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Articles 33031 - 33060 of 36554

Full-Text Articles in Physical Sciences and Mathematics

Backward Peak In The Electron Spectrum From Collisions Of 70-Kev Protons With A Target From A Hydrogen-Atom Source, M. Eugene Rudd, M. W. Gealy, G. W. Kerby, Iii, Ying-Yuan Hsu Mar 1992

Backward Peak In The Electron Spectrum From Collisions Of 70-Kev Protons With A Target From A Hydrogen-Atom Source, M. Eugene Rudd, M. W. Gealy, G. W. Kerby, Iii, Ying-Yuan Hsu

M. Eugene Rudd Publications

A large, broad peak has been found in the electron energy spectrum from 30 to 100-keV H+ + H collisions. The peak, which is centered at 31 eV, appears only in the backward directions. It is suggested that while the peak is unlikely to come from collisions with atoms in the ground or metastable states, it could arise from collisions with atoms in highly excited states or from autoionizing states of the residual H2 in the target.

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Detection, Location, And Quantification Of Structural Damage By Neural-Netprocessed Moire Profilometry, Barry G. Grossman, Frank S. Gonzalez, Joel H. Blatt, Jeffery A. Hooker Mar 1992

Detection, Location, And Quantification Of Structural Damage By Neural-Netprocessed Moire Profilometry, Barry G. Grossman, Frank S. Gonzalez, Joel H. Blatt, Jeffery A. Hooker

Electrical Engineering and Computer Science Faculty Publications

The development of efficient high speed techniques to recognize, locate, and quantify damage is vitally important for successful automated inspection systems such as ones used for the inspection of undersea pipelines. Two critical problems must be solved to achieve these goals: the reduction of nonuseful information present in the video image and automatic recognition and quantification of extent and location of damage. Artificial neural network processed moire profilometry appears to be a promising technique to accomplish this. Real time video moire techniques have been developed which clearly distinguish damaged and undamaged areas on structures, thus reducing the amount of extraneous …

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Temporary Negative Ions And Vibrational Excitation In Ch3Cl And Cd3Cl, X. Shi, T.M. Stephen, Paul Burrow Mar 1992

Temporary Negative Ions And Vibrational Excitation In Ch3Cl And Cd3Cl, X. Shi, T.M. Stephen, Paul Burrow

Paul Burrow Publications

Electron energy loss spectroscopy is used to study the vibrational modes of CH3Cl and CD3Cl excited through the formation of a temporary negative ion state centered at 3.5 eV. Using symmetry and charge distribution arguments together with the experimentally determined excitation functions for several vibrational modes, we confirm that this resonance results from filling of the 8a1 (C–Cl) σ* molecular orbital. Evidence for a broad higher-lying resonance which we attribute to the unfilled 4e orbital is also presented.

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A Theoretical Investigation Of The Ground And Low‐Lying Excited States Of Butadiene Radical Cation, Robert J. Cave, Michael G. Perrott '90 Mar 1992

A Theoretical Investigation Of The Ground And Low‐Lying Excited States Of Butadiene Radical Cation, Robert J. Cave, Michael G. Perrott '90

All HMC Faculty Publications and Research

Results are presented from ab initio calculations on the ground and several low‐lying excited states of the butadiene radical cation. In particular, we have calculated geometries for the ground and several excited states at the multiconfiguration self‐consistent field level and characterized the planar stationary points. The vertical ionization potentials from the neutral molecule ground state and vertical excitation energies at the computed equilibrium geometry of the cation were also examined. A variety of methods were tested for the calculation of ionization potentials and excitation energies, including multiconfiguration self‐consistent field, multireference singles and doubles configuration interaction (with and without size‐consistency correction), …

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Intervalley Scattering In Gaas And Inp Probed By Pulsed Far‐Infrared Transmission Spectroscopy, Peter N. Saeta, John F. Federici, Benjamin I. Greene, Douglas R. Dykaar Mar 1992

Intervalley Scattering In Gaas And Inp Probed By Pulsed Far‐Infrared Transmission Spectroscopy, Peter N. Saeta, John F. Federici, Benjamin I. Greene, Douglas R. Dykaar

All HMC Faculty Publications and Research

The dynamics of photoexcited electrons in GaAs and InP were studied using the transmission of 200‐fs pulses of far‐infrared radiation in the spectral range 15–100 cm−1. Kinetic traces of the infrared transmission as a function of delay between optical excitation and infrared probe show a probe‐limited decrease in transmission followed by a more gradual (0.7–2 ps) drop to a steady value, consistent with the slow return of electrons from high‐mass satellite valleys. Infrared transmission spectra, analyzed in the context of a Drude model, reveal density‐dependent electron mobilities 3–4 times below equilibrium n‐doped values. Electron‐hole collisions likely account …

