Open Access. Powered by Scholars. Published by Universities.®

Physical Sciences and Mathematics Commons™

Open Access. Powered by Scholars. Published by Universities.®

Physics

Institution
Keyword
Publication Year
Publication
Publication Type
File Type

Articles 33481 - 33510 of 36553

Full-Text Articles in Physical Sciences and Mathematics

Rotational Effects In The Vuv Continuum Of H2, H. Schmoranzer, T. Noll, T. Noll, E. Roueff, H. Abgrall, Ronald James Bieniek Jun 1990

Rotational Effects In The Vuv Continuum Of H2, H. Schmoranzer, T. Noll, T. Noll, E. Roueff, H. Abgrall, Ronald James Bieniek

Physics Faculty Research & Creative Works

The effects of rotation-vibration interaction and of rotational coupling between the B 2p 1Σu+ and C 2p 1Πu electronic states on the B-X continuum of H2 were investigated spectroscopically using monochromatized synchrotron radiation for selective excitation of rovibronic states. The perturbed continuum intensities observed for the first time agree well with close-coupling calculations also performed. © 1990 IOP Publishing Ltd.

Go to article

Intercellular Structure In A Many-Celled Magnetotactic Prokaryote, Frank G. Rodgers, Richard P. Blakemore, Nancy A. Blakemore, Richard B. Frankel, Dennis A. Bazylinski, Denise Maratea, Christine Rodgers Jun 1990

Intercellular Structure In A Many-Celled Magnetotactic Prokaryote, Frank G. Rodgers, Richard P. Blakemore, Nancy A. Blakemore, Richard B. Frankel, Dennis A. Bazylinski, Denise Maratea, Christine Rodgers

Physics

A many-called magnetotactic prokaryote obtained from brackish water was observed to possess intercellular connections at points of contact between the outer membranes of constituent cells. Each aggregate organism consisted of 10 to 30 individual Gram-negative cells containing material with the appearance of poly-β-hydroxybutyrate and magnetosomes of unusual arrangement, structure and composition. The aggregate, which possessed prokaryotic-type flagella arranged at the outwards surfaces of each cell, showed motility indicative of co-ordination between individual component cells. These results suggest that this organism could be a multicellular prokaryote.

Go to article

Coupled-Channel Optical Calculation Of Electron-Hydrogen Scattering: The Distorted-Wave Optical Potential, Igor Bray, Don H. Madison, Ian E. Mccarthy Jun 1990

Coupled-Channel Optical Calculation Of Electron-Hydrogen Scattering: The Distorted-Wave Optical Potential, Igor Bray, Don H. Madison, Ian E. Mccarthy

Physics Faculty Research & Creative Works

The coupled-channel optical method solves a set of coupled momentum-space integral equations for a finite set of reaction channels. The remaining channels, including the target continuum, are described by the polarization potential operator, which formally depends on the full three-body state vectors for these channels. The distorted-wave optical potential makes the distorted-wave Born approximation for these state vectors, using exact target states. No other approximation is made. Calculations and comparison with experiment are reported for total ionization cross sections and asymmetries, total excitation cross sections, entrance-channel phenomena, and the coupled 1s,2s,2p channels, at a range of energies.

Go to article

Correlation-Dimension Calculations For Broadband Intensity Fluctuations In Emission From A Heavily Saturated Source Of Amplified Spontaneous Emission, B. Das, Alfonso M. Albano, N. B. Abraham Jun 1990

Correlation-Dimension Calculations For Broadband Intensity Fluctuations In Emission From A Heavily Saturated Source Of Amplified Spontaneous Emission, B. Das, Alfonso M. Albano, N. B. Abraham

Physics Faculty Research and Scholarship

Broadband intensity fluctuations from a heavily saturated source of amplified spontaneous emission (ASE) operating on the 3.51-μm transition of xenon show no evidence of a dynamical origin represented by a low-dimensional underlying chaotic attractor. The broadband coupled-mode fluctuations in ASE thus seem to be stochastic when contrasted with the recently reported deterministic nature of similar broadband fluctuations of single-mode lasers operating on the same transition.

