Open Access. Powered by Scholars. Published by Universities.®
Physical Sciences and Mathematics Commons™
Open Access. Powered by Scholars. Published by Universities.®
- Discipline
-
- Physics (1742)
- Chemistry (77)
- Computer Sciences (44)
- Numerical Analysis and Scientific Computing (44)
- Engineering (19)
-
- Materials Science and Engineering (10)
- Astrophysics and Astronomy (6)
- Metallurgy (5)
- Aerospace Engineering (4)
- Mechanical Engineering (4)
- Social and Behavioral Sciences (3)
- Earth Sciences (2)
- Geology (2)
- Psychology (2)
- Biochemical and Biomolecular Engineering (1)
- Chemical Engineering (1)
- Civil and Environmental Engineering (1)
- Electrical and Computer Engineering (1)
- Library and Information Science (1)
- Nuclear Engineering (1)
- Keyword
-
- Ionization (58)
- Electrons (42)
- Quantum Theory (42)
- Helium (36)
- Atoms (34)
-
- Hydrogen (34)
- Electrodynamics (32)
- Gravitational waves (31)
- Gravity waves (29)
- Molecules (29)
- Gravitational effects (28)
- Photons (28)
- Impact ionization (25)
- Atomic physics (22)
- Gravitation (21)
- Impact Ionization (19)
- Quantum theory (19)
- Electron Energy Levels (18)
- Atomic Physics (17)
- Photoionization (17)
- Stars (17)
- Ions (16)
- Mathematical models (16)
- Projectiles (16)
- Electron impact-ionization (15)
- Hamiltonians (15)
- Polarization (15)
- Quantum Electrodynamics (15)
- Electron energy levels (14)
- Gravitational-wave signals (14)
- Publication Year
Articles 1561 - 1590 of 1762
Full-Text Articles in Physical Sciences and Mathematics
Crystal Perfection Of Hgi2 Studied By Neutron And Gamma-Ray Diffraction, W. (William) B. Yelon, R. W. Alkire, M. M. Schieber, L. Van Den Berg, S. E. Rasmussen, H. Christensen, J. R. Schneider
Crystal Perfection Of Hgi2 Studied By Neutron And Gamma-Ray Diffraction, W. (William) B. Yelon, R. W. Alkire, M. M. Schieber, L. Van Den Berg, S. E. Rasmussen, H. Christensen, J. R. Schneider
Physics Faculty Research & Creative Works
The crystalline perfection of wire sawn pieces of vapor grown single crystals of mercuric iodide was compared with the perfection of (00l) cleaved sections of the same crystal from which nuclear radiation detectors have been fabricated. The crystalline perfection was studied using neutron and gamma-ray diffraction rocking curves. Most of the gamma-ray data were obtained using a high intensity source of 153Sm gamma rays with a wavelength of λ = 0.12 Å. Some of the data were obtained using highly penetrating 198Au gamma rays with a shorter wavelength of λ = 0.03 Å. The neutrons had a wavelength of λ …
Orientation Of Atoms Excited By Charged Particles At High Impact Energies, Don H. Madison, Kieth H. Winters
Orientation Of Atoms Excited By Charged Particles At High Impact Energies, Don H. Madison, Kieth H. Winters
Physics Faculty Research & Creative Works
A perturbation-expansion approach is used to examine the sign of the orientation vector as a function of scattering angle and projectile charge. It is shown that for small angles, the sign of the orientation vector is different for oppositely charged projectiles consistent with the prediction of the classical grazing model. At large angles, on the other hand, the orientation vector for oppositely charged projectiles is shown to have the same sign.
