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Ratios Of Multijet Cross Sections In Pp̅ Collisions At √S = 1.8 Tev, B. Abbott, Gregory R. Snow, D0 Collaboration Mar 2001

Ratios Of Multijet Cross Sections In Pp̅ Collisions At √S = 1.8 Tev, B. Abbott, Gregory R. Snow, D0 Collaboration

Gregory Snow Publications

We report on a study of the ratio of inclusive three-jet to inclusive two-jet production cross sections as a function of total transverse energy in pp̅ collisions at a center-of-mass energy√s = 1.8 TeV, using data collected with the D0 detector during the 1992–1993 run of the Fermilab Tevatron Collider. The measurements are used to deduce preferred renormalization scales in perturbative O(αs3) QCD calculations in modeling soft-jet emission.

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Measurement Of The Angular Distribution Of Electrons From W→Eν Decays Observed In Pp̅ Collisions At √S =1.8 Tev, B. Abbott, Gregory R. Snow, D0 Collaboration Mar 2001

Measurement Of The Angular Distribution Of Electrons From W→Eν Decays Observed In Pp̅ Collisions At √S =1.8 Tev, B. Abbott, Gregory R. Snow, D0 Collaboration

Gregory Snow Publications

We present the first measurement of the electron angular distribution parameter α2 in W→eν events produced in proton-antiproton collisions as a function of the W boson transverse momentum. Our analysis is based on data collected using the DØ detector during the 1994–1995 Fermilab Tevatron run. We compare our results with next-to-leading order perturbative QCD, which predicts an angular distribution of (1 ± α1cos θ*+ α2 cos2 θ*), where θ* is the polar angle of the electron in the Collins-Soper frame. In the presence of QCD corrections, the parameters a1 and a2 become functions of …

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Effects Of Relativity On The Time-Resolved Tunneling Of Electron Wave Packets, P Krekora, Q Su, Rainer Grobe Mar 2001

Effects Of Relativity On The Time-Resolved Tunneling Of Electron Wave Packets, P Krekora, Q Su, Rainer Grobe

Faculty publications – Physics

We solve numerically the time-dependent Dirac equation for a quantum wave packet tunneling through a potential barrier. We analyze the spatial probability distribution of the transmitted wave packet in the context of the possibility of effectively superluminal peak and front velocities of the electron during tunneling. Both the Dirac and Schrodinger theories predict superluminal tunneling speeds. However, in contrast to the Dirac theory the Schrodinger equation allows a possible violation of causality. Based on an analysis of the tunneling process in full temporal and spatial resolution, we introduce an instantaneous tunneling speed that can be computed inside the potential barrier.

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Critical Wavelength For River Meandering, Boyd F. Edwards, D. H. Smith Mar 2001

Critical Wavelength For River Meandering, Boyd F. Edwards, D. H. Smith

All Physics Faculty Publications

A fully nonlinear modal analysis identifies a critical centerline wave number qc for river meandering that separates long-wavelength bends, which grow to cutoff, from short-wavelength bends, which decay. Exact, numerical, and approximate analytical results for qc rely on the Ikeda, Parker, and Sawai [J. Fluid Mech. 112, 363 (1981)] model, supplemented by dynamical equations that govern the river migration and length. Predictions also include upvalley bend migration at long times and a peak in lateral migration rates at intermediate times. Experimental tests are suggested.

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Fractal Quasar Clouds, Mark Bottorff, Gary J. Ferland Mar 2001

Fractal Quasar Clouds, Mark Bottorff, Gary J. Ferland

Physics and Astronomy Faculty Publications

This paper examines whether a fractal cloud geometry can reproduce the emission-line spectra of active galactic nuclei (AGNs). The nature of the emitting clouds is unknown, but many current models invoke various types of magnetohydrodynamic confinement. Recent studies have argued that a fractal distribution of clouds, in which subsets of clouds occur in self-similar hierarchies, is a consequence of such confinement. Whatever the confinement mechanism, fractal cloud geometries are found in nature and may be present in AGNs too. We first outline how a fractal geometry can apply at the center of a luminous quasar. Scaling laws are derived that …

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High Mobility In N-Type Gan Substrates, A. Saxler, David C. Look, S. Elhamri, J. R. Sizelove, William C. Mitchel, C. M. Sung, S. S. Park, K. Y. Lee Mar 2001

High Mobility In N-Type Gan Substrates, A. Saxler, David C. Look, S. Elhamri, J. R. Sizelove, William C. Mitchel, C. M. Sung, S. S. Park, K. Y. Lee

Physics Faculty Publications

No abstract provided.