Go to article

Two-Photon Ionization Of The Ar Atom And Detachment Of The F- Ionv, Cheng Pan, Bo Gao, Anthony F. Starace Jun 1990

Two-Photon Ionization Of The Ar Atom And Detachment Of The F- Ionv, Cheng Pan, Bo Gao, Anthony F. Starace

Anthony F. Starace Publications

Theoretical calculations of the two-photon ionization cross section of argon and of the two-photon detachment cross section of the negative fluorine ion are presented for the energy region from threshold to the single-photon ionization or detachment threshold. Detailed analyses are presented of the effects of various kinds of electron correlations, whose contributions to the two-photon transition amplitudes are evaluated using variationally stable procedures to sum implicitly over intermediate states. These variationally stable procedures enable us to give much more reliable predictions in the region of the first few intermediate-state resonances in argon than were provided by previous calculations of one …

Go to article

Mars And Beyond: The Solar System Beckons, Frank J. Redd May 1990

Mars And Beyond: The Solar System Beckons, Frank J. Redd

Faculty Honor Lectures

To space zealots, 1989 was the year the drought ended. The space shuttle was operational again; Voyager's grand reconnaissance of the Solar System climaxed with the glorious encounter with the planet Neptune and its startling moon, Triton; the launches of the Magellan spacecraft to Venus and the Gallileo to Jupiter broke a decade long hiatus in the launch of U.S. planetary missions; and, for the first time in over twenty years, a U.S. president announced a daring new initiative in human exploration with the goal of first returning humans to the Moon, then going on to Mars.

Go to article

Total-Energy And Pressure Calculations For Random Substitutional Alloys, Duane D. Johnson, D. M. Nicholson, F. J. Pinski, B. L. Györffy, G. M. Stocks May 1990

Total-Energy And Pressure Calculations For Random Substitutional Alloys, Duane D. Johnson, D. M. Nicholson, F. J. Pinski, B. L. Györffy, G. M. Stocks

Duane D. Johnson

We present the details and the derivation of density-functional-based expressions for the total energy and pressure for random substitutional alloys (RSA) using the Korringa-Kohn-Rostoker Green’s-function approach in combination with the coherent-potential approximation (CPA) to treat the configurational averaging. This includes algebraic cancellation of various electronic core contributions to the total energy and pressure, as in ordered-solid muffin-tin-potential calculations. Thus, within the CPA, total-energy and pressure calculations for RSA have the same foundation and have been found to have the same accuracy as those obtained in similar calculations for ordered solids. Results of our calculations for the impurity formation energy, and …

Go to article

Magnetism And Anisotropy Of Tb/Fe Multilayers, Z.S. Shan, David J. Sellmyer May 1990

Magnetism And Anisotropy Of Tb/Fe Multilayers, Z.S. Shan, David J. Sellmyer

David Sellmyer Publications

Studies of the layer-thickness dependence of hysteresis loops for Tb/Fe compositionally modulated films (CMF) are reported. The characteristics of magnetic properties, such as magnetization and uniaxial anisotropy, which depend on the FE layer thickness, can be interpreted in terms of the compositional dependence of magnetic properties of the constituent subnetworks and the spatial distribution of the constituent atoms. The magnetic properties of Tb/Fe CMF are analyzed with a micromagnetic model, and the behavior of the anisotropy and constituent magnetization near the compensation point is discussed. Journal of Applied Physics is copyrighted by The American Institute of Physics.

