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 29551 - 29580 of 36686

Full-Text Articles in Physical Sciences and Mathematics

Radar Studies Of Mid-Latitude Ionospheric Plasma Drifts, L. Scherliess, Bela G. Fejer, J. Holt, L. Goncharenko, C. Armory-Mazaudier, M. J. Buonsanto Feb 2001

Radar Studies Of Mid-Latitude Ionospheric Plasma Drifts, L. Scherliess, Bela G. Fejer, J. Holt, L. Goncharenko, C. Armory-Mazaudier, M. J. Buonsanto

Bela G. Fejer

We use incoherent scatter radar measurements from Millstone Hill and Saint Santin to study the midlatitude F region electrodynamic plasma drifts during geomagnetically quiet and active periods. We present initially a local time, season, and solar flux dependent analytical model of the quiet time zonal and meridional E × B drifts over these stations. We discuss, for the first time, the Saint Santin drift patterns during solar maximum. We have used these quiet time models to extract the geomagnetic perturbation drifts which were modeled as a function of the time history of the auroral electrojet indices. Our results illustrate the …

Go to article

Two-Dimensional Black Holes As Open Strings: A New Realization Of The Ads/Cft Correspondence, Mariano Cadoni, Marco Cavaglia Feb 2001

Two-Dimensional Black Holes As Open Strings: A New Realization Of The Ads/Cft Correspondence, Mariano Cadoni, Marco Cavaglia

Physics Faculty Research & Creative Works

We show that weak-coupled two-dimensional dilation gravity on anti-de Sitter space can be described by the dynamics of an open string. Neumann and Dirichlet boundary conditions for the string lead two different realizations of the anti-de Sitter/Conformal Field Theory correspondence. In particular, in the Dirichlet case the thermodynamical entropy of two-dimensional black holes can be exactly reproduced by counting the string states.

Go to article

A Spectroscopic And Photometric Study Of Short-Timescale Variability In Ngc 5548, M. Dietrich, C. F. Bender, D. J. Bergmann, T. E. Bills, N. G. Bochkarev, A. Burenkov, C. Martin Gaskell, D. D. Gutzmer, R. Grove, M. E. Hiller, J. P. Huchra, Elizabeth S. Klimek, C. Lund, Nelly I. Merkulova, S. Pebley, Matt Poulsen, V. I. Pronik, S. G. Sergeev, E. A. Sergeeva, A. I. Shapovalova, V. V. Vlasyuk, Belinda J. Wilkes Feb 2001

A Spectroscopic And Photometric Study Of Short-Timescale Variability In Ngc 5548, M. Dietrich, C. F. Bender, D. J. Bergmann, T. E. Bills, N. G. Bochkarev, A. Burenkov, C. Martin Gaskell, D. D. Gutzmer, R. Grove, M. E. Hiller, J. P. Huchra, Elizabeth S. Klimek, C. Lund, Nelly I. Merkulova, S. Pebley, Matt Poulsen, V. I. Pronik, S. G. Sergeev, E. A. Sergeeva, A. I. Shapovalova, V. V. Vlasyuk, Belinda J. Wilkes

Department of Physics and Astronomy: Faculty Publications

Results of a ground-based optical monitoring campaign on NGC 5548 in June 1998 are presented. The broad-band fluxes (U, B, V), and the spectrophotometric optical continuum flux Fλ (5100 Å) monotonically decreased in flux while the broad-band R and I fluxes and the integrated emission-line fluxes of Hα and Hβ remained constant to within 5% . On June 22, a short continuum flare was detected in the broad band fluxes. It had an amplitude of about ~18% and it lasted only ≈90 min. The broad band fluxes and the optical continuum Fλ (5100 Å) appear to …

Go to article

Polarization Effects In Quantum Coherences Probed By Two-Color, Resonant Four-Wave Mixing In The Time Domain, Elizabeth Mccormack, E. Sarajlic Feb 2001

Polarization Effects In Quantum Coherences Probed By Two-Color, Resonant Four-Wave Mixing In The Time Domain, Elizabeth Mccormack, E. Sarajlic

