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Full-Text Articles in Physics
Two- And Three-Body Electron-Ion Recombination In Carbon Dioxide, Ian M. Littlewood, M. C. Cornell, B. K. Clark, Kaare J. Nygaard
Two- And Three-Body Electron-Ion Recombination In Carbon Dioxide, Ian M. Littlewood, M. C. Cornell, B. K. Clark, Kaare J. Nygaard
Physics Faculty Research & Creative Works
The electron-ion recombination rate in carbon dioxide was measured as a function of electric field strength and gas pressure. The separate effects of two- and three-body recombination was observed, and the respective rate constants obtained. The results indicate that three-body recombination is dominant at low field strengths for gas pressures above 1 atm, whereas two-body recombination is dominant at high field strengths.
Reactive Scattering Cell For Atomic Hydrogen And Deuterium, John T. Park, E. Redd, T. J. Kvale, E. Rille
Reactive Scattering Cell For Atomic Hydrogen And Deuterium, John T. Park, E. Redd, T. J. Kvale, E. Rille
Physics Faculty Research & Creative Works
A design for a high-temperature reactive scattering cell for atomic hydrogen and atomic deuterium is described. At approximately 2700 K a dissociation of the molecular target species of over 95% has been obtained. The lifetime of 340 h of operation is sufficient for precision, long-time, differential cross-section measurements.
Electron Drift Velocities In Gas Mixtures Of He, N2, And Co 2, Michael C. Cornell, Ian M. Littlewood, Howard L. Brooks, Kaare J. Nygaard
Electron Drift Velocities In Gas Mixtures Of He, N2, And Co 2, Michael C. Cornell, Ian M. Littlewood, Howard L. Brooks, Kaare J. Nygaard
Physics Faculty Research & Creative Works
An electron swarm experiment has been used to obtain electron drift velocities in the He:CO2:N2 mixtures 0:1:1, 3:1:2, and 3:1:1. The E/N range of 3 to 57 Td was studied with total gas pressure varied from 50 to 200 Torr. These particular mixtures have not been previously studied experimentally. Good agreement is observed between theoretical calculations and experimental data.
Isotope Effect And Momentum-Transfer Scaling In The Elastic-Scattering Differential Cross Sections For Hydrogen-Isotope Collision Systems, Eduard P. Rille, Jerry Peacher, Denver G. Seely, Thomas J. Kvale, E. Redd, D. M. Blankenship, John T. Park
Isotope Effect And Momentum-Transfer Scaling In The Elastic-Scattering Differential Cross Sections For Hydrogen-Isotope Collision Systems, Eduard P. Rille, Jerry Peacher, Denver G. Seely, Thomas J. Kvale, E. Redd, D. M. Blankenship, John T. Park
Physics Faculty Research & Creative Works
A projectile-dependent isotope effect was found for the elastic-scattering differential cross sections in the hydrogen-isotope collision systems. All four differential cross sections lie on a common curve if they are divided by the square of the reduced mass and plotted against momentum transfer. The experimental results are in satisfactory agreement with a simple Glauber-approximation calculation.
Electron Capture Cross Sections For Tih⁴⁺, H. Sato, M. Kimura, A. E. Wetmore, Ronald E. Olson
Electron Capture Cross Sections For Tih⁴⁺, H. Sato, M. Kimura, A. E. Wetmore, Ronald E. Olson
Physics Faculty Research & Creative Works
Electron capture cross sections have been computed for Ti4++H to Ti3++H+ and Ti3++H+ to Ti4++H, where the reactants were in their ground states. The energy range investigated was 0.1 to 10 keV amu-1. The impact parameter perturbed-stationary-state method incorporating electron translation factors were used to calculate the cross sections. The molecular wavefunctions were generated using the pseudo-potential method. At 1 keV amu-1 ( nu rel=4.4*107 cm s-1), representative electron capture cross sections for the Ti4++H and Ti3++H+ reactions are 2*10-15 cm 2 and 1*10-17 cm2, respectively. An …
Charge Transfer And Ionisation Processes Involving Multiply Charged Ions In Collision With Atomic Hydrogen, D. J.W. Hardie, Ronald E. Olson
Charge Transfer And Ionisation Processes Involving Multiply Charged Ions In Collision With Atomic Hydrogen, D. J.W. Hardie, Ronald E. Olson
Physics Faculty Research & Creative Works
Total cross sections are presented for the charge transfer reaction Xq++H(1s) to X(q-1)+H+ and ionization process Xq++H(1s) to Xq++H+-e-. Here Xq+ is a fully or partially stripped ion. The collision energy range lies between 25-200 keV amu-1. Cross sections are also given for charge transfer into particular ionic n states and n, l states for energies of 25 and 50 keV amu-1, where Xq+=H+, He 2+, C6+, O8+. The calculations were performed by the classical trajectory Monte Carlo method of Olson and …
Composition Of The Critical Nucleus In Multicomponent Vapor Nucleation, Gerald Wilemski
Composition Of The Critical Nucleus In Multicomponent Vapor Nucleation, Gerald Wilemski
Physics Faculty Research & Creative Works
No abstract provided.