The Water Monomer On The Prism Face Of Ice And Above A Four Layer Ice Basal Face Ledge: An Effective Pair Potential Model, Barbara N. Hale, Jerry Kiefer, Carolyn A. Ward
The Water Monomer On The Prism Face Of Ice And Above A Four Layer Ice Basal Face Ledge: An Effective Pair Potential Model, Barbara N. Hale, Jerry Kiefer, Carolyn A. Ward
Physics Faculty Research & Creative Works
A previous study of the water monomer on the basal faces of ice is extended to consider the interaction of the water molecule with a rigid prism face of ice and with an ice basal face ledge. The effective central force H2O-H2O potentials of Stillinger and Rahman are used to generate maximal binding energy surfaces for the H2O adsorbed on the sample substrates. The results indicate that the prism face of ice binds the water molecule more strongly than the basal faces, and the step on the basal face serves to expose high binding …
Electron Capture At Very Small Scattering Angles From Atomic Hydrogen By 25-125-Kev Protons, Paul J. Martin, D. M. Blankenship, Thomas J. Kvale, E. Redd, Jerry Peacher, John T. Park
Electron Capture At Very Small Scattering Angles From Atomic Hydrogen By 25-125-Kev Protons, Paul J. Martin, D. M. Blankenship, Thomas J. Kvale, E. Redd, Jerry Peacher, John T. Park
Physics Faculty Research & Creative Works
Differential cross sections for electron capture in collisions between protons and hydrogen atoms have been experimentally determined for incident proton energies of 25, 60, and 125 keV in the center-of-mass scattering-angle range of 0-3 mrad. The experimental results compare more favorably with the results of both a multistate and a two-state calculation than with the results of a continuum distorted-wave-approximation calculation. There is no evidence of a Jackson-Schiff-type minimum.
Differential Cross Sections For Electron Capture From Helium By 25- To 100-Kev Incident Protons, Paul J. Martin, Kenneth E. Arnett, D. M. Blankenship, Thomas J. Kvale, Jerry Peacher, E. Redd, V. C. Sutcliffe, John T. Park, Chiidong Lin, Jim H. Mcguire
Differential Cross Sections For Electron Capture From Helium By 25- To 100-Kev Incident Protons, Paul J. Martin, Kenneth E. Arnett, D. M. Blankenship, Thomas J. Kvale, Jerry Peacher, E. Redd, V. C. Sutcliffe, John T. Park, Chiidong Lin, Jim H. Mcguire
Physics Faculty Research & Creative Works
Experimentally and theoretically determined differential cross sections are reported for electron capture in collisions of protons with helium atoms for incident proton energies of 25, 30, 50, and 100 keV and for center-of-mass scattering angles of 0.0 to 2.0 mrad. The magnitudes of the experimentally determined differential cross sections decrease from 10-10 to 10-12 cm2/sr within the 0.0-0.8-mrad range of the center-of-mass scattering angle. At approximately 0.8 mrad a distinct change in the slope of the differential cross section is observed. The experimental results which are for capture into all bound states of hydrogen are compared …
Angular Differential And Total Cross Sections For The Excitation Of Atomic Hydrogen To Its N=2 State By Helium Ions, Judith E. Aldag, Jerry Peacher, Paul J. Martin, V. C. Sutcliffe, Jacob M. George, E. Redd, Thomas J. Kvale, D. M. Blankenship, John T. Park
Angular Differential And Total Cross Sections For The Excitation Of Atomic Hydrogen To Its N=2 State By Helium Ions, Judith E. Aldag, Jerry Peacher, Paul J. Martin, V. C. Sutcliffe, Jacob M. George, E. Redd, Thomas J. Kvale, D. M. Blankenship, John T. Park
Physics Faculty Research & Creative Works
Differential cross sections for 15-100 keV He+ excitation of atomic hydrogen to its n=2 level have been determined for c.m. angles from 0 to 8 mrad. The differential cross sections are obtained from an analysis of the angular distribution of the scattered ions which have lost an energy corresponding to the excitation of the target to its n=2 level. The shape of the differential cross section changes rapidly with increasing incident energy. At 15 keV, the differential cross section falls off by a factor of 5 in 6 mrad. At 100 keV, the differential cross section decreases by nearly …
Effect Of Polarization And Absorption On Differential Cross Sections And Angular Correlation Parameters For Electron Excitation Of Helium, M. E. Stewart, Don H. Madison
Effect Of Polarization And Absorption On Differential Cross Sections And Angular Correlation Parameters For Electron Excitation Of Helium, M. E. Stewart, Don H. Madison
Physics Faculty Research & Creative Works
The effects of local polarization and absorption potentials on differential cross sections and angular correlation parameters are studied within the distorted-wave approximation for electron excitation of the 2 1P state of helium. For examining the effect of local polarization, we have compared a recent numerical self-consistent adiabatic polarization potential for helium with the commonly used hydrogenic adiabatic polarization potential. Different radial regions for the polarization potential were studied to determine their contribution to the overall effect of polarization. Calculations are also presented which show the effects of different strengths for a local absorption potential.