Physics Faculty Research and Scholarship

We present a combined theoretical and experimental study of the effects of laser polarization on optical coherences produced in two-color, resonant four-wave mixing (TC-RFWM). A time-dependent model incorporating diagrammatic perturbation theory and spherical tensor formalism is used to interpret observations of quantum beats due to molecular hyperfine structure in time-resolved TC-RFWM in nitric oxide. Good agreement is found between the model and the observed time-resolved signals for two distinct excitation schemes and a variety of polarization configurations including both polarization and population gratings. Measured hyperfine energy intervals are reported for the X(2)Pi (1/2) , v = 0 ground state and …

Go to article

A2bi8se1 3 (A = Rb, Cs), Csbi3.67se6, And Babi2< /Inf>Se4: New Ternary Semiconducting Bismuth Selenides, Lykourgis Iordanidis, Paul Brazis, Theodora Kyratsi, John Irel, Melissa Lane, Carl Kannewurf, Wei Chen, Jeffrey Dyck, Ctirad Uher, Nishant Ghelani, Tim Hogan, Mercouri Kanatzidis Jan 2001

A2bi8se1 3 (A = Rb, Cs), Csbi3.67se6, And Babi2< /Inf>Se4: New Ternary Semiconducting Bismuth Selenides, Lykourgis Iordanidis, Paul Brazis, Theodora Kyratsi, John Irel, Melissa Lane, Carl Kannewurf, Wei Chen, Jeffrey Dyck, Ctirad Uher, Nishant Ghelani, Tim Hogan, Mercouri Kanatzidis

Jeffrey Dyck

No abstract provided.

Go to article

Laser-Triggered Ion Acceleration And Table Top Isotope Production, K. Nemoto, Anatoly Maksimchuk, Sudeep Banerjee, K. Flippo, G. Mourou, Donald P. Umstadter, B. Yu. Bychenkov Jan 2001

Laser-Triggered Ion Acceleration And Table Top Isotope Production, K. Nemoto, Anatoly Maksimchuk, Sudeep Banerjee, K. Flippo, G. Mourou, Donald P. Umstadter, B. Yu. Bychenkov

Donald Umstadter Publications

We have observed deuterons accelerated to energies of about 2 MeV in the interaction of relativistically intense 10 TW, 400 fs laser pulse with a thin layer of deuterated polystyrene deposited on Mylar film. These high-energy deuterons were directed to the boron sample, where they produced ~105 atoms of positron active isotope 11C from the reaction 10B(d,n)11C. The activation results suggest that deuterons were accelerated from the front surface of the target.

Go to article

Potential Phase Control Of Chromium Oxide Thin Films Prepared By Laser-Initiated Organometallic Chemical Vapor Deposition, Ruihua Cheng, C.N. Borca, Peter A. Dowben, Shane Stadler, Y.U. Idzerda Jan 2001

Potential Phase Control Of Chromium Oxide Thin Films Prepared By Laser-Initiated Organometallic Chemical Vapor Deposition, Ruihua Cheng, C.N. Borca, Peter A. Dowben, Shane Stadler, Y.U. Idzerda

Peter Dowben Publications

We have used laser-initiated chemical vapor deposition to grow the chromium oxide thin films through the oxidation of Cr(CO)6 in an oxygen environment. While both Cr2O3 and CrO2 are present in the film, the relative weight of each phase depends on the oxygen partial pressure. The Curie temperature of the film increases and approaches the bulk TC of CrO2 (397 K) as the partial oxygen pressure is increased. © 2001 American Institute of Physics. [DOI: 10.1063/1.1343846]

Go to article

Comparison Of Aluminum And Sodium Doped Poly(Vinylidene Fluoride-Trifluoroethylene) Copolymers By X-Ray Photoemission Spectroscopy, B. Xu, Jaewu Choi, C.N. Borca, Peter A. Dowben, A.V. Sorokin, S.P. Palto, N.N. Petukhova, S.G. Yudin Jan 2001

