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Articles 18091 - 18120 of 20470

Full-Text Articles in Physics

Raman Scattering And Lattice-Dynamical Calculations Of Crystalline Kno3, H. M. Lu Jan 1992

Raman Scattering And Lattice-Dynamical Calculations Of Crystalline Kno3, H. M. Lu

John R. Hardy Papers

The Raman spectrum of a KNO3 single crystal was measured at both room and liquid-nitrogen temperatures. Lattice-dynamical calculations, based on the rigid-ion approximation and empirical potentials, were performed. The possibility of a phase transition at 217 K was investigated by measuring the temperature dependence of the Raman spectrum.

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Ultrahigh Vacuum Chamber For Synchrotron X-Ray Diffraction From Films Adsorbed On Single-Crystal Surfaces, Jr Dennison, S. K. Wang, S. N. Ehrlich Jan 1992

Ultrahigh Vacuum Chamber For Synchrotron X-Ray Diffraction From Films Adsorbed On Single-Crystal Surfaces, Jr Dennison, S. K. Wang, S. N. Ehrlich

Journal Articles

An ultrahigh vacuum chamber has been developed for structural analysis of adsorbed films and single-crystal surfaces using synchrotron x-ray diffraction. It is particularly well suited for investigations of physisorbed and other weakly bound films. The chamber is small enough to transport and mount directly on a standard four-axis diffractometer and can also be used independently of the x-ray diffractometer. A low-current, pulse-counting, low-energy electron diffraction/Auger spectroscopy system with a position-sensitive detector enables in situ characterization of the film and substrate while the sample is located at the x-ray scattering position. A closed-cycle He refrigerator and electron bombardment heater provide controlled …

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Lattice- And Molecular-Dynamics Studies Of Phase Transitions In Csliso4, V. Katkanant Jan 1992

Lattice- And Molecular-Dynamics Studies Of Phase Transitions In Csliso4, V. Katkanant

John R. Hardy Papers

We report results of a simulation of the phase transitions in CsLiSO4. These are based on our previously developed method for calculating parameter-free potential-energy surface for ionic molecular crystals. Our lattice-dynamical and molecular-dynamics studies show that the roomtemperature (Pnam) phase is unstable and transforms to the observed low-temperature (P1121/n) phase over approximately 200–280 K. The unstable modes of the Pnam phase have maximum instability at the zone center, which indicates a possible phase transformation without a cell multiplication. The rotational ordering of tetrahedral SOM4 2- was found to be …

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Extrapolation Procedures In Mott Electron Polarimetry, Timothy J. Gay, M. A. Khakoo, J. A. Brand, J. E. Furst, W. V. Meyer, W. M. K. P. Wijayaratna, F. B. Dunning Jan 1992

Extrapolation Procedures In Mott Electron Polarimetry, Timothy J. Gay, M. A. Khakoo, J. A. Brand, J. E. Furst, W. V. Meyer, W. M. K. P. Wijayaratna, F. B. Dunning

Timothy J. Gay Publications

In standard Mott electron polarimetry using thin gold film targets, extrapolation procedures must be used to reduce the experimentally measured asymmetries A to the values they would have for scattering from single atoms. These extrapolations involve the dependence of A on either the gold film thickness t or the maximum detected electron energy loss in the target ΔE. Using a concentric cylindrical-electrode Mott polarimeter, we have studied and compared these two types of extrapolations over the electron energy range 20-100 keV. The potential systematic errors which can result from such procedures are analyzed in detail, particularly with regard to the …

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Production Of A High-Density State-Selected Metastable Neon Beam, J. A. Brand, J. E. Furst, Timothy J. Gay, L. D. Shearer Jan 1992

Production Of A High-Density State-Selected Metastable Neon Beam, J. A. Brand, J. E. Furst, Timothy J. Gay, L. D. Shearer

Timothy J. Gay Publications

We have developed a high-density source of metastable neon and have selectively quenched both metastable species using a standing-wave dye laser. The source is compact, stable, and produces an average intensity of 3.6 x 1014 sr -1 s -1 and a density on target of 7.7 x 106 cm-3.