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Magnetic Relaxation And Irreversibility In A Superconducting Tl2Ba2Ca2Cu3O10±X Thin Film, V.K. Chan, Sy_Hwang Liou Mar 1992

Magnetic Relaxation And Irreversibility In A Superconducting Tl2Ba2Ca2Cu3O10±X Thin Film, V.K. Chan, Sy_Hwang Liou

Sy-Hwang Liou Publications

The magnetic relaxation in a Tl2Ba2Ca2Cu3O10±x superconducting thin film has been measured at a range of temperatures (5–70 K) and field strengths (500–5000 Oe). Measurements reveal that the relaxation obeys a logarithmic time dependence in the time interval 2000 s<t<12 000 s. The relaxation rate is both temperature and field dependent. The average pinning potential U* calculated from the relationship U*=kT/[(-1/Mi)dM/d lnt] is in the range 20–70 meV, which is similar to those of Y-Ba-Cu-O and (Bi,Pb)-Sr-Ca-Cu-O. The anomalous increase of U* at higher temperature is found to be closely related to …

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Numerical Analysis Of Plasma Transport In Tandem Volume Magnetic Multicusp Ion Sources, Todd R. Vitko Mar 1992

Numerical Analysis Of Plasma Transport In Tandem Volume Magnetic Multicusp Ion Sources, Todd R. Vitko

Theses and Dissertations

A one-dimensional fluid model of plasma transport in tandem volume magnetic multicusp ion sources is explored. The model, the positive ion source code pos, by Glasser and Smith, calculates plasma density, drift velocity, electron temperature, and ion temperature in an ion source. The usefulness of the model is limited: (1) The plasma density trend runs opposite to experimental results, and electron temperatures are an order of magnitude higher than experimentally observed. (2) simplification of the reaction chemistry leads to a plasma balance between ionization and outflow instead of the correct balance between ionization and recombination. (3) Wall losses are …

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Shock Tube Simulation By The Smooth Particle Hydrodynamic (Sph) Method, Luke A. Lorang Mar 1992

Shock Tube Simulation By The Smooth Particle Hydrodynamic (Sph) Method, Luke A. Lorang

Theses and Dissertations

A smooth particle hydrodynamic code (SPHC) is evaluated for performing shock wave simulations by application to 1-D shock tube problems. Results of a shock tube test case with a compression ratio of 10 are compared against a Riemann shock tube problem and theoretical predictions of shock tube behavior to validate the SPH code. A Lagrangian hydrodynamic code is validated in a similar fashion. The resolution capabilities of both codes are compared using 100, 200 and 500 particles for SPHC and 100, 400 and 800 cells for the Lagrangian code. The SPH code exhibits a sharp spike in density at the …

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Design And Construction Of A Channel Electron Multiplier Based Mossbauer Spectroscopy System, Daniel J. Robbins Mar 1992

Design And Construction Of A Channel Electron Multiplier Based Mossbauer Spectroscopy System, Daniel J. Robbins

Theses and Dissertations

A channel electron multiplier (cem) detector system was designed and built to provide a signal to a Mossbauer spectroscopy system in an effort to obtain a better signal-to-noise ratio than achievable with a proportional counter system. Three cems are contained in a vacuum chamber built using standard components. Gamma, rays of 14.4-keV energy from a 57Co source enter from outside the chamber through a window and are absorbed by an 57Fe target near the cems. The target emits internal conversion electrons which are collected by the cems and a Mossbauer spectrometer collects the signal. The system produces a …

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W Boson Condensation In P-P Collisions?, Alec Schramm, Stefan Schramm, Berndt Muller Feb 1992

W Boson Condensation In P-P Collisions?, Alec Schramm, Stefan Schramm, Berndt Muller

Alec J Schramm

We address the question of whether W+/- boson condensation can occur in high-energy collisions.