Comparison Of Aluminum And Sodium Doped Poly(Vinylidene Fluoride-Trifluoroethylene) Copolymers By X-Ray Photoemission Spectroscopy, B. Xu, Jaewu Choi, C.N. Borca, Peter A. Dowben, A.V. Sorokin, S.P. Palto, N.N. Petukhova, S.G. Yudin

Peter Dowben Publications

The chemical interaction between the simple metals, aluminum and sodium, and crystalline copolymer thin films of vinylidene fluoride (70%) with trifluoroethylene (30%), has been studied using x-ray photoemission spectroscopy. Aluminum and sodium metalize the polymer differently and different binding sites for the two metals can be inferred from the corresponding core level shifts. Aluminum leads to enhanced screening of final photoemission states associated with the polymer, while sodium doping strongly influences the fluorine, but perturbs the carbon backbone only slightly. © 2001 American Institute of Physics. [DOI: 10.1063/1.1340858]

Go to article

Aluminum Doping Of Poly(Vinylidene Fluoride With Trifluoroethylene) Copolymer, B. Xu, C.N. Borca, Stephen Ducharme, A.V. Sorokin, Peter A. Dowben, V.M. Fridkin, S.P. Palto, N.N. Petukhova, S.G. Yudin Jan 2001

Aluminum Doping Of Poly(Vinylidene Fluoride With Trifluoroethylene) Copolymer, B. Xu, C.N. Borca, Stephen Ducharme, A.V. Sorokin, Peter A. Dowben, V.M. Fridkin, S.P. Palto, N.N. Petukhova, S.G. Yudin

Peter Dowben Publications

The interface between aluminum and crystalline copolymer thin film of vinylidene fluoride (70%) with trifluoroethylene (30%) [PVDF-TrFE] has been studied. The ratio of carbon 1s and aluminum 2p core level photoemission peak intensities changes little with increasing emission angle after deposition of 5 Å aluminum on the surface of PVDF-TrFE. This indicates that the distribution of aluminum atoms in the copolymer film is quite uniform in the near surface region and that the interface between PVDF-TrFE and aluminum is not abrupt. There is evidence for changes in photohole screening with aluminum doping within the polymer film.

Go to article

Aluminum Doping Of Poly„Vinylidene Fluoride, B. Xu, C.N. Borca, Stephen Ducharme, A.V. Sorokin, Peter A. Dowben, V.M. Fridkin, S.P. Palto, N.N. Petukhova, S.G. Yudin Jan 2001

Aluminum Doping Of Poly„Vinylidene Fluoride, B. Xu, C.N. Borca, Stephen Ducharme, A.V. Sorokin, Peter A. Dowben, V.M. Fridkin, S.P. Palto, N.N. Petukhova, S.G. Yudin

Stephen Ducharme Publications

The interface between aluminum and crystalline copolymer thin film of vinylidene fluoride (70%) with trifluoroethylene (30%) [PVDF-TrFE] has been studied. The ratio of carbon 1s and aluminum 2p core level photoemission peak intensities changes little with increasing emission angle after deposition of 5 Å aluminum on the surface of PVDF-TrFE. This indicates that the distribution of aluminum atoms in the copolymer film is quite uniform in the near surface region and that the interface between PVDF-TrFE and aluminum is not abrupt. There is evidence for changes in photohole screening with aluminum doping within the polymer film.

Go to article

Sige/Si Thz Laser Based On Transitions Between Inverted Mass Light-Hole And Heavy-Hole Subbands, L. Friedman, Greg Sun, Richard A. Soref Jan 2001

Sige/Si Thz Laser Based On Transitions Between Inverted Mass Light-Hole And Heavy-Hole Subbands, L. Friedman, Greg Sun, Richard A. Soref

Physics Faculty Publications

We have investigated a SiGe/Si quantum-well laser based on transitions between the light-hole and heavy-hole subbands. The lasing occurs in the region of k space where the dispersion of ground-state light-hole subband is so nonparabolic that its effective mass is inverted. This kind of lasing mechanism makes total population inversion between the two subbands unnecessary. The laser structure can be electrically pumped through tunneling in a quantum cascade scheme. Optical gain as high as 172/cm at the wavelength of 50 μm can be achieved at the temperature of liquid nitrogen, even when the population of the upper laser subband is …

