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Creator | Title | Description | Subject | Date |
| 176 |
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Mattis, Daniel C. | Few-body problem on a lattice | The author explores some of the inherent simplifications of "quantum lattice physics." He distinguishes between fermions and bosons and analyzes the n-body problem for each, with n = 1,2,3... typically a small number. With delta-function (zero-range) interactions, the three-body problem on a lattice... | Quantum; Electrons; Spin | 1986 |
| 177 |
 |
Symko, Orest George | Discrete spatial filtering with SQUID gradiometers in biomagnetism | First-, second-, and third-order gradiometers used in detecting biomagnetic signals are analyzed as spatial niters. Their transfer functions independent of the source to be measured are presented and both the magnitude and phase characteristics of the transfer functions are analyzed. The distortion ... | Spatial filtering; SQUID gradiometers; Fourier transform | 1986 |
| 178 |
 |
Williams, Clayton C. | Optical ranging by wavelength multiplexed interferometry | A new optical technique is described for measurement of absolute distance. The approach is based upon a wavelength multiplexed heterodyne interferometer with FM demodulation. By temporally multiplexing discrete wavelengths in a heterodyne interferometer, a complete elimination of interferometric ra... | Optical ranging; Distance | 1986 |
| 179 |
 |
Williams, Clayton C. | High resolution thermal microscopy | A new high resolution thermal microscope has been demonstrated capable of imaging thermal fields with sub 1000 angstom resolution. It is based upon a non-contacting near field thermal probe. The thermal probe consists of a thermocouple sensor on the end of a tip with sub 1000 angstrom dimensions. Th... | | 1986 |
| 180 |
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Vardeny, Zeev Valentine | Observation of molecular vibrations in real time | In a recent Letter Rosker, Wise, and Tang1 have reported ultrafast optical measurements on two large dye molecules, malachite green and nile blue 690. Using the transmission-correlation technique with 40-fs light pulses, they measured photoinduced changes in optical transmission and found a resp... | Molecular vibrations; Nile blue 690; Dyes | 1986 |
| 181 |
 |
Vardeny, Zeev Valentine | Optical modulation spectroscopy of a-Si:H based multilayer structures | Steady state optical modulation spectrum of a-Si:H/a-SiNx:H multilayer structure, its temperature dependence and time decay have been studied. For multilayers with very thin sublayers the onset of the spectrum is more gradual and occurs at higher energy than the spectrum for unlayered a-Si:H, indic... | Optical modulation spectroscopy; a-Si:H; Amorphous silicon; Dangling bonds | 1986 |
| 182 |
 |
Williams, Clayton C. | Scanning thermal profiler | A new high-resolution profilometer has been demonstrated based upon a noncontacting nearfield thermal probe. The thermal probe consists of a thermocouple sensor with dimensions approaching 100 nm. Profiling is achieved by scanning the heated sensor above but close to the surface of a solid. The con... | Thermal probe; Scanning thermal profiler | 1986 |
| 183 |
 |
Ailion, David Charles; Morris, Alan H. | Determination of lung water content and distribution by nuclear magnetic resonance imaging | NMR imaging techniques are applicable to the assessment of lung water content and distribution because the NMR signal is, under certain conditions, proportional to tissue proton density. NMR imaging is noninvasive, easily repeatable, free from ionizing radiation, and particularly suitable for the as... | Water content | 1986 |
| 184 |
 |
Symko, Orest George | Spin-glass transition of a dilute Ag-Mn alloy in a magnetic field | The spin-glass state in a magnetic field is studied in a very dilute Ag-Mn sample containing 150 ppm of Mn. The field-cooled magnetization of this system is investigated over temperatures ranging from 4 down to 0.01 K in magnetic fields from 932 to 1 Oe. Scaling is observed in the nonlinear suscepti... | Spin-glass transition; Spin-glass state; Ag-Mn alloy; Silver-manganese alloy | 1986-01 |
| 185 |
 |
Vardeny, Zeev Valentine; Ehrenfreund, Eitan A. | Photogeneration of confined soliton pairs (bipolarons) in polythiophene | From photoinduced absorption and light-induced electron-spin resonance, we demonstrate that the dominant photocarriers generated in polythiophene with excitation above the energy gap (Eg) are charged bipolarons (spin 0). The observation of bipolarons (B2± ) rather than polarons (Pf ) as the dominan... | Photoinduced absorption; Photocarriers; Bipolarons; Photoexcitation | 1986-02 |
| 186 |
 |
Vardeny, Zeev Valentine | Photocarrier dynamics in compensated hydrogenated amorphous silicon | The photocarrier dynamics in compensated a-Si:H is studied using the time-dependent photomodulation technique in the subpicosecond-to-millisecond time range. We find that photocarriers are quickly trapped in shallow impurity levels for t < 10 psec, similar to the behavior in singly doped materials... | Photocarriers; a-Si:H; Amorphous silicon; Fast trapping | 1986-03 |
| 187 |
 |
Symko, Orest George | Spin freezing below the nearest-neighbor percolation concentration in Cd1-xMnxTe and Cd1-xMnxSe | The very-low-temperature magnetization of Cdi_xMnxTe and Cdj-xMnxSe alloys shows spinglass behavior for concentrations below the nearest-neighbor percolation limit. This is attributed to short-range exchange and dipolar interactions. New magnetic phase diagrams for both systems are presented. | Spin freezing; Cd1-xMnxTe; Cd1-xMnxSe; Very-low-temperature magnetization; Spin-glass behavior | 1986-05 |
| 188 |
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Wu, Yong-Shi | Manifestations of Berry's topological phase for the photon | Recently, Berry recognized in quantum mechanics a topological phase factor arising from the adiabatic transport of a system around a closed circuit, which is essentially the Aharonov-Bohm effect in parameter space. Here we consider manifestations of this phase factor for a photon in a state of adia... | Aharonov-Bohm effect; Optical fibers; Waveguide | 1986-08 |