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Three-Dimensional Structure Of The Ordered Phases Of Hg On Cu(001), Wei Li, Jingsu Lin, M. Karimi, Peter A. Dowben, G. Vidali Feb 1992

Three-Dimensional Structure Of The Ordered Phases Of Hg On Cu(001), Wei Li, Jingsu Lin, M. Karimi, Peter A. Dowben, G. Vidali

Peter Dowben Publications

The structures of ordered phases following adsorption of mercury on Cu(001) have been identified using helium-beam scattering and low-energy electron diffraction. We found that three of the four observed ordered submonolayer phases are high-order commensurate phases. The three-dimensional structure of these phases brought about by a periodic variation of the height of the Hg atoms above the Cu(001) plane has been measured. Furthermore, from a combined analysis of helium-beam scattering and angle-resolved photoemission data for a low-density Hg ordered overlayer, we deduce and quantify the departure from the atomic electron distribution of Hg due to adsorption. A model to analyze …

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Coverage Dependence Of K Adsorption On Si(100)—2× 1 By Core-Level Photoemission, D. Mark Riffe, G. K. Wertheim, P. H. Citrin, J. E. Rowe Feb 1992

Coverage Dependence Of K Adsorption On Si(100)—2× 1 By Core-Level Photoemission, D. Mark Riffe, G. K. Wertheim, P. H. Citrin, J. E. Rowe

All Physics Faculty Publications

Using core-level photoemission, a coverage-dependent transition in the adsorption of K on Si(100)2×1 is observed. Below ∼0.25 monolayers, a single adsorption is occupied, the asymmetry of the Si-dimer reconstruction is enhanced, and no more than ∼0.05e is transferred from K to Si. Above this coverage, multiple sites are occupied, the dimer configuration becomes more symmetric, and the K overlayer becomes increasingly metallic. These findings resolve a number of conflicting studies of this system.

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Mott Electron Polarimetry, Timothy J. Gay, F. B. Dunning Feb 1992

Mott Electron Polarimetry, Timothy J. Gay, F. B. Dunning

Timothy J. Gay Publications

Electron polarimeters based on Mott scattering are extensively used in atomic and molecular, solid state, nuclear, and high-energy physics. This use stems from the increasing realization that much additional information concerning many physical processes can be obtained through spin-dependent measurements. In this review we discuss the basic physics and application of Mott polarimetry. A number of different Mott polarimeter designs are described that illustrate the wide range of operating energies (10 eV-1 MeV) and geometries that can be used in such instruments. The calibration of Mott polarimeters is discussed together with the potential sources of systematic error that can arise …

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Tem Observations Of The Mechanism Of Delamination Of Chromium Films From Silicon Substrates, D. Goyal, Alexander H. King Feb 1992

Tem Observations Of The Mechanism Of Delamination Of Chromium Films From Silicon Substrates, D. Goyal, Alexander H. King

Alexander H. King

We have observed the complete delamination of polycrystalline chromium films from single crystal silicon substrates during deposition due to the formation of high internal stresses. These intrinsic stresses can give rise to interfacial defects which assist in the separation of the film from the substrate. Stresses in the film are balanced by stresses in the substrate, which cause mechanical failure in the substrate near the interface. Extensive arrays of dislocations and cracking of the substrate have been observed. We find that the delamination of the films from the substrate is initiated by the formation of damage in the substrate, rather …

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Electron-Paramagnetic-Resonance Study Of Gaas Grown By Low-Temperature Molecular-Beam Epitaxy, H. J. Vonbardeleben, M. O. Manasreh, David C. Look, K. R. Evans, C. E. Stutz Feb 1992

Electron-Paramagnetic-Resonance Study Of Gaas Grown By Low-Temperature Molecular-Beam Epitaxy, H. J. Vonbardeleben, M. O. Manasreh, David C. Look, K. R. Evans, C. E. Stutz

Physics Faculty Publications

Electron-paramagnetic-resonance results demonstrate an arsenic-antisite related deep donor defect to be the dominant native defect in GaAs layers grown by low-temperature molecular-beam epitaxy (LTMBE). This defect is different from the EL2-related native arsenic-antisite defect. The thermal-equilibrium concentration of 3×1018 cm−3 ionized AsGa defects directly shows the additional presence of unidentified acceptor defects in the same concentration range. The defect distribution in GaAs grown by LTMBE is unstable under thermal annealing at T≳500 °C.