Study Of Prenucleation Ion Clusters: Correlation Between Ion Mobility Spectra And Size Distributions, Sung-Ho Suck Salk, Donald E. Hagen, James L. Kassner
Study Of Prenucleation Ion Clusters: Correlation Between Ion Mobility Spectra And Size Distributions, Sung-Ho Suck Salk, Donald E. Hagen, James L. Kassner
Physics Faculty Research & Creative Works
Additional studies regarding our earlier electrothermodynamic theory are presented. Comparisons to recent expansion cloud chamber ion mobility measurements are made, indicating general agreement with observations. This theory predicts more stable and ordered structure for prenucleation ion-water cluster systems than accounted for by the classical Thomson's theory. In the limiting case of the dielectric constant ε = 1, our monopole electrostatic energy term contributed by the foreign ion center precisely converges to that of Thomson. Predicted ion cluster size distributions are found to correlate well with ion cluster size spectra obtained from the ion mobility measurements of hydrated ion clusters and …
Momentum-Transfer Scaling In Hydrogen-Isotope Collision Systems, Eduard P. Rille, Jerry Peacher, Thomas J. Kvale, E. Redd, D. M. Blankenship, John T. Park
Momentum-Transfer Scaling In Hydrogen-Isotope Collision Systems, Eduard P. Rille, Jerry Peacher, Thomas J. Kvale, E. Redd, D. M. Blankenship, John T. Park
Physics Faculty Research & Creative Works
The differential cross sections for excitation of atomic hydrogen isotopes to their n=2 states by proton or deutron impact are found to follow a simple scaling relationship. The momentum-transfer-scaled differential excitation cross sections, for a projectile velocity of 1.26 a.u., produce one differential cross-section curve for all four possible hydrogen-isotope collision systems. The experimental results are in excellent agreement with our Glauber-approximation calculations.
Structural Studies Of Low Temperature Ice Iₕ Using A Central Force Potential Model, Peter W. Deutsch, Barbara N. Hale, Richard C. Ward, Donald A. Reago Jr.
Structural Studies Of Low Temperature Ice Iₕ Using A Central Force Potential Model, Peter W. Deutsch, Barbara N. Hale, Richard C. Ward, Donald A. Reago Jr.
Physics Faculty Research & Creative Works
The revised central force potentials of Stillinger and Rahman [J. Chem. Phys. 68, 666 (1978)] are used to study the binding energy, structure, and multipole moments of a periodic ice Ih sample with a unit cell of 192 water molecules. The initial configuration for the unit cell has each oxygen in a wurtzite structure and intramolecular H-O-H angles symmetrically positioned in the tetrahedral O-O-O angles. Hydrogens are placed such that the total dipole moment for the unit cell is zero and the diagonal quadrupole moments are small (≲ 10-28 esu cm2). Subject to these restrictions, a …
Exciton Trapping And Sensitized Luminescence: A Generalized Theory For All Trap Concentrations, Vasudev M. Kenkre, Paul Ernest Parris
Exciton Trapping And Sensitized Luminescence: A Generalized Theory For All Trap Concentrations, Vasudev M. Kenkre, Paul Ernest Parris
Physics Faculty Research & Creative Works
The generalized-master-equation theory of sensitized luminescence in molecular crystals is extended to cover arbitrary guest concentrations by making use of a recently introduced formalism. Central to the formalism is a quantity termed the ν function, which is an ensemble average of the sum of host propagators over guest-influenced host sites. A variety of experimentally relevant sensitized luminescence observables, such as the host (and guest) luminescence intensity, the quantum yields, and the energy-transfer rates are simply related to the ν function. It is shown how the latter can be calculated for exciton motion possessing an arbitrary degree of coherence, dimensionality, and …
Homogeneous Nucleation Rate Measurements For Water Over A Wide Range Of Temperature And Nucleation Rate, Ronald C. Miller, Robert J. Anderson, James L. Kassner, Donald E. Hagen
Homogeneous Nucleation Rate Measurements For Water Over A Wide Range Of Temperature And Nucleation Rate, Ronald C. Miller, Robert J. Anderson, James L. Kassner, Donald E. Hagen
Physics Faculty Research & Creative Works
An expansion cloud chamber was used to measure the homogeneous nucleation rate for water over a wide range of temperature from 230-290 K and nucleation rates of 1-106 drops cm-3 s-1. The comprehensive and extensive nature of this data allows a much more detailed comparison between theory and experiment than has previously been possible. The expansion chamber technique employs continuous pressure measurement and an adiabatic pulse of supersaturation to give the time history of supersaturation and temperature during the nucleation. The resulting drop concentration is determined using photographic techniques. The experimental observations are presented in tabular …
Thermal Decomposition Kinetics Of Iodine‐Doped Polyacetylene In Vacuum, J. ‐E Osterholm, H. Yasuda, L. L. Levenson
Thermal Decomposition Kinetics Of Iodine‐Doped Polyacetylene In Vacuum, J. ‐E Osterholm, H. Yasuda, L. L. Levenson
Physics Faculty Research & Creative Works
The thermal stability of iodine‐doped polyacetylene films, (CHIy)x, has been studied by means of electrical conductivity measurements, measurements on weight loss, and mass spectrometric analysis of desorbing species. When heated between room temperature and 125°C in vacuum, these films proved to be of poor thermal stability, being unstable at temperatures above 20°C. During the thermal treatments, molecular iodine desorbs from the films, resulting in an appreciable dopant weight loss with accompanying decrease in the electrical conductivity. The decomposition process does not follow simple kinetics. Copyright © 1983 John Wiley & Sons, Inc.