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Spectral And Temporal Characterization Of High Temperature Events, William F. Bagby Mar 2001

Spectral And Temporal Characterization Of High Temperature Events, William F. Bagby

Theses and Dissertations

The remote observations of the temporal and spectral characteristics of the infrared (IR) emissions from exploding ordnance have been correlated with explosion conditions. A Bomem MR-154 Fourier Transform Interferometer with two detectors, InSb and HgCdTe, was used to record spectra in the 1.3 - 20 micrometers range. Data was collected at spectral resolutions of 16/cm and 4/cm, and temporal resolutions of 0.045 sand 0.123 5, respectively. The data files range in size from 900 Kilobytes to several Megabytes. These are reduced to 2-dimensional representations of temporal features that are less than 100 Kilobytes. The data analysis indicates the possibility of …

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Photoluminescence Of Single Quantum Well Structures In Gallium Arsenide, Christian A. Bartholomew Mar 2001

Photoluminescence Of Single Quantum Well Structures In Gallium Arsenide, Christian A. Bartholomew

Theses and Dissertations

The continued development of state-of the-art semiconductor technologies and devices by the United States Air Force and the Department of Defense requires accurate and efficient techniques to evaluate and model these new materials. Of particular interest to the Air Force are quantum well structures which can be used for small-scale laser sources in fly-by-light applications, as efficient infrared countermeasures to heat-seeking missiles, or as advanced seekers in optically guided missiles. This thesis provides the initial experimental procedures and data necessary to begin producing accurate yet robust models. Although carrier effective masses could not be evaluated using hot-electron photoluminescence, photoluminescence excitation …

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Numerical Study Of Optical Delay In Semiconductor Multilayer Distributed Bragg Reflector And Tunable Microcavity Structures, Michael I. K. Etan Mar 2001

Numerical Study Of Optical Delay In Semiconductor Multilayer Distributed Bragg Reflector And Tunable Microcavity Structures, Michael I. K. Etan

Theses and Dissertations

The Air Force has a growing need for the greater bandwidth, speed, and flexibility offered by optical communication links. Future space systems and airborne platforms will most likely use optical signals for efficient power transmission and to minimize the possibility of spoofing and eavesdropping. Tunable optical delays play an important role in the implementation of free space optical communication links. The primary challenge in implementing these systems is the active maintenance of coherent wave fronts across the system's optical aperture. For space applications, this aperture may he hundreds of meters in diameter. Spatial segmentation of a large aperture into smaller …

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Use Of Quantum Mechanical Calculations To Investigate Small Silicon Carbide Clusters, Jean W. Henry Mar 2001

Use Of Quantum Mechanical Calculations To Investigate Small Silicon Carbide Clusters, Jean W. Henry

Theses and Dissertations

Density Functional Theory (DFT) method was employed to model silicon carbide small clusters. Comparing the DFT calculation results with experimental results that observed by using photoelectron spectroscopy (PES), DFT predicts the same structures that experiment observed. For electron affinity, DFT results are in good agreement with experimental results, the root mean square negative offset 0.1 eV found using medium size of basis set (cc-pVDZ+) calculation. DFT results for vibrational frequencies are in good agreement with experiment results; the root mean square error is 72.5 cm-1 wave number. 16 ground state structures of SimCn (m ≤ 4, …

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Control And Characterization Of Line-Addressable Micromirror Arrays, Harris J. Hall Mar 2001

Control And Characterization Of Line-Addressable Micromirror Arrays, Harris J. Hall

