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Articles 481 - 488 of 488

Full-Text Articles in Physics

Nuclear-Magnetic-Resonance Measurement Of The Conduction-Electron G Factor In Cdte, David C. Look, D. L. Moore May 1972

Nuclear-Magnetic-Resonance Measurement Of The Conduction-Electron G Factor In Cdte, David C. Look, D. L. Moore

Physics Faculty Publications

The effective g factor g* of conduction electrons in degenerate CdTe has been determined by using measurements of the Cd113 nuclear spin-lattice relaxation time T1 and the Knight shift K. It is shown that the magnitude of g* is given by the Korringa product T1TK2=C(g*)2, where C is a known constant and T is the absolute temperature, and that the sign of g* is given by the sign of K for a spherically symmetric conduction band. The measured value, g*=-1.1±0.1, is within the range allowed …


Nuclear-Magnetic-Resonance Studies Of The Semiconductor-To-Metal Transition In Chlorine-Doped Cadmium Sulfide, Frank D. Adams, David C. Look, Carlton L. Brown, Donald R. Locker Oct 1971

Nuclear-Magnetic-Resonance Studies Of The Semiconductor-To-Metal Transition In Chlorine-Doped Cadmium Sulfide, Frank D. Adams, David C. Look, Carlton L. Brown, Donald R. Locker

Physics Faculty Publications

Spin-lattice relaxation times (T1) and Knight shifts were measured for Cd113 nuclei in 12 CdS crystals doped with various amounts of chlorine. Hall coefficients were measured in order to estimate conduction-electron concentrations. Data were obtained for all samples at 300 °K and for some highly doped samples at 77, 4.2, and 2.13 °K. Metallic properties were observed in all samples having electron concentrations n>2×1018 cm-3. At 300 °K, we find 1/T1∝n for nonmetallic samples and 1/T1∝n2/3 when samples are metallic. The latter proportionality continues to hold at lower …


Nuclear Magnetic Resonance Investigation Of The Metal-To-Semiconductor Transition In Crystalline Cdo, R. P. Benedict, David C. Look Dec 1970

Nuclear Magnetic Resonance Investigation Of The Metal-To-Semiconductor Transition In Crystalline Cdo, R. P. Benedict, David C. Look

Physics Faculty Publications

Measurements of the Cd113 nuclear-spin-lattice relaxation time (T1) and resonance frequency shift (K) were carried out in several samples of polycrystalline n-type CdO over the temperature (T) range 1.4-300°K, frequency (ν) range 2-10 MHz, and carrier concentration (Ne) range 3.3-44×1018 cm-3. For Ne>1019 cm-3, we find that T1∝Ne-2/3T-1 and K∝Ne1/3, showing that the nuclei are interacting with degenerate conduction electrons. Furthermore, the Korringa relationship holds and the calculated electron density at a nucleus is almost the same as …


Time Saving In Measurement Of Nmr And Epr Relaxation Times, David C. Look, Donald R. Locker Feb 1970

Time Saving In Measurement Of Nmr And Epr Relaxation Times, David C. Look, Donald R. Locker

Physics Faculty Publications

By producing a train of absorption or dispersion signals (continuous‐wave magnetic resonance) or free induction decays (pulsed magnetic resonance) it is possible to save time in spin‐lattice relaxation measurements due to the fact that it is not necessary to wait for equilibrium magnetization before initiating the train. The relaxation time may be calculated from the train according to a simple rapidly converging iteration.


Nmr Determination Of The Conduction-Electron Hyperfine Interaction In Crystalline Cdo, David C. Look Aug 1969

Nmr Determination Of The Conduction-Electron Hyperfine Interaction In Crystalline Cdo, David C. Look

Physics Faculty Publications

Measurements of the Cd113 nuclear-spin-lattice relaxation time T1 and Hall effect in crystalline CdO, a degenerate semiconductor, have yielded the contact hyperfine strength of the conduction electrons at the nuclei. The product T1T=168 sec °K, independent of temperature T and frequency ν for T=1.4,4.2, and 77-350 °K, and for ν=2-10 MHz. Taking the carrier concentration N=2.6×1019 cm-3 independent of temperature to within 3% at 4.2, 77, and 300°K, and using an effective electron mass me*=0.2me, we calculate an averaged electron probability density at the nucleus, 〈|φF(0)|2 …


Pulsed Nmr By Tone-Burst Generation, David C. Look, Donald R. Locker Mar 1969

Pulsed Nmr By Tone-Burst Generation, David C. Look, Donald R. Locker

Physics Faculty Publications

No abstract provided.


Measurement Of Electron Spin-Lattice Relaxation Times Using Ordinary Epr Spectrometers, David C. Look, Donald R. Locker Dec 1968

Measurement Of Electron Spin-Lattice Relaxation Times Using Ordinary Epr Spectrometers, David C. Look, Donald R. Locker

Physics Faculty Publications

No abstract provided.


Nuclear Spin-Lattice Relaxation Measurements By Tone-Burst Modulation, David C. Look, Donald R. Locker Jan 1968

Nuclear Spin-Lattice Relaxation Measurements By Tone-Burst Modulation, David C. Look, Donald R. Locker

Physics Faculty Publications

No abstract provided.