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An Attempt To Observe Mott Scattering Optically, J. E. Furst, Timothy J. Gay, W. M. K. P. Wijayaratna, K. Bartschat, H. Geesmann, M. A. Khakoo, D. H. Madison Jan 1992

An Attempt To Observe Mott Scattering Optically, J. E. Furst, Timothy J. Gay, W. M. K. P. Wijayaratna, K. Bartschat, H. Geesmann, M. A. Khakoo, D. H. Madison

Timothy J. Gay Publications

We report an attempt to make an optical observation of Matt scattering, involving the first studies of inelastic collisions between polarized electrons and a heavy noble gas. Polarization fractions of light emitted by the 5p56p[5/7],(3D3) state of Xe following impact excitation in an axial collision geometry were measured as a funclion of the incident electron energy, and compared with distorted-wave Bom calculations. The theoretical and experimental results agree qualitatively in the energy range where cascade contributions to the photon signal are small. We failed to measure non-zero values of the linear polarization fraction η …

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Optical Rectification At Semiconductor Surfaces, Shun Lien Chuang, Stefan Schmitt-Rink, Benjamin I. Greene, Peter N. Saeta, Anthony F. J. Levi Jan 1992

Optical Rectification At Semiconductor Surfaces, Shun Lien Chuang, Stefan Schmitt-Rink, Benjamin I. Greene, Peter N. Saeta, Anthony F. J. Levi

All HMC Faculty Publications and Research

We show that far-infrared radiation can be generated in the depletion field near semiconductor surfaces via the inverse Franz-Keldysh effect or electric-field-induced optical rectification. This mechanism is conceptually different from those previously proposed and accounts for many recent experimental observations.

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Energetic Protons And Deuterons Emitted Following Μ⁻ Capture By ³He Nuclei, W. J. Cummings, G. E. Dodge, S. S. Hanna, B. H. King, S. E. Kuhn, Y. M. Shin, R. Helmer, R. B. Schubank, N. R. Stevenson, U. Wienands, Y. K. Lee, G. R. Mason, B. E. King, K. S. Chung, J. M. Lee, D. P. Rosenzweig Jan 1992

Energetic Protons And Deuterons Emitted Following Μ⁻ Capture By ³He Nuclei, W. J. Cummings, G. E. Dodge, S. S. Hanna, B. H. King, S. E. Kuhn, Y. M. Shin, R. Helmer, R. B. Schubank, N. R. Stevenson, U. Wienands, Y. K. Lee, G. R. Mason, B. E. King, K. S. Chung, J. M. Lee, D. P. Rosenzweig

Physics Faculty Publications

Spectra of energetic protons and deuterons emitted following negative muon capture from rest in 3He have been measured for the first time. Significant capture strength is observed at high energy transfers (mμ- Ev >60 MeV) for the two-body and three-body breakup channels, indicative of the importance of nucleon-nucleon correlations and meson exchange currents in the capture process. A simple plane wave impulse approximation calculation reproduces the proton spectrum reasonably well, but underpredicts the deuteron rate at the highest energies by a large factor.

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Science On The Great Plains: The History Of Physics And Astronomy At The University Of Nebraska-Lincoln, M. Eugene Rudd Jan 1992

Science On The Great Plains: The History Of Physics And Astronomy At The University Of Nebraska-Lincoln, M. Eugene Rudd

M. Eugene Rudd Publications

The year 1988 marked the 100th anniversary of the founding of the Department of Physics at the University of Nebraska. While the year passed without fanfare in the department, DuaneJaecks, one of the members of the faculty, suggested to the author that it would be a good time to write a history of what is now the Department of Physics and Astronomy. He not only provided the initial impetus for the project, but has also given it his continual help and encouragement. While the initial plan was to write only a brief, informal departmental history, the project, like Topsy, grew. …

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Homogeneous Nucleation Of Liquid From The Vapor Phase In An Expansion Cloud Chamber, John L. Schmitt Jan 1992

Homogeneous Nucleation Of Liquid From The Vapor Phase In An Expansion Cloud Chamber, John L. Schmitt

Physics Faculty Research & Creative Works

A Wilson expansion cloud chamber has been used to measure the homogeneous vapor-to-liquid nucleation of several materials over the past decade. These data, representing nucleation rate as a function of temperature and supersaturation ratio for toluene, nonane, and water measured in our center, have been re-examined and are presented both in graphical form and as a table of selected data points. The latter is included for ease of comparison with theory. Measurements of the binary homogeneous nucleation of ethanol-water (E-W) mixtures are also presented. The expansion chamber experimental technique and data reduction technique are discussed.