Effective Swarm Parameters And Transport Coefficients In Co2 Laser Mixtures, R. A. Sierra, H. L. Brooks, A. J. Sommerer, S. R. Foltyn, Kaare J. Nygaard
Effective Swarm Parameters And Transport Coefficients In Co2 Laser Mixtures, R. A. Sierra, H. L. Brooks, A. J. Sommerer, S. R. Foltyn, Kaare J. Nygaard
Physics Faculty Research & Creative Works
A pulsed electron swarm technique has been used to obtain effective attachment and ionization cross-sections as well as electron drift velocities in mixtures of CO2 laser interest. In binary CO2:N 2 mixtures, below a reduced electric field of E/N=60*10 -17 V cm2, attachment was the principal ion production process. (N is the total gas number density.) The reduced attachment coefficients measured were small and in excellent agreement with numerical predictions. In ternary mixtures of He:CO2:N2, positive ion formation described by Townsend's first ionisation coefficient played a more important role over the same range of E/N. …
N,L Distributions In Aq++H Electron-Capture Collisions, R. (Ronald) E. Olson
N,L Distributions In Aq++H Electron-Capture Collisions, R. (Ronald) E. Olson
Physics Faculty Research & Creative Works
The classical-trajectory Monte Carlo method has been used to determine product-state distributions in Aq++HA(q-1)+(nl)+H+ electron-capture collisions at energies 50 and 100 keV/amu for fully stripped ions in charge states q=1to 20. In the energy region studied, the electron-capture products are found to populate predominately principal quantum numbers around nmq34. Such behavior implies the captured electron tries to preserve both its original orbital energy and dimensions after the electron-capture collision. The orbital-angular-momentum quantum numbers l are more highly peaked than statistical to large l values for nnm. © 1981 The American Physical Society.
Modern Spectroscopy With A Spectrometer By The Optogalvanic Effect, Kenneth Arnett, Richard A. Anderson, Ralph William Alexander
Modern Spectroscopy With A Spectrometer By The Optogalvanic Effect, Kenneth Arnett, Richard A. Anderson, Ralph William Alexander
Physics Faculty Research & Creative Works
An Experiment Involving the Optogalvanic Effect Suitable for the Advanced Physics Laboratory is Described. This Experiment Complements the Usual Basic Experiment in Atomic Spectroscopy Where Spectra Are Recorded on Photographic Film with a Spectrograph or with a Monochromator and Photomultiplier. the Optogalvanic Effect Used the Atoms Being Studied as the Detector and a Tunable Dye Laser as the Source. Linewidths Observed Are Those of the Dye Laser that Are Considerably Smaller Than Those Obtained with the Usual Laboratory Monochromator. the student is Introduced to the Techniques of Spectroscopy with Pulsed Dye Lasers and to a Spectrum for Which LS Coupling …
Excitation Transfer In Ion Rydberg-Atom Collisions, R. (Ronald) E. Olson
Excitation Transfer In Ion Rydberg-Atom Collisions, R. (Ronald) E. Olson
Physics Faculty Research & Creative Works
Recently, electron-loss cross sections were presented by Kim and Meyer [Phys. Rev. Lett. 44, 1047 (1980)] for 40 keV/amu N3+ + H**(n) collisions which scaled as n3.12, where n is the principal quantum number of the excited H0. Such results are in contrast to an n2 scaling predicted by classical and first-Born theoretical methods. Our calculations indicate that a major component of the experimentally observed ion signal was due to Stark ionization by deflector grids of highly excited H0 produced in excitation-transfer collisions. Inclusion of the excitation process in a theoretical interpretation reveals qualitative agreement between theory and experiment and …
Excitation Transfer Collisions And Electron Seeding Processes In A Resonantly Excited Sodium Vapor, D. J. Krebs, Laird D. Schearer
Excitation Transfer Collisions And Electron Seeding Processes In A Resonantly Excited Sodium Vapor, D. J. Krebs, Laird D. Schearer
Physics Faculty Research & Creative Works
A dense sodium vapor in a high-pressure buffer of argon has been simultaneously excited by short (4 ns) laser pulses from two lasers: the first tuned to one of the D line transitions at 589 nm and the second tuned to the photoionization threshold of the 3p states near 406 nm. The temporal evolution of the system was studied with and without the photoionizing laser pulses. At early times (∼100 ns) excited state populations are determined by energy transfer collisions between two laser-excited 3p atoms while the ion/electron density is controlled by super elastic heating of "seed" electrons followed by …
High Flux Beam Source Of Thermal Rare-Gas Metastable Atoms, D. W. Fahey, William F. Parks, Laird D. Schearer
High Flux Beam Source Of Thermal Rare-Gas Metastable Atoms, D. W. Fahey, William F. Parks, Laird D. Schearer
Physics Faculty Research & Creative Works
A high-flux beam source has been constructed for the production of helium, neon and argon metastable atoms. The source is a DC electric discharge maintained in an expanding gas. A metastable flux of 3.5*1014, and 7.2*1013 atoms s-1 sr-1 has been achieved with most probable energies of 66, 72 and 74 meV for the helium, neon and argon sources, respectively. Time-of-flight measurements showed the widths of the respective velocity distributions to be 45%, 27% and 27%.