Molecular Treatment Of Charge Transfer In Li+ +Ca Collisions, M. Kimura, H. Sato, Ronald E. Olson
Molecular Treatment Of Charge Transfer In Li+ +Ca Collisions, M. Kimura, H. Sato, Ronald E. Olson
Physics Faculty Research & Creative Works
The perturbed-stationary-state method, appended with electron translation factors, has been applied to charge transfer in Li+ +Ca collisions for energies from 0.1 to 20 keV/amu. The Born-Oppenheimer wave functions and eigenvalues were generated using the pseudopotential technique, which reduced the many-electron system to a simpler two-electron problem. The molecular ground-state X +1 is calculated to be bound and has the potential-well parameters Re=6.20a0, De=1.11 eV, e=235 cm-1, and Be=0.263 cm-1. From the scattering computations, a representative value for the charge-transfer cross section is 4x10-15 cm2 at 5 keV/amu. The cross section decreases rapidly as the energy is reduced below 1 …
Homogeneous Nucleation Of Toluene, John L. Schmitt, R. A. Zalabsky, G. W. Adams
Homogeneous Nucleation Of Toluene, John L. Schmitt, R. A. Zalabsky, G. W. Adams
Physics Faculty Research & Creative Works
The authors have used a fast expansion chamber to measure the homogeneous nucleation rate of toluene as a function of temperature and supersaturation. The measured nucleation rate ranges from 102 to 105 drops/cm3 s over a temperature range of 215-267 K. The measurements are compared with the "classical" nucleation theory and with the RKC theory. The inclusion of the RKC replacement factor brings the data into good agreement with theory using physically realistic values of the surface tension and the sticking coefficient. An empirical curve fit to the data is presented as well as a full listing of the thermodynamic …
Universal Stationary-Phase Treatment Of Far-Wing And Excimer Spectral Line Shapes, Ronald James Bieniek, T. J. Streeter
Universal Stationary-Phase Treatment Of Far-Wing And Excimer Spectral Line Shapes, Ronald James Bieniek, T. J. Streeter
Physics Faculty Research & Creative Works
When two atoms are in proximity, their resonance lines are broadened because of the formation of molecular potentials, between which photon transitions can occur. The level of experimental refinement in measuring excimer and collisional far-wing spectra calls for interpretive theoretical methods that accurately treat the observed structure in line shapes. Of particular interest are satellites and undulations, for they can give much information on intermolecular potentials. We derive an expression for T-matrix elements, based on JWKB wave functions and stationary-phase techniques, that is universally applicable to situations with one, two, or more Condon points. Each transition point is treated individually, …
Collisions Of Fast Highly Charged Ions In Gas Targets: Ionization, Recoil-Ion Production, And Charge Transfer, A. S. Schlachter, K. H. Berkner, H. F. Beyer, W. G. Graham, W. Groh, R. Mann, A. Müller, Ronald E. Olson, R. V. Pyle, J. W. Stearns, J. A. Tanis
Collisions Of Fast Highly Charged Ions In Gas Targets: Ionization, Recoil-Ion Production, And Charge Transfer, A. S. Schlachter, K. H. Berkner, H. F. Beyer, W. G. Graham, W. Groh, R. Mann, A. Müller, Ronald E. Olson, R. V. Pyle, J. W. Stearns, J. A. Tanis
Physics Faculty Research & Creative Works
Electron-capture, ionization, and recoil-ion-production cross-sections are measured and calculated for fast highly charged projectiles in hydrogen and rare-gas targets. Recoil-ion-production cross-sections are found to be large; the low energy and high charge states of the recoil ions make them useful for subsequent collision studies. © 1983 IOP Publishing Ltd.