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Angular-Differential Cross Sections For H(2p) Formation In Intermediate-Energy Proton-Helium Collisions, Denver G. Seely, S. W. Bross, A. D. Gaus, John Wm Edwards, David R. Schultz, Timothy Gay, John T. Park, Jerry Peacher Feb 1992

Angular-Differential Cross Sections For H(2p) Formation In Intermediate-Energy Proton-Helium Collisions, Denver G. Seely, S. W. Bross, A. D. Gaus, John Wm Edwards, David R. Schultz, Timothy Gay, John T. Park, Jerry Peacher

Physics Faculty Research & Creative Works

Angular-differential cross sections for charge transfer with simultaneous emission of a photon in collisions of protons with helium atoms have been measured. The incident proton energies were 25, 50, and 100 keV and the center-of-mass scattering angles were between 0 and 2.0 mrad. In the experiment, hydrogen atoms that scattered through an angle θ were detected in coincidence with photons emitted perpendicular to the scattering plane with a wavelength between 1140 and 1400 Å. Differential cross sections for capture into the 2p state of the hydrogen atom were determined from the variation in the coincidence signal with θ. The experimental …

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Determining The Chemical Composition Of Cloud Condensation Nuclei, Allen L. Williams, Jane E. Rothert, Kent E. Mcclure, Darryl J. Alofs, Donald E. Hagen, Daniel R. White, A. R. Hopkins, Max B. Trueblood Feb 1992

Determining The Chemical Composition Of Cloud Condensation Nuclei, Allen L. Williams, Jane E. Rothert, Kent E. Mcclure, Darryl J. Alofs, Donald E. Hagen, Daniel R. White, A. R. Hopkins, Max B. Trueblood

Mechanical and Aerospace Engineering Faculty Research & Creative Works

This second progress report describes the status of the project one and one-half years after the start. The goal of the project is to develop the instrumentation to collect cloud condensation nuclei (CCN) in sufficient amounts to determine their chemical composition, and to survey the CCN composition in different climates through a series of field measurements. Our approach to CCN collection is to first form droplets on the nuclei under simulated cloud humidity conditions, which is the only known method of identifying CCN from the background aerosol. Under cloud chamber conditions, the droplets formed become larger than the surrounding aerosol, …

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Angular-Differential Cross Sections For H(2P) Formation In Intermediate-Energy Proton-Helium Collisions, D. G. Seely, S. W. Bross, A. D. Gaus, J. W. Edwards, D. R. Schultz, Timothy J. Gay, J. T. Park, J. L. Peacher Feb 1992

Angular-Differential Cross Sections For H(2P) Formation In Intermediate-Energy Proton-Helium Collisions, D. G. Seely, S. W. Bross, A. D. Gaus, J. W. Edwards, D. R. Schultz, Timothy J. Gay, J. T. Park, J. L. Peacher

Timothy J. Gay Publications

Angular-differential cross sections for charge transfer with simultaneous emission of a photon in collisions of protons with helium atoms have been measured. The incident proton energies were 25, 50, and 100 keV and the center-of-mass scattering angles were between 0 and 2.0 mrad. In the experiment, hydrogen atoms that scattered through an angle θ were detected in coincidence with photons emitted perpendicular to the scattering plane with a wavelength between 1140 and 1400 Å. Differential cross sections for capture into the 2p state of the hydrogen atom were determined from the variation in the coincidence signal with θ. The …

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Hamiltonian Bifurcation Theory Of Closed Orbits In The Diamagnetic Kepler Problem, J. M. Mao, John B. Delos Feb 1992

Hamiltonian Bifurcation Theory Of Closed Orbits In The Diamagnetic Kepler Problem, J. M. Mao, John B. Delos

Arts & Sciences Articles

Classically chaotic systems possess a proliferation of periodic orbits. This phenomenon was observed in a quantum system through measurements of the absorption spectrum of a hydrogen atom in a magnetic field. This paper gives a theoretical interpretation of the bifurcations of periodic or closed orbits of electrons in atoms in magnetic fields. We ask how new periodic orbits can be created out of existing ones or ‘‘out of nowhere’’ as the energy changes. Hamiltonian bifurcation theory provides the answer: it asserts the existence of just five typical types of bifurcation in conservative systems with two degrees of freedom. We show …

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Light Scattering In The Isotropic Phase Of Highly Chiral Liquid Crystals, J. E. Wyse, Peter J. Collings Feb 1992

Light Scattering In The Isotropic Phase Of Highly Chiral Liquid Crystals, J. E. Wyse, Peter J. Collings

Physics & Astronomy Faculty Works

Light-scattering measurements using circularly polarized light in a backscattering geometry are employed to measure the amplitude of fluctuations in two of the five structural modes present in the isotropic phase of chiral liquid crystals. From these measurements, the second-order transition temperatures for all five modes are then calculated. In order to investigate the effect of chirality on the fluctuations, the experiments are performed in various mixtures of the chiral liquid crystal 4’’-(2-methylbutylphenyl)-4’-(2-methylbutyl)-4-biphenylcarboxylate (CE2) and the nonchiral liquid crystal 4-n-pentylbenzenethio-4’-n-heptyloxybenzoate(7¯S5). The results show that fluctuations in the five modes are independent in low-chirality mixtures, and, as predicted by theory, the second-order …