Go to article

Magnetic And Structural Properties Of Cocrta Films And Multilayers With Cr, David J. Sellmyer, D. Wang, J.A. Christner May 1990

Magnetic And Structural Properties Of Cocrta Films And Multilayers With Cr, David J. Sellmyer, D. Wang, J.A. Christner

David Sellmyer Publications

We report our studies of epitaxial growth of CoCrTa films on Cr underlayers and the properties of CoCrTa/Cr multilayers. The coercivity, Hc, strongly depends on Ta composition, sputtering conditions, and the thicknesses of the magnetic layer and Cr underlayer. An Hcvalue of 1300 Oe was obtained for a Ta composition of 2 at. %, a Cr underlayer thickness of 4000 Å, and a magnetic layer thickness of 400 Å. The x-ray data show that the high Hc occurs when crystallites of the Cr underlayer and CoCrTa layer are aligned with the Cr (200) and CoCrTa …

Go to article

The Structure And Magneto-Optic Properties Of Mnal-Based Thin Films, J.X. Shen, Roger D. Kirby, David J. Sellmyer May 1990

The Structure And Magneto-Optic Properties Of Mnal-Based Thin Films, J.X. Shen, Roger D. Kirby, David J. Sellmyer

Roger Kirby Publications

We have measured the magnetization and magneto-optic Kerr rotation of sputtered thin films of Mn-Al-Cu ternary alloys over a wide composition range and for substrate temperatures between 25 and 450 °C. Magnetization and x-ray diffraction measurements suggest that our films are a mixture of the ferromagnetic kappa (κ) phase of MnAl and a highly paramagnetic amorphous phase. Room-temperature magneto-optic measurements on these films show a saturation polar Kerr rotation of up to 0.12° with little wavelength dependence.

Go to article

Fabrication Of Ferromagnetic And Antiferromagnetic Chromium Oxides By Organometallic Chemical Vapor Deposition, Peter A. Dowben, Yoon Gi Kim, S. Baral-Tosh, G.O. Ramseyer, Chanyong Hwang, M. Onellion May 1990

Fabrication Of Ferromagnetic And Antiferromagnetic Chromium Oxides By Organometallic Chemical Vapor Deposition, Peter A. Dowben, Yoon Gi Kim, S. Baral-Tosh, G.O. Ramseyer, Chanyong Hwang, M. Onellion

Peter Dowben Publications

We have been able to fabricate CrO2 and Cr2O3 from ultraviolet photolytic and plasma-assisted decomposition of Cr(CO) 6 in an oxygen carrier gas. The composition of these films is uniform in composition and contains little contamination. Using magneto-optic Kerr effect measurements, we have been able to demonstrate that the CrO2 films are ferromagnetic.

Go to article

The Chemistry Of The Gadolinium-Nickel Interface, D. Lagraffe, Peter A. Dowben, M. Onellion May 1990

The Chemistry Of The Gadolinium-Nickel Interface, D. Lagraffe, Peter A. Dowben, M. Onellion

Peter Dowben Publications

Gadolinium overlayers on Ni(111) have been studied by angle resolved photoemission, angle resolved AES, LEED, and RHEEB. We have observed pronounced interdiffusion of nickel with the gadolinium overlayer at temperatures as low as 150 K. This is in marked contrast with gadolinium overlayers on Cu(108) where substantial interdiffusion is not observed until 360 K, but is consistent with studies of ytterbium on nickel. [A. Nilsson, B Eriksson, N. Martenssom, J. N. Andersen, and J. Onsgaard, Phys. Rev. B 38,10357, ( 1988) and I. Chorkendorff, K. Onsgaard, J. Schmidt-May and R. Nyholm, Surf. Sci. 160, 587, (1985) .] There is a …

Go to article

Effect Of Second-Order Exchange In Electron-Hydrogen Scattering, Don H. Madison, Igor Bray, Ian E. Mccarthy May 1990

Effect Of Second-Order Exchange In Electron-Hydrogen Scattering, Don H. Madison, Igor Bray, Ian E. Mccarthy