Theses and Dissertations

This research involved the design and implementation of a complete line-addressable control system for a 32x32 electrostatic piston-actuated micromirror array device. Line addressing reduces the number of control lines from N2 to 2N making it possible to design larger arrays and arrays with smaller element sizes. The system utilizes the electromechanical bi-stability of individual elements to bold arbitrary bi-stable phase patterns. The control system applies pulse width modulated (PWM) signals to the rows and columns of the micromirror array. Three modes of operation were conceived and built into the system. The first was the traditional signal scheme which requires …

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Attenuation And Refraction Of An Electromagnetic Wave In An Electron Beam Generated Plasma, Nathaniel P. Lockwood Mar 2001

Attenuation And Refraction Of An Electromagnetic Wave In An Electron Beam Generated Plasma, Nathaniel P. Lockwood

Theses and Dissertations

Artificially generated plasmas may be employed to alter the propagation characteristics of electromagnetic waves. The purpose of this report is to study the propagation of electromagnetic waves in an electron beam generated plasma. To understand the physics related to this concept requires the development of computational tools dealing with a plasma created by an electron beam, an assessment of the temporal and spatial evolution of the plasma, and a characterization of the refraction and attenuation of electromagnetic (EM) waves in a collisional plasma. Three computer programs were developed to characterize the effectiveness of an electron beam generated plasma in refracting …

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Open Strings, 2d Gravity, And Ads/Cft Correspondence, Mariano Cadoni, Marco Cavaglia Mar 2001

Open Strings, 2d Gravity, And Ads/Cft Correspondence, Mariano Cadoni, Marco Cavaglia

Physics Faculty Research & Creative Works

We present a detailed discussion of the duality between dilaton gravity on AdS2 and open strings. The correspondence between the two theories is established using their symmetries and field theoretical, thermodynamic, and statistical arguments. We use the dual conformai field theory to describe two-dimensional black holes. In particular, all the semiclassical features of the black holes, including the entropy, have a natural interpretation in terms of the dual microscopic conformai dynamics. The previous results are discussed in the general framework of the anti-de Sitter/conformal field theory dualities.

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Non-Sequential Double Ionization Of Ne In Intense Laser Pulses: A Coincidence Experiment, Robert Moshammer, Bernold Feuerstein, Daniel Fischer, Alexander Dorn, Claus Dieter Schroter, J. Deipenwisch, Jose R. Crespo Lopez-Urrutia, C. Hohr, Paul B. Neumayer, Joachim Hermann Ullrich, Horst Rottke, Christoph Trump, M. Wittmann, Georg Korn, Wolfgang Sandner Mar 2001

Non-Sequential Double Ionization Of Ne In Intense Laser Pulses: A Coincidence Experiment, Robert Moshammer, Bernold Feuerstein, Daniel Fischer, Alexander Dorn, Claus Dieter Schroter, J. Deipenwisch, Jose R. Crespo Lopez-Urrutia, C. Hohr, Paul B. Neumayer, Joachim Hermann Ullrich, Horst Rottke, Christoph Trump, M. Wittmann, Georg Korn, Wolfgang Sandner

Physics Faculty Research & Creative Works

The dynamics of Neon double ionization by 25 fs, 1.0 PW/cm2 laser pulses at 795 nm has been studied in a many particle coincidence experiment. The momentum vectors of all ejected atomic fragments (electrons and ions) have been measured using combined electron and recoil-ion momentum spectroscopy. Electron emission spectra for double and single ionization will be discussed. In both processes the mean electron energies differ considerably and high energetic electrons with energies of more than 120 eV have been observed for double ionization. The experimental results are in qualitative agreement with the rescattering model.