Thermal Decomposition Kinetics Of Asf5-Doped Polyacetylene In Vacuum, T. Inoue, J. E. Osterholm, H. Yasuda, L. L. Levenson
Thermal Decomposition Kinetics Of Asf5-Doped Polyacetylene In Vacuum, T. Inoue, J. E. Osterholm, H. Yasuda, L. L. Levenson
Physics Faculty Research & Creative Works
Electrical conductivity measurements, mass spectra of desorbing species, and ESCA surface analysis are reported for AsF5-doped polyacetylene heated between 50 and 130°C in vacuum. All measurements indicate first-order decomposition kinetics with activation energies between 13 and 20 kcal mole-1. Decomposition leads to the desorption of AsF3 and F2. Metallic arsenic remains in the polyacetylene as a decomposition by-product.
Studies Of H₂O On Ss-Agi Surfaces: An Effective Pair Potential Model, Barbara N. Hale, Jerry Kiefer
Studies Of H₂O On Ss-Agi Surfaces: An Effective Pair Potential Model, Barbara N. Hale, Jerry Kiefer
Physics Faculty Research & Creative Works
Effective pair potential functions are used to study the adsorption of a water molecule on surfaces of β-AgI. The water molecule is represented by a rigid point charge ST-2 model and the AgI substrate by an array of point atoms with effective charge ±0.6e, Lennard-Jones cores, and ionic polarizabilities. Maximal binding energy surfaces and optimal H2O configurations are generated for the water molecule adsorbed on the rigid and unrelaxed basal and prism AgI faces. Adsorption of the H2O above a two layer ledge, an iodine vacancy, and an H2O trapped in the …
Angular Differential Cross Sections For Excitation Of Atomic Hydrogen To The N=2 Level By Proton Impact, John T. Park, Judith E. Aldag, Jerry Peacher, Jacob M. George
Angular Differential Cross Sections For Excitation Of Atomic Hydrogen To The N=2 Level By Proton Impact, John T. Park, Judith E. Aldag, Jerry Peacher, Jacob M. George
Physics Faculty Research & Creative Works
Differential cross sections for 15-145-keV proton impact excitation of atomic hydrogen to the n=2 level have been determined for center-of-mass scattering angles 0 to 1.2 mrad. The cross sections were obtained from an analysis of the angular distribution of protons which had lost an energy corresponding to the excitation of atomic hydrogen to its n=2 level. The differential cross sections obtained are in rather good agreement with available coupled-state calculations as well as the simpler Glauber-approximation calculations. However, at the larger scattering angles the cross sections obtained from the theoretical treatments appear to decrease more rapidly than the experimental data.
Potential Use Of Chemical Spot Test Method For Submicron Aerosol Sizing, Paul C. Yue, Josef Podzimek
Potential Use Of Chemical Spot Test Method For Submicron Aerosol Sizing, Paul C. Yue, Josef Podzimek
Physics Faculty Research & Creative Works
A submicron particle, which is too small to be observed in an optical microscope, may form an observable spot on a chemically prepared substrate of the collector. The size of the spot or "Liesegang circle" is related to the aerodynamic diameter of the particle through a magnification factor. This paper presents the experimental results of the study of this factor using sodium chloride aerosol in the size range of 0.5 to 2 pm which has not previously been studied. We calibrated a cylindrical centrifuge with known sized latex particles. A relationship between the aerodynamic diameter and the deposition length is …
More On Calculators In Beginning Physics Courses, Harry A. Brown
More On Calculators In Beginning Physics Courses, Harry A. Brown
Physics Faculty Research & Creative Works
No abstract provided.