On The Schrödinger Spin‐Exchange Ferromagnet, Harry A. Brown
On The Schrödinger Spin‐Exchange Ferromagnet, Harry A. Brown
Physics Faculty Research & Creative Works
The thermodynamic behavior of a ferromagnet whose interactions are described by the Schrödinger spin‐exchange operator is investigated. The transition temperatures, magnetization, susceptibility, exchange energy, heat capacity, and entropy are calculated for general spin and lattice coordination number using the constant‐coupling approximation. Both first‐ and second‐order phase transitions are found. Comparison with some results of the high‐temperature expansion method shows some qualitative agreement. Copyright © 1983 WILEY‐VCH Verlag GmbH & Co. KGaA
Ion-Atom Differential Cross Sections At Intermediate Energies, Ronald E. Olson
Ion-Atom Differential Cross Sections At Intermediate Energies, Ronald E. Olson
Physics Faculty Research & Creative Works
The classical-trajectory Monte Carlo method has been used to calculate H++H(1s) electron-capture and ionization differential cross sections in the range 25-200 keV. The results indicate the importance of including excited product states to describe the small-angle electron-capture scattering. Angular scattering of the electron removed by the ionization process has been studied as a function of ejected-electron velocity ve. The classical calculations are in reasonable agreement with coupled-channel results of Shakeshaft [Phys. Rev. A 18, 1930 (1978)] as to the "electron capture to the continuum" (ECC) component of the ionization process where this term is defined as the ejected electron being …
Ion Scattering From State-Selected Rydberg Atoms, G. A. Kohring, A. E. Wetmore, Ronald E. Olson
Ion Scattering From State-Selected Rydberg Atoms, G. A. Kohring, A. E. Wetmore, Ronald E. Olson
Physics Faculty Research & Creative Works
Classical-trajectory Monte Carlo calculations have been performed for collisions of protons with state-selected hydrogenic Rydberg atoms. The examples investigated were Rydberg atoms in the n=10, l=9 level with ml=0 and 9. The collision velocity range was 0.1 to 1.0 a.u. (2.2x107 to 2.2x108 cm/s). The ionization cross sections were found to be relatively insensitive to changes in the ml levels. However, the charge-transfer cross sections showed considerable enhancement if the Rydberg electron is orientated in a plane which is parallel to the direction of the incident projectile. © 1983 The American Physical Society.
Vibrational-Rotational Deexcitation Of Hf In Collision With He, Ronald James Bieniek
Vibrational-Rotational Deexcitation Of Hf In Collision With He, Ronald James Bieniek
Physics Faculty Research & Creative Works
State-to-state cross sections are reported for vibrational-rotational transitions for HF in collisions with He, at collisional energies of 0.5 and 1.0 eV. These were computed within the infinite-order sudden (IOS) approximation using adiabatic, distorted-wave techniques. Values are tabulated for the vibrational-rotational deexcitation sequences (v,j)→(v-1, 0), with v=1, 2, 3, 4 and j=0-40. These quenching cross sections can be used in conjunction with IOS factorization formulas to compute VRT cross sections for final rotational states other jf=0. In addition to IOS results, vibrational quenching cross sections were computed using the much more simple breathing-sphere technique. The breathing-sphere results compare favorably to …
Nanosecond Optical Transmission Studies Of Laser Annealing In Ion-Implanted Silicon-On-Sapphire, M. C. Lee, H. W. Lo, A. Aydinli, G. J. Trott, A. Compaan, Edward Boyd Hale
Nanosecond Optical Transmission Studies Of Laser Annealing In Ion-Implanted Silicon-On-Sapphire, M. C. Lee, H. W. Lo, A. Aydinli, G. J. Trott, A. Compaan, Edward Boyd Hale
Physics Faculty Research & Creative Works
Time-resolved optical transmission has been studied using 633 and 514 nm CW probes on ion-implantation-amorphized silicon-on-sapphire during annealing by a 10 nsec, ⊥ J/cm2 pulse at either 532 nm or 485 nm. As recrystallization sets in the transmitted signal at 514 nm rises by ⊥ 103 in ⊥ 60 nsec and provides a measure of regrowth velocity. Beyond 200 nsec the much slower transmission rise is used to provide an estimate of the Si cooling rate. The difference in transmission observed between initially crystalline and initially amorphous Si provide an estimate of the latent heat of recrystallization of the amorphous …