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Interplay Between Plasmons And The Band Structure For The Mo(112) Surface, I. N. Yakovkin, Jiandi Zhang, Peter A. Dowben Feb 2001

Interplay Between Plasmons And The Band Structure For The Mo(112) Surface, I. N. Yakovkin, Jiandi Zhang, Peter A. Dowben

Peter Dowben Publications

Recent photoemission and inverse photoemission results for the Mo(112) surface are discussed in the framework of the calculated band structure. For the Mo(112) surface, the main photoemission features combine contributions from both the surface and the bulk. Except for those photon energies near to excitations of the bulk and multipole surface plasmons, the comparison of the bulk band structure, along the k points normal to the surface, shows a good agreement with photoemission spectra in the position of the critical points. The dominant surface states at Г̅̅̅ are found to have the a1 symmetry, while the band along Г̅̅̅ …

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Inclusive Jet Production In Pp̅ Collisions, B. Abbott Feb 2001

Inclusive Jet Production In Pp̅ Collisions, B. Abbott

Gregory Snow Publications

We report a new measurement of the pseudorapidity (η) and transverse-energy (ET) dependence of the inclusive jet production cross section in pp̅ collisions at √s = TeV using 95 pb-1 of data collected with the D0 detector at the Fermilab Tevatron. The differential cross section d2σ/(dErdη) is presented up to |η| = 3, significantly extending previous measurements. The results are in good overall agreement with next-to-leading order predictions from QCD and indicate a preference for certain parton distribution functions.

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Measurement Of Dijet Cross Sections For Events With A Leading Neutron In Photoproduction At Hera, J. Breitweg, S. Chekanov, M. Derrick, D. Krakauer, S. Magill, B. Musgrave, A. Pellegrino, J. Repond, R. Stanek, R. Yoshida, Margarita C. K. Mattingly, P. Antonioli, G. Bari, M. Basile, L. Bellagamba, D. Boscherini, A. Bruni, G. Bruni, G. Cara Romeo, L. Cifarelli, F. Cindolo, A. Contin, M. Corradi, S. De Pasquale, P. Giusti, G. Iacobucci, G. Levi, A. Margotti, T. Massam, R. Nania, F. Palmonari Feb 2001

Measurement Of Dijet Cross Sections For Events With A Leading Neutron In Photoproduction At Hera, J. Breitweg, S. Chekanov, M. Derrick, D. Krakauer, S. Magill, B. Musgrave, A. Pellegrino, J. Repond, R. Stanek, R. Yoshida, Margarita C. K. Mattingly, P. Antonioli, G. Bari, M. Basile, L. Bellagamba, D. Boscherini, A. Bruni, G. Bruni, G. Cara Romeo, L. Cifarelli, F. Cindolo, A. Contin, M. Corradi, S. De Pasquale, P. Giusti, G. Iacobucci, G. Levi, A. Margotti, T. Massam, R. Nania, F. Palmonari

Faculty Publications

Differential cross sections for dijet photoproduction in association with a leading neutron using the reaction e+ + p → e+ + n + jet + jet + Xr have been measured with the ZEUS detector at HERA using an integrated luminosity of 6.4 pb-1. The fraction of dijet events with a leading neutron in the final state was studied as a function of the jet kinematic variables. The cross sections were measured for jet transverse energies EjetT > 6 GeV, neutron energy En > 400 GeV, and neutron production angle θn < 0.8 mrad. The data are broadly consistent with factorization of the lepton and hadron vertices and with a simple one-pion-exchange model. © 2001 Elsevier Science B.V. All rights reserved.

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Neutrino Reactions On The Deuteron, S. Nakamura, T. Sato, Vladimir Gudkov, K. Kubodera Feb 2001

Neutrino Reactions On The Deuteron, S. Nakamura, T. Sato, Vladimir Gudkov, K. Kubodera

Faculty Publications

The cross sections for the ν-d and ν̅ -d reactions are calculated for incident energy up to Eν=170 MeV with the use of a phenomenological Lagrangian approach. We assess and improve the reliability of the employed calculational method by examining the dependence of the results on various input and approximations that go into the calculation. The main points of improvement over the existing work are (1) use of the “modern” NN potentials, (2) use of the more accurate nucleon weak-interaction form factors, and (3) monitoring the strength of a vertex that governs the exchange-current contribution, with the use …

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Diamagnetic Persistent Current In Diffusive Normal-Metal Rings, E. M.Q. Jariwala, P. Mohanty, M. B. Ketchen, Richard A. Webb Feb 2001