Go to article

Quasistationary Stabilization Of The Decay Of A Weakly-Bound Level And Its Breakdown In A Strong Laser Field, N. L. Manakov, M. V. Frolov, Bogdan Borca, Anthony F. Starace Jan 2001

Quasistationary Stabilization Of The Decay Of A Weakly-Bound Level And Its Breakdown In A Strong Laser Field, N. L. Manakov, M. V. Frolov, Bogdan Borca, Anthony F. Starace

Anthony F. Starace Publications

Although it was pointed out about 10 years ago that an atomic decay rate might decrease as the intensity of a high-frequency laser field increases, there still does not exist any complete understanding of either the physical origin of this interesting nonlinear phenomenon or its dependence on the atomic and field parameters. Essentially, the problem consists in that the phenomenon requires a major modification of the standard picture of photoeffect in a strong laser field. In Reference #1 the origin of this stabilization is related to a particular distortion of an atomic potential by an intense monochromatic high-frequency field. This …

Go to article

Anisotropy-Induced Polarization Effects In Harmonic Generation By An Absorptive Medium, Bogdan Borca, D. B. Milosević, Anthony F. Starace, A. V. Flegel, M. V. Frolov, N. L. Manakov Jan 2001

Anisotropy-Induced Polarization Effects In Harmonic Generation By An Absorptive Medium, Bogdan Borca, D. B. Milosević, Anthony F. Starace, A. V. Flegel, M. V. Frolov, N. L. Manakov

Anthony F. Starace Publications

High-order harmonic generation (HHG) has become a main topic of intense laser-atom physics. Both to understand the HHG process better and to enhance its use in applications, many studies have focused on the control of HHG. Among the most recent are those concerned with the polarization characteristics of the harmonics. Other studies have focused on the use of a strong static electric field to control the intensities and plateau structure of HHG. In this paper we present results of a general formulation of the problem of HHG in the case when the generating medium is anisotropic. Our specific results are …

Go to article

Simple Relationships For The Estimation Of Melting Temperatures Of Homologous Series, James S. Chickos, Gary Nichols Jan 2001

Simple Relationships For The Estimation Of Melting Temperatures Of Homologous Series, James S. Chickos, Gary Nichols

James Chickos

No abstract provided.

Go to article

Reply To “Comment On ‘Photodetachment In Combined Static And Dynamic Electric Fields’”, A. R. P. Rau, Chitra Rangan Jan 2001

Reply To “Comment On ‘Photodetachment In Combined Static And Dynamic Electric Fields’”, A. R. P. Rau, Chitra Rangan

Physics Publications

While distortion of the initial negative-ion state by a strong static electric field can have observable effects, the effect attributed by the authors of the preceding Comment [Phys. Rev. A 64, 037401 (2001)] to a cross term between the detaching laser field and the static field is spurious, an artifact of their procedures. Other points of dispute are also clarified.

Go to article

Optimally Shaped Terahertz Pulses For Phase Retrieval In A Rydberg-Atom Data Register, Chitra Rangan, P.H. Bucksbaum Jan 2001

Optimally Shaped Terahertz Pulses For Phase Retrieval In A Rydberg-Atom Data Register, Chitra Rangan, P.H. Bucksbaum

Physics Publications

A terahertz pulse was designed to implement a search algorithm on a quantum data register. Phase information stored in a Rydberg wave packet was optimally retrieved through the interaction with the pulse. Careful attention was paid to the smooth switch on and switch off of the terahertz pulse. Furthermore, the possibility of designing an optimal pulse that can achieve not only a desired target state of an atom, but also implement a desired algorithm was shown.