Injection-Locked Dye Laser Pumped By A Xenon-Lon Laser, E. R. Carney, D. W. Fahey, Laird D. Schearer
Injection-Locked Dye Laser Pumped By A Xenon-Lon Laser, E. R. Carney, D. W. Fahey, Laird D. Schearer
Physics Faculty Research & Creative Works
Injection locking of a dye laser is reported for a 4-minor ring-cavity dye User pumped by a xenon-ion laser. Both a He-Ne laser and tunable CW dye laser were used as the injection sources. Copyright © 1980 by The Institute of Electrical and Electronics Engineers, Inc.
Large-Angle Electron-Photon Coincidence Experiment In Atomic Hydrogen, E. Weigold, L. Frost, K. (Kaare) J. Nygaard
Large-Angle Electron-Photon Coincidence Experiment In Atomic Hydrogen, E. Weigold, L. Frost, K. (Kaare) J. Nygaard
Physics Faculty Research & Creative Works
1s-2p excitation in hydrogen has been studied by observing the angular correlation of Lyman photons detected in coincidence with inelastically scattered electrons at 54.4 eV incident energy. The electron scattering angles ranged from 10°to 133°; the results at scattering angles larger than 20°cannot be explained by currently available theories. © 1980 The American Physical Society.
Nonequilibrium Thermodynamics Of Fuel Cells: Heat Release Mechanisms And Voltage, Gerald Wilemski
Nonequilibrium Thermodynamics Of Fuel Cells: Heat Release Mechanisms And Voltage, Gerald Wilemski
Physics Faculty Research & Creative Works
Nonequilibrium thermodynamics is used to analyze the spatial distribution of heat release mechanisms occurring in fuel cells operating under load in nonisothermal steady states. Novel contributions to heat release in the bulk electrolyte are found which are analogous to Peltier and Thomson effects in metallic conductors. Expresions for the heat release at individual electrodes are presented. An equation for the voltage of these cells is also derived. © 1980 American Institute of Physics.
Comment On “Cancellation Of Internal Forces”, Harry A. Brown
Comment On “Cancellation Of Internal Forces”, Harry A. Brown
Physics Faculty Research & Creative Works
No abstract provided.
Water And Ice Nucleation Sites From Ion Implantation Of Silicon, William H. Stlnebaugh, Don M. Sparlin, James L. Kassner
Water And Ice Nucleation Sites From Ion Implantation Of Silicon, William H. Stlnebaugh, Don M. Sparlin, James L. Kassner
Physics Faculty Research & Creative Works
Ion implantation has a substantial effect on the heterogeneous nucleation of water and ice. An enhancement of water nucleation and a suppression of ice nucleation occurred for samples of silicon implanted with ions of various species and dosage. These effects were noticeable only for samples implanted with ion doses approaching or exceeding the critical dose necessary to produce amorphous silicon. The behavior of the water droplet and ice crystal growth can be related to the amount of ion produced damage to the substrate surface. The nature of the damage can be controlled by variation of the incident ion species, dose, …
Total Penning Ionization Cross Sections Of Cd And Zn For He(2 ³S1) Atoms, D. W. Fahey, William F. Parks, Laird D. Schearer
Total Penning Ionization Cross Sections Of Cd And Zn For He(2 ³S1) Atoms, D. W. Fahey, William F. Parks, Laird D. Schearer
Physics Faculty Research & Creative Works
The total Penning ionization cross sections for Cd and Zn for He(2 3S1) atoms have been measured. The method used was that of Penning ion collection from a vapor cell through which a He(2 3S1) beam was passed. The beam energy was 66 meV with a velocity spread of 45%. The measured cross sections were 106(±22) and 35(±7) Å2 for the Cd and Zn targets, respectively. © 1980 American Institute of Physics.