| 189 |
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Vardeny, Zeev Valentine; Ehrenfreund, Eitan A. | Photomodulation spectroscopy of iodine-doped polyacetylene; phase transition from soliton lattice to metal | Using the photomodulation technique for iodine I3-)-doped polyacetylene, we have found spectroscopic evidence for an abrupt phase transition at 5% I3-. The transition is from the lightly doped phase best described as soliton lattice to the heavily doped metallic phase. The phase transition is chara... | Photomodulation spectroscopy; Iodine-doped polyacetylene | 1986-10 |
| 190 |
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DeTar, Carleton | Static screening lengths in the gluon plasma | We report results of an extensive numerical simulation in lattice gauge theory to study various static screening lengths in a finite-temperature pure gluon plasma. Measurements are made for fixed triplet charges (Wilson lines) and a variety of local operators near and above the phase transition for ... | Gluon plasma; Phase transitions; Deconfinement; Strange quarks | 1986-10 |
| 191 |
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Wu, Yong-Shi | Time variation of Newton's gravitational constant in superstring theories | The present time variation of coupling constants in superstring theories with currently favorable internal backgrounds critically depends on the shape of the potential for the size of the internal space. If the potential is almost flat, as in perturbation theory to all orders, the value of G/G for N... | Gravitational constant; Time variation | 1986-10 |
| 192 |
 |
Vardeny, Zeev Valentine; Ehrenfreund, Eitan A. | Detection of soliton shape modes in polyacetylene | We observed soliton shape modes by photoinduced absorption in partially isomerized (CH)x and (CD)x, coexisting with the soliton translational modes. The shape modes' ir activity, their dependence on the degree of isomerization, and the photoinduced spectra are explained in detail by a symmetry-break... | Soliton shape modes; Polyacetylene; Photoinduced absorption | 1986-12 |
| 193 |
 |
Vardeny, Zeev Valentine | Picosecond photomodulation spectroscopy in amorphous semiconductors | Picosecond trapping of photogenerated carriers in gap states of doped, compensated and undoped amorphous hydrogenated silicon (a-Si:H) and of a-Si:H based superlattices was studied by the pump and probe photomodulation technique. In undoped a-Si:H the photogenerated carries are trapped in band-tail ... | Picosecond spectroscopy | 1987 |
| 194 |
 |
Vardeny, Zeev Valentine | Interchain photogeneration of charged solitons in trans-(CH)x | In a recent Letter1 Rothberg, Jedju, Etemad, and Baker (RJEB) used a novel photoinduced-absorption (PA) technique to study charged-soliton (S ?) dynamics in trans-(CH)X with picosecond resolution by measuring transient PA at 0.45 eV. Both intrachain and interchain photogeneration of S ? are rep... | Interchain photogeneration; Charged solitons; Trans-(CH)x | 1987 |
| 195 |
 |
Williams, Clayton C. | Atomic force microscope-force mapping and profiling on a sub 100-Å scale | A modified version of the atomic force microscope is introduced that enables a precise measurement of the force between a tip and a sample over a tip-sample distance range of 30-150Å. As an application, the force signal is used to maintain the tip-sample spacing constant, so that profiling can be ... | Attractive force; Silicon wafer | 1987 |
| 196 |
 |
Vardeny, Zeev Valentine | States in the gap of doped and undoped a-Si:H studied by the photomodulation spectroscopy | The steady state photomodulation spectrum, its temperature and excitation intensity dependences have been studied in phosphorous doped and undoped a-Si:H. The spectra are analyzed in terms of photocarriers trapped in band-tail states and dangling bonds (DB) defects in undoped samples and impurities ... | Doped a-Si:H; Undoped a-Si:H; Amorphous silicon; Photomodulation spectroscopy; Mobility gap; Steady state photomodulation spectrum | 1987 |
| 197 |
 |
Symko, Orest George | Spatial Fourier transform method for evaluating SQUID gradiometers | A simple method of measuring the spatial transfer function of a gradiometer, consisting of a flux transformer coupled to a SQUID, is presented and it is compared with theoretical predictions. Based, on this approach, a new method of reporting a gradiometer's performance is proposed; the rejection fa... | Spatial Fourier transform; SQUID gradiometers; Evaluation; Spatial transfer function | 1987 |
| 198 |
 |
Mattis, Daniel C. | Theory of glass dynamics: the low-lying modes of anharmonic materials | We study the lowest-lying excited states of arbitrary anharmonic solids (crystalline, glassy, or amorphous). Defining the harmonic ("skeleton") lattice underlying any such anharmonic medium, we find that its spectrum of elementary excitations provides a rigorous upper bound to that of the anharmonic... | Spectrum; Arbitrary; Lattices | 1987 |
| 199 |
 |
Mattis, Daniel C. | Bond asymmetry and high-Tc superconductivity | We propose a simple mechanism, anchored in weak-coupling BCS theory, which ties together the following facts: high Tc; quasi two dimensionality; orthorhombic distortion and/or disordered lines of oxygen; proximity to a metal-insulator transition; and anomalously small isotope effects. | Distortion; Singularity; Oxygen | 1987 |
| 200 |
 |
DeTar, Carleton | Thermodynamic properties of the gluon plasma | We calculate the energy density, pressure, and speed of sound in the deconfined phase of lattice SU(3) gauge theory at finite temperature for lattices of temporal size N,=4, 6, and 8. We compare our results with perturbative QCD at high temperature and with a simple phenomenological model. We also p... | Hadronic matter; Energy density; Gluon plasma; Phase transitions | 1987-01 |