Go to article

Quantum Phase Retrieval Of A Rydberg Wave Packet Using A Half-Cycle Pulse, J. Ahn, D.N. Hutchinson, Chitra Rangan, P.H. Bucksbaum Jan 2001

Quantum Phase Retrieval Of A Rydberg Wave Packet Using A Half-Cycle Pulse, J. Ahn, D.N. Hutchinson, Chitra Rangan, P.H. Bucksbaum

Physics Publications

The half-cycle pulse (HCP) was used to search for information stored as phase in a Rydberg wave packet. Phase information coded in a Rydberg quantum register was retrieved through the impulsive interaction of HCP. In general, results of the study point to the use of HCPs as general tools for analysis for unknown wave packet.

Go to article

Measurement Of The Hyperfine Structure Of The 4d2d 3/2,5/2 Levels And Isotope Shifts Of The 4p2p 3/2 ? 4d2d3/2 And 4p2p 3/2 ? 4d2d5/2 Transitions In Gallium 69 And 71, Steven J. Rehse, W.M. Fairbank Jr., S.A. Lee Jan 2001

Measurement Of The Hyperfine Structure Of The 4d2d 3/2,5/2 Levels And Isotope Shifts Of The 4p2p 3/2 ? 4d2d3/2 And 4p2p 3/2 ? 4d2d5/2 Transitions In Gallium 69 And 71, Steven J. Rehse, W.M. Fairbank Jr., S.A. Lee

Physics Publications

The hyperfine structure of the 4d2D3/2,5/2 levels of 69,71Ga is determined. The 4p2P3/2 ? 4d2D3/2 (294.50-nm) and 4p2P3/2 ? 4d2D5/2 (294.45-nm) transitions are studied by laser-induced fluorescence in an atomic Ga beam. The hyperfine A constant measured for the 4d2D5/2 level is 77.3 ± 0.9 MHz for 69Ga and 97.9 ± 0.7 MHz for 71Ga (3s errors). The A constant measured for the 4d2D3/2 level is -36.3 ± 2.2 MHz for 69Ga and -46.2 ± 3.8 MHz for 71Ga. These measurements correct sign errors in the previous determination of these constants. For 69Ga the hyperfine B constants measured for the …

Go to article

Lamb Shift In He+: Resolution Of A Discrepancy Between Theory And Experiment, A. Van Wijngaarden, F. Holuj, Gordon W. F. Drake Jan 2001

Lamb Shift In He+: Resolution Of A Discrepancy Between Theory And Experiment, A. Van Wijngaarden, F. Holuj, Gordon W. F. Drake

Physics Publications

The Lamb shift in helium ions were investigated to verify or remove a discrepancy between theory and experiment by the anisotropy method. The method was used for the elimination of residual polarization sensitivity of the photon detectors. The results showed that the experimental value of a Lamb shift were in agreement with the theoretical values.

Go to article

Intermediate Spin, Schrödinger Cat States, And Nanomagnets, S. E. Barnes Jan 2001

Intermediate Spin, Schrödinger Cat States, And Nanomagnets, S. E. Barnes

Physics Articles and Papers

Quantum tunneling in nanomagnets finds a natural description in terms of intermediate spin. Periodic magnetic effects correspond to a change of flux by the flux quantum Φ0. Schrödinger cat states with different superpositions of the applied magnetic field occur. The molecular magnet Fe8 is discussed and new effects are predicted for Mn12.

Go to article

Multilayer Mim Inversion Of Aem Data: Theory And Field Example, Clyde J. Bergeron Jr, Juliette W. Ioup, Yan Wu, George E. Ioup, Kenneth W. Holladay Jan 2001

Multilayer Mim Inversion Of Aem Data: Theory And Field Example, Clyde J. Bergeron Jr, Juliette W. Ioup, Yan Wu, George E. Ioup, Kenneth W. Holladay

Physics Faculty Publications

This paper presents a multilayer generalization of an algebraic method of inverting frequency-doma in airborne active electromagnetic (AEM) data in terms of 1-D layered earth models. The processing of the AEM data, which includes a recalibration procedure, is also outlined. The inversion is applied to synthetic fields generated from a multilayer model which is intended to approximate a measured conductivity profile of the water column in the Gulf of Mexico and to measured AEM data from a survey of the Barataria Bay estuary region of the Louisiana Gulf of Mexico coast. The inversion results from the synthetic data are in …