Physics Faculty Research & Creative Works

The electron-hydrogen scattering problem has been a nemesis to theoretical atomic physicists due to the fact that even the most sophisticated of theoretical calculations, both perturbative and nonperturbative, do not agree with experiment. The current opinion is that the perturbative approach cannot be used for this problem since recent second-order calculations are not in agreement with the experimental data and higher-order calculations are deemed impractical However, these second-order calculations neglected second-order exchange. We have now added exchange to the second-order calculation and have found that the primary source of disagreement between experiment and theory for intermediate energies is attributable not …

Go to article

Ordering Of Metal Overlayers On Metal Substrates Studied Using Atom Beam Scattering, G. Vidali, C.W. Hutchings, Peter A. Dowben, M. Karimi, C. Moses, M. Foresti May 1990

Ordering Of Metal Overlayers On Metal Substrates Studied Using Atom Beam Scattering, G. Vidali, C.W. Hutchings, Peter A. Dowben, M. Karimi, C. Moses, M. Foresti

Peter Dowben Publications

We will illustrate how atom beam scattering (ABS) can be used to study the growth and ordering of adsorption of Hg on Cu(001). At low coverage (less than 2% of a monolayer), we obtain that the scattering cross section of He with (adsorbed) Hg is about 50 Å2. We find that mercury forms two stable phases on Cu(001) in the temperature range between 200 and 330 K, a c (2 x 2) and a high density c (4 x 4) phase. From ABS diffraction data, we can deduce the corrugation of the surface electron charge density of the …

Go to article

The Effect Of Lateral Interactions On The Thermal Desorption Of N2 From Ni(100), Shikha Varma, Peter A. Dowben May 1990

The Effect Of Lateral Interactions On The Thermal Desorption Of N2 From Ni(100), Shikha Varma, Peter A. Dowben

Peter Dowben Publications

We have investigated the desorption of N2 from Ni(100) using thermal desorption spectroscopy (TDS). A modified Polanyi-Wigner equation has been used to obtain the desorption energy and the preexponential factor, both of which depend on the coverage of the adsorbate. We show that there is a large lateral interaction among the adlayer molecules when N2 goes down as ordered c (2 X 2) on Ni. In addition, the overlayer ordering, in the thermal desorption process, is observed to affect the thermal desorption spectra.

Go to article

Selective Area Deposition Of Conducting Palladium Films On Polyimide Resins, Yoon-Gi Kim, S. Bialy, R.W. Miller, J.T. Spencer, Peter A. Dowben, Saswati Datta May 1990

Selective Area Deposition Of Conducting Palladium Films On Polyimide Resins, Yoon-Gi Kim, S. Bialy, R.W. Miller, J.T. Spencer, Peter A. Dowben, Saswati Datta

Peter Dowben Publications

We have demonstrated that the selective area deposition of palladium on polyimide substrates i s possible through the U.V. photolysis of (π - a l l y 1) (π –cyclopentadieny1) palladium. This photolytic deposition process did not result in any apparent damage to either the Ultem 1000 (polyetherimide) or Kapton substrates (polyimide substrates). The resistivity of the palladium films (< 0.1 um) suggests that the films are porous.

Go to article

Magnetic Ordering Of Tb Overlayers On Ni(Ll1), D. Lagraffe, A. Miller, Peter A. Dowben, M. Onellion May 1990

Magnetic Ordering Of Tb Overlayers On Ni(Ll1), D. Lagraffe, A. Miller, Peter A. Dowben, M. Onellion

Peter Dowben Publications

The 5p3/2 to 5p1/2 shallow core level branching ratios in different - photoemission geometries provide a measure of the magnetic ordering in rare earth overlayers as a result of final state effects in photoemission. This 5p level anisotropy can be used to probe magnetic ordering across the Tb Curie temperature as well as magnetic ordering induced by a ferromagnetic substrate in Results are shown for paramagnetic Tb overlayers on Ni(111). The Ginsberg-Landau theory can be used to accurately model terbium thin films for T>Tc.

