Study of Li Diffusion on Metal and Semiconductor Surfaces via NQI Presented at the XVth International Symposium on Nuclear Quadrupole Interactions

2000 ◽  
Vol 55 (1-2) ◽  
pp. 15-20
Author(s):  
H. J. Jänsch
Keyword(s):  
Crystal Surface ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
Β Decay ◽  
Spin Lattice ◽  
Quadrupole Interactions ◽  
Nuclear Quadrupole Interactions ◽  
Nuclear Spin Lattice Relaxation ◽  
Relaxation Measurements ◽  
Nuclear Quadrupole

Nuclear magnetic resonance has been used to study the diffusion of lithium on a Ru(001) single crystal surface. The quadrupolar interaction of the radioactive probe nucleus 8Li was utilized for this. In an online experiment the 8Li nuclei are produced, thermalized and highly polarized before they land on the surface studied, the parity violating β-decay revealing the sought after NMR/NQI nuclear information through the spatial asymmetry of the decay electrons. As a function of substrate temperature, alkali metal coverage and magnetic field the nuclear spin-lattice relaxation measurements show the existence of two distinctly different diffusion barriers on the surface, valued at 0.45 eV and 0.15 eV. The former is attributed to jumps from step to terrace sites, whereas the latter is the barrier between adjacent terrace sites. On the substrate Si(l 11)7x7 the relaxation measurements suggest a much higher diffusion barrier around 0.8 eV.

81Br Nuclear Quadrupole Relaxation in Aluminium Tribromide

1995 ◽  
Vol 50 (8) ◽  
pp. 737-741 ◽  
Author(s):  
Noriaki Okubo ◽  
Mutsuo Igarashi ◽  
Ryozo Yoshizaki
Keyword(s):  
Room Temperature ◽  
Lattice Relaxation ◽  
Lattice Relaxation Time ◽  
Spin Lattice Relaxation ◽  
Quadrupole Relaxation ◽  
Spin Lattice ◽  
Raman Process ◽  
Nuclear Spin Lattice Relaxation ◽  
Nuclear Quadrupole ◽  
Nuclear Quadrupole Relaxation

Abstract The 81Br nuclear spin-lattice relaxation time in AlBr3 has been measured between 8 K and room temperature. The result is analyzed using the theory of the Raman process based on covalency. A Debye temperature of 67.6 K and covalency of 0.070 and 0.072 for terminal and 0.022 for bridging bonds are obtained. The correspondence of the latter values to those obtained from the NQR frequencies is low, in contrast to the previously examined compounds.

Segmental Diffusion in Rubbers Studied by Neutron Quasielastic Incoherent Scattering

1974 ◽  
Vol 47 (5) ◽  
pp. 1127-1135
Author(s):  
Geoffrey Allen ◽  
J. S. Higgins ◽  
C. J. Wright
Keyword(s):  
Lattice Relaxation ◽  
Activation Energies ◽  
Spin Lattice Relaxation ◽  
Self Diffusion ◽  
Spin Lattice ◽  
Nuclear Spin Lattice Relaxation ◽  
Relaxation Measurements ◽  
Poly Ethylene Oxide ◽  
Poly Ethylene ◽  
Poly Propylene

Abstract Neutron scattering experiments on polymethylphenylsiloxane, poly(propylene oxide), poly(isobutylene), and poly(ethylene oxide) show broadening in the quasi-elastic region similar to that previously reported from polydimethylsiloxane. Measurements on partially deuterated samples confirm that the effect arises from segmental diffusive motion, rather than rotations of pendent side groups. The temperature dependence of this motion gives activation energies which are smaller than the activation energies for self-diffusion obtained from experiments of longer time-scale such as nuclear spin-lattice relaxation measurements and viscometry.

Nuclear Spin-Lattice Relaxation of a Spin System with Strong Heteronuclear Magnetic Interaction

1996 ◽  
Vol 51 (5-6) ◽  
pp. 710-712
Author(s):  
G. B. Furman ◽  
E. M. Kunoff ◽  
S. D. Goren
Keyword(s):  
Magnetic Interaction ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
Spin Lattice ◽  
Dipole Interactions ◽  
Kinetic Coefficients ◽  
Nuclear Spin Lattice Relaxation ◽  
Quadrupole Resonance ◽  
Different Types ◽  
Nuclear Quadrupole

Abstract Results are presented of a theroretical consideration of the nuclear quadrupole resonance and spin-lattice relaxation for a sample containing nuclei of two different types coupled by strong heteronuclear dipole-dipole interactions and influenced by an external continuous or pulsed ra-diofrequency magnetic field acting only on the nuclei of one sort with spin I > 1/2. A kinetic equation is obtained from which the time dependence of the magnetization of the sample is derived. The kinetic coefficients are calculated as a function of the concentration and distribution of the nuclei of both sorts.

Nucleus-Carrier Interactions in the Group V Semimetals: Dependence on Temperature and Pressure

1992 ◽  
Vol 47 (1-2) ◽  
pp. 49-53 ◽  
Author(s):  
J. M. Keartland ◽  
I. P. Goudemond ◽  
G. C. K. Fölscher ◽  
M. J. R. Hoch
Keyword(s):  
Fermi Surface ◽  
Lattice Relaxation ◽  
Lattice Relaxation Time ◽  
Spin Lattice Relaxation ◽  
Relaxation Data ◽  
Group V ◽  
Spin Lattice ◽  
Nuclear Spin Lattice Relaxation ◽  
Relaxation Measurements ◽  
Temperature And Pressure

AbstractA review is given of pulsed NQR spin-lattice relaxation measurements on the rhombohedral semimetals, arsenic (As) and antimony (Sb). The nuclear spin-lattice relaxation time T1 has been measured in the temperature range 100 mK-600 K. The data follow the Korringa relation at low temperatures, but deviations from this relation are found as the temperature is increased. The results are quantitatively explained by considering interactions of the nuclei with the carriers at the Fermi surface. Above the Debye temperature (θD) the data may be understood by including a two phonon process in the analysis. The relaxation data for As and Sb are found to scale with θD. T1 has been measured for As at 295 K in the pressure range 0 - 10 kbar. The results are discussed in terms of changes in the Fermi surface parameters.

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