Go to article

Energy Localization Invariance Of Tidal Work In General Relativity, Marc Favata Jan 2001

Energy Localization Invariance Of Tidal Work In General Relativity, Marc Favata

Department of Physics and Astronomy Faculty Scholarship and Creative Works

It is well known that when an external general relativistic (electric-type) tidal field (Formula presented) interacts with the evolving quadrupole moment (Formula presented) of an isolated body the tidal field does work on the body (“tidal work”)—i.e., it transfers energy to the body—at a rate given by the same formula as in Newtonian theory: (Formula presented) Thorne has posed the following question: In view of the fact that the gravitational interaction energy (Formula presented) between the tidal field and the body is ambiguous by an amount (Formula presented) is the tidal work also ambiguous by this amount, and therefore is …

Go to article

Reactivity And Electronic Structure Of Aluminum Clusters: The Aluminum-Nitrogen System, B. D. Leskiw, A. W. Castleman Jr., C. Ashman, S. N. Khanna Jan 2001

Reactivity And Electronic Structure Of Aluminum Clusters: The Aluminum-Nitrogen System, B. D. Leskiw, A. W. Castleman Jr., C. Ashman, S. N. Khanna

Physics Publications

The stability of anionic aluminum–nitrogen clusters has been examined and Al2N−, Al3N−2,Al5N−2, Al6N−3, Al8N−3, and Al9N−2 are found to be particularly stable. Theoreticaldensity functional calculations on neutral and anionic AlnN (n=1–8) clusters were performed and the stability and reaction energetics with oxygen examined. Clusters requiring less than 5.7 eV to remove an electron and an Al atom are shown to be resistant to the reaction with oxygen.

Go to article

Geometry, Electronic Structure, And Energetics Of Copper-Doped Aluminum Clusters, S. N. Khanna, C. Ashman, B. K. Rao, P. Jena Jan 2001

Geometry, Electronic Structure, And Energetics Of Copper-Doped Aluminum Clusters, S. N. Khanna, C. Ashman, B. K. Rao, P. Jena

Physics Publications

Using density functional theory and generalized gradient approximation for exchange-correlation potential, we have calculated the equilibrium geometries and energetics of neutral and negatively charged AlnCu (n=11,12,13,14) clusters. Unlike the alkali atom-doped aluminum clusters in the same size range, the copper atom resides inside the aluminum cluster cage. Furthermore, the 3d and 4s energy levels of Cu hybridize with the valence electrons of Al causing a redistribution of the molecular orbital energy levels of the Aln clusters. However, this redistribution does not affect the magic numbers of AlnCu clusters that could be derived by assuming that Cu donates one electron to …

Go to article

Electronic Structure And Chemical Bonding Of 3d-Metal Dimers Scx, X=Sc-Zn, G. L. Gutsev, P. Jena, B. K. Rao, S. N. Khanna Jan 2001

Electronic Structure And Chemical Bonding Of 3d-Metal Dimers Scx, X=Sc-Zn, G. L. Gutsev, P. Jena, B. K. Rao, S. N. Khanna

Physics Publications

The electronic and geometrical structures of the ground and excited states of the homonuclear Sc2, mixed ScTi, ScV, ScCr, ScMn, ScFe, ScCo, ScNi, ScCu, and ScZn 3d-metal dimers and their anions have been calculated using the density functional theory with generalized gradient approximation for the exchange-correlation potential. The ground states of the neutral dimers are found to be 5Σ−u (Sc2), 6Σ+ (ScTi), 7Σ+ (ScV), 4Σ+ (ScCr), 3Σ+ (ScMn), 2Δ(ScFe), 1Σ+ (ScCo), 2Σ+ (ScNi), 3Δ(ScCu), and 4Σ+ (ScZn). A natural bond analysis reveals an antiferrimagnetic spin coupling in the ground states of ScCr, ScMn, and ScFe. This is due to the …

Go to article

Energetics And Electronic Structure Of Carbon Doped Aluminum Clusters, B. K. Rao, P. Jena Jan 2001