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Classical Calculation Of High-Energy Electron Capture In 5-Mev Proton-Hydrogen Collisions, D. R. Schultz, C. O. Reinhold, Ronald E. Olson Jan 1992

Classical Calculation Of High-Energy Electron Capture In 5-Mev Proton-Hydrogen Collisions, D. R. Schultz, C. O. Reinhold, Ronald E. Olson

Physics Faculty Research & Creative Works

The existence of the classical Thomas peak in the angular distribution of projectiles undergoing capture in collisions of 5-MeV protons with atomic hydrogen is explored using the three-body, three-dimensional classical-trajectory Monte Carlo technique. A method that selects only that portion of the initial phase space which yields capture at this energy was developed to make the calculation tractable due to the extremely small cross section. The spectrum obtained displays only a small shoulder near the angle predicted by Thomas on the basis of successive classical binary collisions and the total (integral) cross section is overestimated by a factor of 26 …

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Electromagnetic Wave Scattering From Magnetic Fluctuations In Tokamaks, L. L. Vahala, G. Vahala, N. Bretz Jan 1992

Electromagnetic Wave Scattering From Magnetic Fluctuations In Tokamaks, L. L. Vahala, G. Vahala, N. Bretz

Electrical & Computer Engineering Faculty Publications

Cross sections are calculated for electromagnetic wave scattering and mode transformation from magnetic and density fluctuations in a homogeneous plasma. For the special case of scattering perpendicular to the magnetic field, density fluctuations scatter ordinary to ordinary and extraordinary to extraordinary modes-but cannot transform these modes. On the other hand, magnetic fluctuations perpendicular to the field can transform modes but cannot scatter on a single branch. For incident frequencies on the order of the electron plasma frequency or gyrofrequency, the cross sections for scattering and transformation due to field and density fluctuations have a similar value. Estimates are given for …

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Covariant Phase Space Formulation Of Parametrized Field Theories, Charles G. Torre Jan 1992

Covariant Phase Space Formulation Of Parametrized Field Theories, Charles G. Torre

All Physics Faculty Publications

Parametrized field theories, which are generally covariant versions of ordinary field theories, are studied from the point of view of the covariant phase space: the space of solutions of the field equations equipped with a canonical (pre)symplectic structure. Motivated by issues arising in general relativity, we focus on phase space representations of the space‐time diffeomorphism group, construction of observables, and the relationship between the canonical and covariant phase spaces.

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Is General Relativity An "Already Parametrized" Theory?, Charles G. Torre Jan 1992

Is General Relativity An "Already Parametrized" Theory?, Charles G. Torre

All Physics Faculty Publications

Beginning with the work of Dirac and of Arnowitt, Deser, and Misner in the late 1950s and early 1960s, and then after subsequent development by Kuchař, the canonical dynamical structure of general relativity has often been viewed as that of a parametrized field theory in which the many-fingered spacetime variables are hidden among the geometrodynamical field variables. This paradigm of general relativity as an "already parametrized" theory forms the basis for one of the most satisfactory resolutions of the problems of time and observables in classical and quantum gravity. However, despite decades of effort, no identification of many-fingered spacetime variables …

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Solar Cycle Dependence Of Spacecraft Charging In Low Earth Orbit, T. B. Frooninckx, Jan Josef Sojka Jan 1992

Solar Cycle Dependence Of Spacecraft Charging In Low Earth Orbit, T. B. Frooninckx, Jan Josef Sojka

All Physics Faculty Publications

Recent experimental evidence has shown that Defense Meteorological Satellite Program (DMSP) polar orbiting spacecraft at 840 km can develop electric potentials as severe as −1430 V while at high magnetic latitudes. To explore this charging region, an analysis of DMSP F6, F7, F8, and F9 satellite precipitating particle and ambient plasma measurements taken during periods of high, medium, and low solar flux is performed. One hundred eighty-four charging events ranging from −46 to −1430 V are identified, and an extreme solar cycle dependence is found as charging is most frequent and severe during solar minimum. Satellite measurements and time-dependent ionospheric …

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Ionospheric Simulation Compared With Dynamics Explorer Observations For November 22, 1981, Jan Josef Sojka, M. D. Bowline, Robert W. Schunk, J. D. Craven, L. A. Frank, J. R. Sharber, J. D. Winningham, L. H. Brace Jan 1992

Ionospheric Simulation Compared With Dynamics Explorer Observations For November 22, 1981, Jan Josef Sojka, M. D. Bowline, Robert W. Schunk, J. D. Craven, L. A. Frank, J. R. Sharber, J. D. Winningham, L. H. Brace