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Evidence For Atomic Processes In Molecular Valence Double Ionization, U. Becker, Oliver Hemmers, B. Langer, A. Menzel, R. Wehlitz, W. B. Peatman Feb 1992

Evidence For Atomic Processes In Molecular Valence Double Ionization, U. Becker, Oliver Hemmers, B. Langer, A. Menzel, R. Wehlitz, W. B. Peatman

Environmental Studies Faculty Publications

Complete molecular valence-electron spectra were measured for CO. Unexpectedly, discrete lines at low kinetic energies were found, superimposed on a continuous energy spectrum representing direct double-ionization processes. The appearance of these lines is discussed in the context of the formation of the C++O+ ion pair near its associated threshold at 38.4 eV. It is ascribed to valence-excited repulsive (CO+)* states, which dissociate to a large part rapidly into atomic fragments before electronic relaxation takes place. From our spectra, partial cross sections for the different processes leading to dissociative valence double ionization are derived.

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Finite Thermal Diffusivity At Onset Of Convection In Autocatalytic Systems: Continuous Fluid Density, J. W. Wilder, Boyd F. Edwards, D. A. Vasquez Feb 1992

Finite Thermal Diffusivity At Onset Of Convection In Autocatalytic Systems: Continuous Fluid Density, J. W. Wilder, Boyd F. Edwards, D. A. Vasquez

All Physics Faculty Publications

The linear stability of exothermic autocatalytic reaction fronts is considered using the viscous thermohydrodynamic equations for a fluid with finite thermal diffusivity. For upward front propagation and a thin front, the vertical thermal gradient near the front is reminiscent of the Rayleigh-Bénard problem of a fluid layer heated from below. The problem is also similar to flame propagation, except that here the front propagation speed is limited by catalyst diffusion rather than by activation kinetics. For small density changes in a laterally unbounded system, the curvature dependence of the front propagation speed stabilizes perturbations with short wavelengths λ<λc, …

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Mössbauer And Neutron Diffraction Studies Of Y₂(Fe₁₋ₓmnₓ)₁₄B, Oran Allan Pringle, Gaya Kanishka Marasinghe, Gary J. Long, William Joseph James, William B. Yelon, Decai Xie, Fernande Grandjean Feb 1992

Mössbauer And Neutron Diffraction Studies Of Y₂(Fe₁₋ₓmnₓ)₁₄B, Oran Allan Pringle, Gaya Kanishka Marasinghe, Gary J. Long, William Joseph James, William B. Yelon, Decai Xie, Fernande Grandjean

Physics Faculty Research & Creative Works

We have used Mössbauer spectroscopy and neutron diffraction to study a series of Y2(Fe1-xMnx)1 4B samples in the composition range from x=0.0 to 0.4. Y 2(Fe0.6Mn0.4)14B is paramagnetic at both room temperature and 85 K. The iron quadrupole splitting in this paramagnetic compound allows us to place an upper limit on the quadrupole shift in the magnetic Y2(Fe1-xMnx) 14B alloys. Refinement of Y2(Fe 1-xMnx)14B neutron diffraction data have been used to …

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The Effect Of Continuous Stirring On Off-Critical And Critical Samples Of A Phase Separating Binary Liquid Mixture, Nalini Easwar Jan 1992

The Effect Of Continuous Stirring On Off-Critical And Critical Samples Of A Phase Separating Binary Liquid Mixture, Nalini Easwar

Physics: Faculty Publications

The effect of shear on phase separation in a continuously stirred mixture of isobutyric acid and water has been studied. The data for the onset of phase separation in the stirred samples that are as far away as 500 mK from the critical point compare favorably with the theory of Onuki and Takasue and with similar measurements on very off-critical mixtures of 2-6 lutidine plus water reported by Min et al. However, as the composition gets closer to the critical composition significant differences arise. The main feature is that the measured suppression in temperature peaks at an off-critical composition …

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The Effect Of Diamagnetic Dilution On The Spin-Phonon Interaction And Scattering Cross Section In Fe1-Xznxf2, Christian Binek Jan 1992

The Effect Of Diamagnetic Dilution On The Spin-Phonon Interaction And Scattering Cross Section In Fe1-Xznxf2, Christian Binek

Christian Binek Publications

The temperature dependences of the first moments of phonon Raman scattering lines are studied for Fe1-xZnxF2. The diamagnetic dilution diminishes the spin-phonon coupling strength of phonons with both A1g and Eg symmetry in proportion to the decrease in the ordering temperature TN. Moreover, the Eg mode shows an asymmetrical lineshape for Zn concentrations x>0.3. It is explained by an unresolved superposition of two modes, one of which is ascribed to perturbed ZnF2 with broken translational symmetry.