Diamagnetic Persistent Current In Diffusive Normal-Metal Rings, E. M.Q. Jariwala, P. Mohanty, M. B. Ketchen, Richard A. Webb

Faculty Publications

We have measured a diamagnetic persistent current with flux periodicities of both h/e and h/2e in an array of thirty diffusive mesoscopic gold rings. At the lowest temperatures, the magnitudes of the currents per ring corresponding to the h/e- and h/2e-periodic responses are both comparable to the Thouless energy Ec≡ħ/τD, where τD is the diffusion time. Taken in conjunction with earlier experiments, our results strongly challenge the conventional theories of persistent current. We consider a new approach associated with the saturation of …

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Search For Large Extra Dimensions In Dielectron And Diphoton Production, B. Abbott, Gregory R. Snow, D0 Collaboration Feb 2001

Search For Large Extra Dimensions In Dielectron And Diphoton Production, B. Abbott, Gregory R. Snow, D0 Collaboration

Gregory Snow Publications

We report a search for effects of large extra spatial dimensions in pp̅ collisions at a center-of-mass energy of 1.8 TeV with the D0 detector, using events containing a pair of electrons or photons. The data are in good agreement with the expected background and do not exhibit evidence for large extra dimensions. We set the most restrictive lower limits to date, at the 95% C.L. on the effective Planck scale between 1.0 and 1.4 TeV for several formalisms and numbers of extra dimensions.

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Charge Exchange Contribution To The Decay Of The Ring Current, Measured By Energetic Neutral Atoms (Enas), A. M. Jorgensen, M. G. Henderson, E. C. Roelof, G. D. Reeves, Harlan E. Spence Feb 2001

Charge Exchange Contribution To The Decay Of The Ring Current, Measured By Energetic Neutral Atoms (Enas), A. M. Jorgensen, M. G. Henderson, E. C. Roelof, G. D. Reeves, Harlan E. Spence

Physics & Astronomy

In this paper we calculate the contribution of charge exchange to the decay of the ring current. Past works have suggested that charge exchange of ring current protons is primarily responsible for the decay of the ring current during the late recovery phase, but there is still much debate about the fast decay of the early recovery phase. We use energetic neutral atom (ENA) measurements from Polar to calculate the total ENA energy escape. To get the total ENA escape we apply a forward modeling technique, and to estimate the total ring current energy escape we use the Dessler-Parker-Sckopke relationship. …

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Particle Size Determination: An Undergraduate Lab In Mie Scattering, I. Weiner '01, M. Rust '01, Thomas D. Donnelly Feb 2001

Particle Size Determination: An Undergraduate Lab In Mie Scattering, I. Weiner '01, M. Rust '01, Thomas D. Donnelly

All HMC Faculty Publications and Research

A technique for determining the size of microscopic spherical particles using light scattering is presented as an undergraduate physics lab. Scatterer size is determined from angular scattering distribution measurements of laser light scattered from a dilute suspension of latex spheres with diameters of 4.99±0.05 and 6.038±0.045 μm. Previous experiments of this type used approximate theoretical corrections and required the construction of specialized sample cells to minimize complicating effects. As a significant improvement to these, we generate angular scattering distributions from Mie theory and, using an accurate numerical procedure, correct these distributions for Snell’s law and foreshortening effects. Scatterer size …

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Measurement Of The Top Quark Mass With The Collider Detector At Fermilab, T. Affolder, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration Feb 2001

Measurement Of The Top Quark Mass With The Collider Detector At Fermilab, T. Affolder, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration

Kenneth Bloom Publications

This report describes a measurement of the top quark mass in pp̅ collisions at a center of mass energy of 1.8 TeV. The data sample was collected with the CDF detector during the 1992–1995 collider run at the Fermilab Tevatron, and corresponds to an integrated luminosity of 106 pb-1. Candidate tt̅ events in the ‘‘lepton+jets’’ decay channel provide our most precise measurement of the top quark mass. For each event a top quark mass is determined by using energy and momentum constraints on the production of the tt̅ pair and its subsequent decay. A likelihood fit to the …

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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.

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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 …

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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.

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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]

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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.

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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 …

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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.

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