All Physics Faculty Publications

Dynamics Explorer (DE) 2 electric field and particle data have been used to constrain the inputs of a time-dependent ionospheric model (TDIM) for a simulation of the ionosphere on November 22, 1981. The simulated densities have then been critically compared with the DE 2 electron density observations. This comparison uncovers a model-data disagreement in the morning sector trough, generally good agreement of the background density in the polar cap and evening sector trough, and a difficulty in modelling the observed polar F layer patches. From this comparison, the consequences of structure in the electric field and precipitation inputs can be …

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Analysis Of Experiments In Helium Microbeam Mixing, J B. Davis, R E. Benenson, David Peak Jan 1992

Analysis Of Experiments In Helium Microbeam Mixing, J B. Davis, R E. Benenson, David Peak

All Physics Faculty Publications

We have continued to investigate ion-beam mixing in bilay-er targets irradiated by 2-MeV He+ microbeams at room temperature. Although we have previously reported a linear dependence of interface width on dose for Cu/Al targets 1, more extensive results have not supported this conclusion, within statistical uncertainty, it appears that the interface width in Cu/Al (1) is proportional to the square root of dose, at constant dose rate, (2) is larger in Al than in Cu, for the same dose, (3) is proportional to the 1/4 power of dose rate, and (4) is absent at liquid nitrogen temperature. Calculations …

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Su(3) X Su(2) X U(1)Su(3): The Residual Symmetry Of Conformal Gravity, James Thomas Wheeler Jan 1992

Su(3) X Su(2) X U(1)Su(3): The Residual Symmetry Of Conformal Gravity, James Thomas Wheeler

All Physics Faculty Publications

SUe 4) x SU(2) is shown to characterize the possible choices of spacetime metric constructible from the gauge fields of the conformal group. When this symmetry is broken by the choice of metric, exactly the SU(3) x SU(2) x U(l) symmetry of the standard model remains. The conformal group consists of Lorentz transformations, translations, inverse translations and dilations. Treated in the standard way, conformal symmetry fails as a unifying gauge group: dilations make the mass spectrum continuous, and the inverse translational gauge field is auxiliary. The theory reduces back to the Poincare group.

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Fragmentation Of Percolation Clusters At The Percolation Threshold, M. F. Gyure, Boyd F. Edwards Jan 1992

Fragmentation Of Percolation Clusters At The Percolation Threshold, M. F. Gyure, Boyd F. Edwards

All Physics Faculty Publications

A scaling theory and simulation results are presented for fragmentation of percolation clusters by random bond dilution. At the percolation threshold, scaling forms describe the average number of fragmenting bonds and the distribution of cluster masses produced by fragmentation. A relationship between the scaling exponents and standard percolation exponents is verified in one dimension, on the Bethe lattice, and for Monte Carlo simulations on a square lattice. These results further describe the structure of percolation clusters and provide kernels relevant to rate equations for fragmentation.

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Density Effect In Cu K-Shell Ionization By 5.1-Gev Electrons, W. E. Meyerhof, D. G. Jensen, D. M. Kawall, S. E. Kuhn, D. W. Spooner, Z. E. Meziani, D.. N. Faust Jan 1992

Density Effect In Cu K-Shell Ionization By 5.1-Gev Electrons, W. E. Meyerhof, D. G. Jensen, D. M. Kawall, S. E. Kuhn, D. W. Spooner, Z. E. Meziani, D.. N. Faust

Physics Faculty Publications

We have made an absolute measurement of the Cu K-shell impact ionization cross section by 5.1-GeV electrons, which demonstrates directly a density effect predicted by Fermi in 1940. By determining the ratio of the K x-ray yield from a thin front and back layer of the target by a novel grazing emission method, we have verified the effect of transition radiation on the x-ray production, suggested by Sorensen and reported by Bak et al.