Go to article

Magnetic And Structural Properties Of High-Coercivity Pr2Fe14Bpr Cosputtered Films, K.D. Aylesworth, David J. Sellmyer, George C. Hadjipanayis May 1990

Magnetic And Structural Properties Of High-Coercivity Pr2Fe14Bpr Cosputtered Films, K.D. Aylesworth, David J. Sellmyer, George C. Hadjipanayis

David Sellmyer Publications

The results of structural and magnetic measurements on a series of films produced by cosputtering Pr21Fe72B7 and Pr are reported. The materials were deposited serially, 10–200 Å at a time, onto 700 °C Ta substrates attached to a computer-controlled stepping motor. The structure of the resulting films was examined by large- and small-angle x-ray diffraction, scanning electron microscopy, and by microprobe analysis. Magnetic measurements were made at temperatures from 4.2 to 300 K, in fields up to 80 kOe in a vibrating sample magnetometer. The films appear to consist of 1-µm grains of Pr2 …

Go to article

Enhancement Of Magneto-Optical Kerr Effects, Liang-Yao Chen, William A. Mcgahan, Z.S. Shan, David J. Sellmyer, John A. Woollam May 1990

Enhancement Of Magneto-Optical Kerr Effects, Liang-Yao Chen, William A. Mcgahan, Z.S. Shan, David J. Sellmyer, John A. Woollam

David Sellmyer Publications

A general expression for the magneto-optical polar Kerr effect is given for a bilayered configuration in which the optical constants of the two media differ. The equation shows that a giant enhancement of the Kerr effect in magneto-optical/metallic bilayers can be expected if the dielectric constants of the two materials are low or are matched well to the other. An explicit equation is also given to calculate the spectral enhancement due to a dielectric overcoating on magnetic substrates. An example is given for SiO-coated Dy/Co compositionally modulated alloys, yielding a good comparison to the experimental results in both the transparent …

Go to article

Magnetic And Structural Studies In Sm-Fe-Ti Magnets, Y. Wang, George C. Hadjipanayis, A. Kim, N.C. Liu, David J. Sellmyer May 1990

Magnetic And Structural Studies In Sm-Fe-Ti Magnets, Y. Wang, George C. Hadjipanayis, A. Kim, N.C. Liu, David J. Sellmyer

David Sellmyer Publications

The effects of vanadium substitution on the magnetic properties of Sm-Fe-Ti-V melt-spun ribbons and the magnetic properties and microstructure of sintered Sm-Fe-Ti based magnets are reported. The highest coercivity, Hc =10.65 kOe, was obtained in a heat-treated melt-spun Sm8 Fe75.5 Ga0.5 Ti8 V8 alloy. This is the highest value of the coercivities reported in alloys with the ThMn12 -type structure. Bulk magnets were prepared by the usual powder metallurgy technique. However, their highest coercivity (~2 kOe) was much less than that of the corresponding ribbons. The low coercivity of sintered magnets has been …

Go to article

Electronic Structure And Magnetic Properties Of Fe-Rich Ternary Compounds: Yfe10V2 And Yfe10Cr2, Sitaram Jaswal, Y.G. Ren, David J. Sellmyer May 1990

Electronic Structure And Magnetic Properties Of Fe-Rich Ternary Compounds: Yfe10V2 And Yfe10Cr2, Sitaram Jaswal, Y.G. Ren, David J. Sellmyer

David Sellmyer Publications

These compounds are prototypes of the Fe-rich ternary systems of ThMn12 structure which are of considerable current interest as permanent magnet materials. The electronic structure of YFe10V2 and YFe10Cr2 have been studied with photoemission and spin-polarized calculations. The Fe d states dominate the calculated density of states (DOS) near the Fermi energy and there is a good correspondence between the DOS and the experimental spectra. The calculated magnetization is in very good agreement with the experimental data. The calculations give a magnetic moment of ~1 µB at the V or Cr site …