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Stationary Solutions For An Electron In An Intense Laser Field. Ii. Multimode Case, D. S. Guo, Gordon W. F. Drake Jan 1992

Stationary Solutions For An Electron In An Intense Laser Field. Ii. Multimode Case, D. S. Guo, Gordon W. F. Drake

Physics Publications

The Schrodinger equation for an electron and a multimode photon field with interactions is solved in the large-phonon-number limit by using an 'integration' method. A graphical technique different from Feynman's is developed to represent the terms in the solution. By this graphical technique, all interactions between the electron and the multimode photon field are evaluated to any arbitrary order according to the number of transferred photons. The graphical technique allows one easily to write down the wavefunctions for an electron interacting with a strong photon field which contains an arbitrary number of photon modes. The two-mode case is discussed in …

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Stationary Solutions For An Electron In An Intense Laser Field. I. Single-Mode Case, D. S. Guo, Gordon W. F. Drake Jan 1992

Stationary Solutions For An Electron In An Intense Laser Field. I. Single-Mode Case, D. S. Guo, Gordon W. F. Drake

Physics Publications

The Schrodinger equation for an electron and a single-mode photon field with interactions is solved by a direct method. A unique feature of these solutions is the inclusion of retardation effects in the photon field. Some interesting physical questions arising from the solutions are discussed. The Keldysh-Faisal-Reiss formula for the transition rate of multiphoton ionization modified by the inclusion of retardation effects is simplified by averaging the degenerate initial states. The result shows that the retardation effects can be calculated in terms of the radial part of the momentum wavefunction of the initial state. The physical significance of the inclusion …

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The Doubly-Excited State 2p 2 3p For 1 ≤ Z ≤ 4: Coulomb Holes Derived From Explicitly Correlated Wavefunctions, K. E. Banyard, D. R. T. Keeble, Gordon W. F. Drake Jan 1992

The Doubly-Excited State 2p 2 3p For 1 ≤ Z ≤ 4: Coulomb Holes Derived From Explicitly Correlated Wavefunctions, K. E. Banyard, D. R. T. Keeble, Gordon W. F. Drake

Physics Publications

Doubly-excited states (DES) of simple atoms involve, by comparison with the ground state, relatively slow moving electrons which should therefore be more responsive to electron correlation. Hence, for the 2p 23P state, correlation effects have been analyzed in detail in terms of Coulomb holes, partial Coulomb holes and (r n 12) when 1 ≤ Z ≤ 4. Comparisons are made with the 1s 2 1S ground state and with the singly-excited state 1s2p, 3P. As for the lower states, each DES was described by an accurate explicitly correlated wavefunction. For each Z, a similarity of characteristics, but not of scale, …

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Erratum: Asymptotic Expansion For -Function Matrix Elements Of Helium (Phys. Rev. A (1992) 45,9 (6933-6934)), Gordon W. F. Drake Jan 1992

Erratum: Asymptotic Expansion For -Function Matrix Elements Of Helium (Phys. Rev. A (1992) 45,9 (6933-6934)), Gordon W. F. Drake

Physics Publications

No abstract provided.

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Multiphoton Ionization In Circularly Polarized Standing Waves, D. S. Guo, Gordon W. F. Drake Jan 1992

Multiphoton Ionization In Circularly Polarized Standing Waves, D. S. Guo, Gordon W. F. Drake

Physics Publications

We derive the wave functions for an electron moving in a quantized circularly polarized standing-wave radiation field. By applying these solutions as the final states, we derive multiphoton ionization transition-rate formulas according to Keldysh-Faisal-Reiss (KFR) theory. Numerical calculations and theoretical analysis show that in the case of two light beams with the same angular momentum, KFR theory does not predict the peak splittings in the photoelectron angular distributions that were observed in an experiment by Bucksbaum, Schumacher, and Bashkansky (BSB) [Phys. Rev. Lett. 61, 1162 (1988)]. A transition-rate formula from a scattering theory developed for the case of single-mode multiphoton …

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