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Diffraction Of Light By A Focused Ultrasonic Wave, J. Huang, Joel Alan Nissen, Erik Bodegom Jan 1992

Diffraction Of Light By A Focused Ultrasonic Wave, J. Huang, Joel Alan Nissen, Erik Bodegom

Physics Faculty Publications and Presentations

The measurement of the acoustic pressure of a planar ultrasonic wave by light diffraction is well established. The ability to do similar measurements in the case of spherical waves has been doubted. However, we show that the range of validity can be extended to the focal region of a spherical concave piezoelectric transducer. Light is passed through the focal plane of a spherical concave transducer and is diffracted as a result of the variation in the index of refraction. The peak pressure can be calculated from the diffraction intensity by making the following simplification. We assume that in the focal …

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Hydration Behavior Of Laser Dye Aerosols Of Mixed Composition Having High Critical Supersaturations, Max B. Trueblood, Donald E. Hagen, Darryl J. Alofs Jan 1992

Hydration Behavior Of Laser Dye Aerosols Of Mixed Composition Having High Critical Supersaturations, Max B. Trueblood, Donald E. Hagen, Darryl J. Alofs

Mechanical and Aerospace Engineering Faculty Research & Creative Works

This Study Concerns Aerosol Particles of Mixed Composition. the Particles Contain a Water Insoluble Core (Polystyrene Latex), Surrounded by a Water Soluble Shell (Various Fluorescent Dyes). a Collison Nebulizer and an Electrostatic Aerosol Classifier Are Used to Prepare the Aerosol; its Critical Supersaturation Spectrum is Measured with a Diffusion Cloud Chamber. Experiments Were Done using Four Different Dyes (Disodium Fluorescein, Sulforhodamine 640, Sulforhodamine B and Rhodamine 560 Chloride) with Five Different Polystyrene Latex Sphere Sizes. the Results Indicate that a Kohler-Type Behavior is Obeyed. This Technique of Putting a Soluble Coating Onto an Insoluble Core is Found to Be a …

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Dynamic Mechanisms Of He Single Ionization By Fast Proton Impact, A. Gensmantel, J. Ullrich, R. Dörner, Ronald E. Olson, K. Ullmann, E. Forberich, S. Lencinas, H. Schmidt-Böcking Jan 1992

Dynamic Mechanisms Of He Single Ionization By Fast Proton Impact, A. Gensmantel, J. Ullrich, R. Dörner, Ronald E. Olson, K. Ullmann, E. Forberich, S. Lencinas, H. Schmidt-Böcking

Physics Faculty Research & Creative Works

Triple-differential ionization cross sections 3 pdcphipdprec, the momentum distributions of singly charged recoil ions transverse to the beam direction as a function of the projectile polar (p), and azimuthal (cphip) scattering angle were measured in order to elucidate the dynamics of 3-MeV H+ on He single ionization. For projectile polar deflections 0.2 p1 mrad and azimuthal scattering angles 0°cphip360°, the kinematic regimes where two-body interactions dominate the three-body momentum exchange of the single-ionization reaction were separated experimentally. © 1992 The American Physical Society.

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Temperature And Suction Effects On The Instability Of An Infinite Swept Attachment Line, D. G. Lasseigne, T. L. Jackson, F. Q. Hu Jan 1992

Temperature And Suction Effects On The Instability Of An Infinite Swept Attachment Line, D. G. Lasseigne, T. L. Jackson, F. Q. Hu

Mathematics & Statistics Faculty Publications

It is known that the incompressible, infinite swept attachment line flow is unstable to streamwise disturbances that originate in the boundary layer when the cross-flow exceeds a critical magnitude. Furthermore, a small degree of suction at the surface has a significant stabilizing influence while a small degree of blowing has a considerable destabilizing influence. This paper investigates the stabilizing and destabilizing effects of, respectively, cooling or heating the plate and the competing or enhancing effects of suction or blowing. A nonorthogonal flow with respect to the attachment line is also considered by adding a component of shear to the mean …

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Second-Order Parametrized-Post-Newtonian Lagrangian, Matthew J. Benacquista Jan 1992

Second-Order Parametrized-Post-Newtonian Lagrangian, Matthew J. Benacquista

Physics and Astronomy Faculty Publications and Presentations

A many-body Lagrangian to second post-Newtonian order using an extension of the parametrized-post-Newtonian (PPN) formalism is introduced and the properties of new parameters are explored. A parametrized gauge transformation is developed to permit comparison with theories of gravity in a variety of different coordinate systems. A procedure to impose Lorentz invariance on a general second-order post-Newtonian Lagrangian is developed. The Lagrangian is then constrained to possess Lorentz invariance and a "Lorentz-invariant" gauge is introduced. The constrained Lagrangian is found to be described by ten new second-order PPN parameters. When the Lagrangian is further constrained to describe theories of gravity for …

