface of finely divided silica (amorphous SiO2) powder (mean grain diameter 70 Å) has been studied as a function of the surface concentration of hydroxyl groups. The temperature dependence of the Mu relaxation rate in transverse field was measured for samples prepared with 0%, 50% and 70% of the surface hydroxyl groups removed over the temperature range 4 K <T < 300 K. The relaxation rate shows a distinct maximum at about 25 K and a minimum at about 16 K for all three samples, and shows a dramatic decrease below 16 K as the concentration of surface hydroxyls is reduced. A three-state nonequilibrium model describing the diffusion and trapping of muonium on the silica surface is used to interpret the data.On leave from Department of Physics, University of Saskatchewan, Saskatoon, Sask. S7N OWO, Canada. 相似文献
14.
Normal state resistivity and Hall effect are shown to be successfully modeled by a two-band model of holes and electrons that is applied self-consistently to (i) dc transport data reported for eight bulk-crystal and six oriented-film specimens of YBa2Cu3O7?δ, and (ii) far-infrared Hall angle data reported for YBa2Cu3O7?δ and Bi2Sr2CaCu2O8+δ. The electron band exhibits extremely strong scattering; the extrapolated dc residual resistivity of the electronic component is shown to be consistent with the previously observed excess thermal conductivity and excess electrodynamic conductivity at low temperature. Two-band hole–electron analysis of Hall angle data suggests that the electrons possess the greater effective mass. 相似文献
15.
16.
The reaction rates of muonium with ethylene adsorbed on the surface of amorphous silica powder grains were measured between
6 K and 300 K. kf values characterizing the two-dimensional surface reactions and the 2 1/2 dimensional reactions with muonium in the gas phase
were obtained. 相似文献
17.
Brewer JH Ansaldo EJ Carolan JF Chaklader AC Hardy WN Harshman DR Hayden ME Ishikawa M Kaplan N Keitel R Kempton J Kiefl RF Kossler WJ Kreitzman SR Kulpa A Kuno Y Luke GM Miyatake H Nagamine K Nakazawa Y Nishida N Nishiyama K Ohkuma S Riseman TM Roehmer G Schleger P Shimada D Stronach CE Takabatake T Uemura YJ Watanabe Y Williams DL Yamazaki T Yang B 《Physical review letters》1988,60(11):1073-1076
18.
19.
D.R. Harshman R. Keitel M. Senba R.F. Kiefl E.J. Ansaldo J.H. Brewer 《Physics letters. A》1984,104(9):472-476
The spin relaxation rate λMu of muonium atoms on fine silica powder surfaces was measured as a function of temperature and of the surface concentration of hydroxyl groups. Results indicate two-dimensional diffusion, trapping and detrapping of the muonium atoms on the silica surface. At low temperatures λMu decreases dramatically as the concentration of surface hydroxyls is reduced. A three-state model is used to extract the muonium adsorption energy and other physical parameters. 相似文献
20.
Luke G. M. Kiefl R. F. Kreitzman S. R. Brewer J. H. Noakes D. R. Celio M. Keitel R. Uemura Y. J. Harshman D. R. Jaccarino V. 《Hyperfine Interactions》1986,31(1-4):29-34
We report the observation of μ+ Level-Crossing Resonances (LCR's) in the ordered phase of an antiferromagnetic material. Two LCR's were observed in MnF2 as a function of longitudinal magnetic field in the temperature range between 10K and 65K. Both are attributed to a muon
in an interstitial octahedral-like site. The low field resonance is attributed to a muon-nuclear spin flip-flop transition
involving the two nearest neighbour19F nuclei. The high field resonance occurs when the applied field cancels the local hyperfine field on the muon. The positions
and widths of the LCR's were seen to scale with the sublattice magnetization. 相似文献