Energetics And Electronic Structure Of Carbon Doped Aluminum Clusters, B. K. Rao, P. Jena

Physics Publications

The energetics and the electronic structure of AlnC clusters (n=3, 4, 5; 11, 12, 13) have been studied by a global optimization of their geometry without any symmetry constraint. The total energies of these clusters both in neutral and charged states are calculated using an all-electron basis and the generalized gradient approximation to the density functional theory. While Al4C and Al12C clusters share some characteristic features of closed shell structures, namely enhanced stability and low electron affinity compared to their neighboring sizes, their ionization potentials exhibit different behavior. These decrease steadily from Al3C to Al5C while that of Al12C is …

Go to article

Electronic Structure Of Chromium Oxides, Cron- And Cron (N=1-5) From Photoelectron Spectroscopy And Density Functional Theory Calculations, G. L. Gutsev, P. Jena, Hua-Jin Zhai, Lai-Sheng Wang Jan 2001

Electronic Structure Of Chromium Oxides, Cron- And Cron (N=1-5) From Photoelectron Spectroscopy And Density Functional Theory Calculations, G. L. Gutsev, P. Jena, Hua-Jin Zhai, Lai-Sheng Wang

Physics Publications

The electronic structure of CrO−n and CrOn (n=1–5) was investigated using anion photoelectron spectroscopy and density functional theory. Photoelectron spectra of CrO−n were obtained at several photon energies and yielded electron affinities, vibrational and electronic structure information about the neutral CrOn species. Density functional theory calculations were carried out for both the neutrals and anions and were used to interpret the experimental spectra. Several low-lying electronic states of CrO were observed and assigned from photodetachment of the CrO− ground state(6∑+) and an excited state (4∏), which is only 0.1 eV higher. The main spectral features of CrO−2 were interpreted based …

Go to article

Orientation And Speed Of The Parsec-Scale Jet In Ngc4261 (3c270), B. Glenn Piner, Dayton L. Jones, Ann E. Wehrle Jan 2001

Orientation And Speed Of The Parsec-Scale Jet In Ngc4261 (3c270), B. Glenn Piner, Dayton L. Jones, Ann E. Wehrle

Physics

NGC 4261 (3C 270) is an elliptical galaxy containing a 300 pc–scale nuclear disk of gas and dust imaged by the Hubble Space Telescope (HST), around a central supermassive black hole. Previous VLBI observations of NGC 4261 revealed a gap in emission in the radio counterjet, presumably due to free-free absorption in the inner parsec of the accretion disk. Here we present three 8 GHz VLBA observations of NGC 4261 that allow us to monitor the location and depth of the gap and check for motions in the jet and counterjet. The separation between the brightest peak and …

Go to article

Coptcr:C Nanocomposite Films For High Density Recording, H. Zeng, M.L. Yan, Yi Liu, David J. Sellmyer Jan 2001

Coptcr:C Nanocomposite Films For High Density Recording, H. Zeng, M.L. Yan, Yi Liu, David J. Sellmyer

David Sellmyer Publications

We report results on the magnetic properties of nanocomposite films of the form (Co86Cr14)xPt1-x:C, which were prepared by magnetron sputtering and subsequent annealing. X-ray diffraction shows that these films consist of CoPtCr grains with the face-centered-tetragonal structure embedded in an amorphous C matrix. Magnetic properties such as coercivity (Hc), remanence ratio (S), and coercive squareness (S*) are strongly dependent on the Pt and C composition and annealing temperatures. Compared with previously reported CoPt:C films with a equiatomic Co and Pt ratio, lower exchange coupling and …

Go to article

Measurement Of Dσ/Dy For High Mass Drell-Yan E+E- Pairs From Pp̅ Collisions At √S =1.8 Tev, T. Affolder, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration Jan 2001

Measurement Of Dσ/Dy For High Mass Drell-Yan E+E- Pairs From Pp̅ Collisions At √S =1.8 Tev, T. Affolder, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration

Kenneth Bloom Publications

No abstract provided.

Go to article

First Prev Next Last