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Pressure And Temperature Effects On The Energy Of Formation For Silicon Clusters, Sung-Ho Suck Salk, Chen K. Lutrus, Donald E. Hagen, T. Oshiro, Steven M. Beck, Gary L. Loper Jan 1992

Pressure And Temperature Effects On The Energy Of Formation For Silicon Clusters, Sung-Ho Suck Salk, Chen K. Lutrus, Donald E. Hagen, T. Oshiro, Steven M. Beck, Gary L. Loper

Physics Faculty Research & Creative Works

At present most theoretical studies of atomic clusters are limited to their physical properties referred to 0 K. To the best of our knowledge, there exists no theoretical study of the simultaneous dependence of cluster formation and cluster-size distributions on both pressure and temperature. In the present work both pressure and temperature effects on the formation of silicon clusters are explored. A universal semiempirical formula is obtained to show a general trend in the variation of binding energy as a function of cluster size for both atomic and molecular clusters.

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Plasma As A High-Charge-State Projectile Stripping Medium, G. D. Alton, R. A. Sparrow, Ronald E. Olson Jan 1992

Plasma As A High-Charge-State Projectile Stripping Medium, G. D. Alton, R. A. Sparrow, Ronald E. Olson

Physics Faculty Research & Creative Works

The classical trajectory Monte Carlo model has been used to computationally study the charge-state distributions that result from interactions between a high-energy, multielectron projectile and neutral and fully ionized targets. These studies are designed to determine the properties of a plasma for producing highly stripped ions as a possible alternative to gas and foil strippers that are commonly used to enhance the charge states of energetic ion beams. The results of these studies clearly show that a low-atomic-number, highly ionized plasma can yield higher charge states than a neutral target of the same density. The effect is principally attributable to …

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Monte Carlo Study Of A Simple Model Bulk-Ice-Ih System: P-T Melting Behavior At Constant Volume, K. Han, Barbara N. Hale Jan 1992

Monte Carlo Study Of A Simple Model Bulk-Ice-Ih System: P-T Melting Behavior At Constant Volume, K. Han, Barbara N. Hale

Physics Faculty Research & Creative Works

An NVT Metropolis Monte Carlo computer simulation is used to examine the P-T behavior of a constant-density model periodic ice-Ih sample near melting. The ice unit cell with density 0.904 g/cm3 consists of 192 rigid water molecules interacting via the revised central-force potentials (RSL2) of Stillinger and Rahman [J. Chem. Phys. 68, 666 (1978)] with a cutoff. Intramolecular parameters are determined from a minimization of the total potential energy of the ice-Ih structure at 0 K. In the P-T plot, emergence of the liquid-solid coexistence region is signaled by a change in sign of dP/dT (when expansion occurs upon …

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Characterization Of As-Prepared And Annealed W/C Multilayer Thin Films, David D. Allred, Qi Wang, Jesus González-Hernández, B. S. Chao, D. A. Pawlik Jan 1992

Characterization Of As-Prepared And Annealed W/C Multilayer Thin Films, David D. Allred, Qi Wang, Jesus González-Hernández, B. S. Chao, D. A. Pawlik

Faculty Publications

Tungsten/carbon (W/C) multilayer thin films were prepared by dc magnetron sputtering. All samples consisted of 30 layer pairs with a nominal d-spacing varying from 2.5 to 14 nm, the W layer thickness was kept at 2 nm in all samples. The W/C multilayers were subjected to isochronal anneals in a quartz tube furnace at the temperature range from 500 to 950 °C under a flow of high purity Ar gas. X-ray diffraction, Raman scattering, and Auger depth profile were used to characterize the structure of the as-prepared and annealed multilayer films. Both the W and C layers appear to be …

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X-Ray Diode Using A Silicon Field Emission Photocathode, W. I. Karian, Larry V. Knight, David D. Allred, A. Reyes-Mena Jan 1992

X-Ray Diode Using A Silicon Field Emission Photocathode, W. I. Karian, Larry V. Knight, David D. Allred, A. Reyes-Mena

Faculty Publications

We have produced arrays of 10,000 sharp p-type silicon points using an etch plus oxidation method. The points were used as electron emitters. No high vacuum cesiation or high temperature cleaning was needed to observe the electron emission. These are seen to be photosensitive sources of electrons at 200 K and 300 K. They were also used to produce AlKα x-rays. This constitutes the first use of etched, point arrays for generating electrons for x-ray sources.

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