Nickel Carbide: Its Formation And Characterization By Transmission Electron Diffraction, Auger Electron Spectroscopy And Electron Spectroscopy For Chemical Analysis, J. Kleefeld, L. L. Levenson
Nickel Carbide: Its Formation And Characterization By Transmission Electron Diffraction, Auger Electron Spectroscopy And Electron Spectroscopy For Chemical Analysis, J. Kleefeld, L. L. Levenson
Physics Faculty Research & Creative Works
Nickel carbide (NiC3) films are formed by the carburization of nickel films in CO at 350°C. The presence of Ni3C is demonstrated by transmission electron diffraction. The carbon Auger electron signal of Ni3C is identical with the carbon Auger spectra attributed to Ni3C by previous authors. The position of the C 1s electron spectroscopy for chemical analysis peak is within 1 eV of the C 1s peak produced by graphite. The grain size of polycrystalline Ni3C is significantly larger than the grain size of the nickel film from which it is grown. © 1979.
Electron Drift Velocities In N2, Co2, And (N 2+Co2) Laser Mixtures, Rafael A. Sierra, Howard L. Brooks, Kaare J. Nygaard
Electron Drift Velocities In N2, Co2, And (N 2+Co2) Laser Mixtures, Rafael A. Sierra, Howard L. Brooks, Kaare J. Nygaard
Physics Faculty Research & Creative Works
A time-of-flight technique has been used to obtain electron drift velocities in N2, CO2, and N2-CO2 mixtures covering the E/N range 3-93 Td. In the case of the pure gases, excellent agreement with previous work is obtained over the entire E/N range. The mixtures, which are of laser importance, have not been studied previously.
The Hanle Effect In Penning-Excited Ions, D. W. Fahey, William F. Parks, Laird D. Schearer
The Hanle Effect In Penning-Excited Ions, D. W. Fahey, William F. Parks, Laird D. Schearer
Physics Faculty Research & Creative Works
A thermal beam of helium (23S1) metastable atoms was used to excite coherently the 2P3/2 levels of Ca, Sr and Ba in a Penning ionizing collision. The coherent excitation of the ions appears as a linear polarization of the optical emission from the excited ions. The degree of linear polarization is 5.5, 3.5 and 0.5% for Ca, Sr and Ba, respectively, with the polarization parallel to the beam direction. Hanle effect signals from the 2P3/2 level of Sr were observed and the radioactive decay rate measured.
Conductive Strontium Titanate Layers Produced By Boron-Ion Implantation, Connie M. Cooper, P. S. Nayar, Edward Boyd Hale, Robert Gerson
Conductive Strontium Titanate Layers Produced By Boron-Ion Implantation, Connie M. Cooper, P. S. Nayar, Edward Boyd Hale, Robert Gerson
Physics Faculty Research & Creative Works
The ion implantation of boron has been found to be an effective method for increasing the conductivity of strontium titanate. A highly conductive layer was formed by implantations at doses of 3.6x1016 to 1.0x1017 ions/cm2, using an accelerating voltage of 100 kV, corresponding to a boron range of about 300 nm. The conductivity of the implanted layer was found to be further enhanced by about four orders of magnitude after annealing at 225 °C. The surface resistivity attained was typically 1000 Ω/square at room temperature. The resistance increased with rising temperature between 77 and 500 K. All samples were found …
Doubly Differential Cross Sections For Proton-Impact Ionization Of Argon, Don H. Madison, Steven Trent Manson
Doubly Differential Cross Sections For Proton-Impact Ionization Of Argon, Don H. Madison, Steven Trent Manson
Physics Faculty Research & Creative Works
Proton-impact-ionization cross sections for argon which are differential in the energy and angle of the ejected electron have been calculated within the framework of the Born approximation using both Hartree-Slater and Hartree-Fock wave functions for the ejected electron. Results of the two types of calculations are compared with each other and with experiment. Differential cross sections for all five sub shells of argon are examined and particular attention is given to some interesting features of the K-shell cross sections. The range of applicability of the theoretical models is discussed.
Dissociative Excitation Of Hgbr2 In Collisions With A Beam Of Metastable Nitrogen, D. W. Fahey, Laird D. Schearer
Dissociative Excitation Of Hgbr2 In Collisions With A Beam Of Metastable Nitrogen, D. W. Fahey, Laird D. Schearer
Physics Faculty Research & Creative Works
No abstract provided.