Go to article

An Analytic Representation Of The Radial Distribution Of Dose From Energetic Heavy Ions In Water, Si, Lif, Nai, And Sio2, Robert Katz, Kim Sum Loh, Luo Baling, Guo-Rong Huang May 1990

An Analytic Representation Of The Radial Distribution Of Dose From Energetic Heavy Ions In Water, Si, Lif, Nai, And Sio2, Robert Katz, Kim Sum Loh, Luo Baling, Guo-Rong Huang

Robert Katz Publications

An earlier representation of the radial distribution of dose about the path of a heavy ion in liquid water is modified and extended to include silicon, lithium fluoride, sodium iodide, and silicon dioxide.

Go to article

Infrared-Absorption Of Deep Defects In Molecular-Beam-Epitaxial Gaas-Layers Grown At 200°C - Observation Of An El(2)-Like Defect, M. O. Manasreh, David C. Look, K. R. Evans May 1990

Infrared-Absorption Of Deep Defects In Molecular-Beam-Epitaxial Gaas-Layers Grown At 200°C - Observation Of An El(2)-Like Defect, M. O. Manasreh, David C. Look, K. R. Evans

Physics Faculty Publications

Infrared optical absorption and Hall-effect techniques were employed to study deep defects in As-rich molecular-beam-epitaxial GaAs layers grown at very low temperature (200°C). A large ir absorption band was observed between 0.55 eV and the band edge. This band is composed of photoquenchable and photounquenchable components. Photoquenching, thermal recovery from the metastable state, and ir absorption properties of the quenchable defect, of estimated concentration ~3x1018 cm-3, are identical to those of EL2. On the other hand, the unquenchable defect, of estimated concentration ~3x1019 cm-3, resembles the isolated AsGa, antisite observed in …

Go to article

Pair-Correlation Kinetics And The Reversible Diffusion-Controlled Reaction, David Peak, D C. Greenlaw, L A. Schick May 1990

Pair-Correlation Kinetics And The Reversible Diffusion-Controlled Reaction, David Peak, D C. Greenlaw, L A. Schick

All Physics Faculty Publications

It has long been known that the time course of a bimolecular reaction occurring in a condensed host depends on the behavior of the nonequilibrium pair-correlation function for reactant pairs. The classical analysis of such reactions has led to a kind of standard rule: The association rate constant for a diffusion-controlled reaction is 4πDR and this rate constant produces the fastest possible kinetics. This result is only (approximately) true for the case of an irreversible reaction, however. Here, we reexamine this old problem, looking closely at the reversible case. We report a result that challenges the standard wisdom: When the …

Go to article

Rate Equation And Scaling For Fragmentation With Mass Loss, Boyd F. Edwards, M. Cai, H. Han May 1990

Rate Equation And Scaling For Fragmentation With Mass Loss, Boyd F. Edwards, M. Cai, H. Han

All Physics Faculty Publications

A linear rate equation describes fragmentation with continuous and discrete mass loss typified by consumption of porous reactive solids and two-phase heterogeneous solids. For a mass-dependent fragmentation rate xα and a continuous-mass-loss rate εxγ,σ=γ-α-1<0 yields a>‘‘recession regime’’ where small particles lose mass continuously without breaking, σ>0 yields a ‘‘fragmentation regime’’ where all particles break, and σ=0 yields scaling for α>0. Shattering for α<0 and>σ≥0 is runaway fragmentation producing an infinte number of particles in a finite time, Exact and asymptotic solutions, exponent relations, and connections with static percolation are found.

Go to article

Atomistic Mechanisms And Dynamics Of Adhesion, Nanoindentation, And Fracture, Nancy Burnham, Uzi Landman, Wd Luedtke, Richard Colton Apr 1990

Atomistic Mechanisms And Dynamics Of Adhesion, Nanoindentation, And Fracture, Nancy Burnham, Uzi Landman, Wd Luedtke, Richard Colton

Nancy A. Burnham

Molecular dynamics simulations and atomic force microscopy are used to investigate the atomistic mechanisms of adhesion, contact formation, nanoindentation, separation, and fracture that occur when a nickel tip interacts with a gold surface. The theoretically predicted and experimentally measured hysteresis in the force versus tip-to-sample distance relationship, found upon approach and subsequent separation of the tip from the sample, is related to inelastic deformation of the sample surface characterized by adhesion of gold atoms to the nickel tip and formation of a connective neck of atoms. At small tipsample distances, mechanical instability causes the tip and surface to jump-to-contact, which …

Go to article

Probing The Surface Forces Of Monolayer Films With An Atomic-Force Microscope, Nancy Burnham, Dawn Dominguez, Robert Mowery, Richard Colton Apr 1990

Probing The Surface Forces Of Monolayer Films With An Atomic-Force Microscope, Nancy Burnham, Dawn Dominguez, Robert Mowery, Richard Colton

Nancy A. Burnham

Using an atomic force microscope (AFM), we have studied the attractive and adhesive forces between a cantilever tip and sample surfaces as a function of sample surface energy. The measured forces systematically increased with surface energy. The AFM is very sensitive; changes in the surface forces (i.e., attraction and adhesion) of monolayer covered samples could be clearly discerned when only the surface group of the monolayer film was changed from -CH3 to -CF3.

Go to article

Variational Methods For High-Order Multiphoton Processes, Bo Gao, Cheng Pan, Chih-Ray Liu, Anthony F. Starace Apr 1990

Variational Methods For High-Order Multiphoton Processes, Bo Gao, Cheng Pan, Chih-Ray Liu, Anthony F. Starace

Anthony F. Starace Publications

Methods for applying the variationally stable procedure for N th-order perturbative transition matrix elements of Gao and Starace [Phys. Rev. Lett. 61, 404 (1988); Phys. Rev. A 39, 4550 (1989)] to multiphoton processes involving systems other than atomic H are presented. Three specific cases are discussed: one-electron ions or atoms in which the electron-ion interaction is described by a central potential; two-electron ions or atoms in which the electronic states are described by the adiabatic hyperspherical representation; and closed-shell ions or atoms in which the electronic states are described by the multiconfiguration Hartree-Fock representation. Applications are made to the dynamic …

Go to article

Nonlocal Effects In Dissociative Electron Attachment To H2, D E. Atems, J M. Wadehra Apr 1990

Nonlocal Effects In Dissociative Electron Attachment To H2, D E. Atems, J M. Wadehra

Physics and Astronomy Faculty Research Publications

Electron scattering by diatomic molecules involving the formation of a single resonance is treated within the configuration-interaction formalism. A technique is presented for solving the resulting nonlocal integro-differential equation for the nuclear motion in the resonant state. This technique is applied to the scattering of electrons by molecular hydrogen (and its isotopes) via the formation of X^2 Σ^+_u resonance, using a semiempirical model for the resonant state. Numerical cross sections for dissociative attachment, to H_2, of electrons with energies below 5 eV are presented and compared both with available experimental data and with those obtained using the local approximation for …

Go to article

Rovibrationally Enhanced Dissociative Electron Attachment To Molecular Lithium, J M. Wadehra Apr 1990

Rovibrationally Enhanced Dissociative Electron Attachment To Molecular Lithium, J M. Wadehra

Physics and Astronomy Faculty Research Publications

We have investigated the role played by initial rovibrational excitation of Li_2 on the cross sections and rates for dissociative electron attachment to the molecule. For a given internal energy, the vibrational excitation enhances the attachment cross section more than the rotational excitation. The attachment cross sections and the attachment rates reach their maximum values when the process of dissociative attachment to rovibrationally excited molecules is still endoergic and, furthermore, these quantities stay close to their maximum values even when the process changes from being endoergic to exoergic. The upper bounds on the cross sections and the rates for dissociative …

Go to article

First Prev Next Last