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1994

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Articles 61 - 90 of 350

Full-Text Articles in Physics

On The Discretized Light Cone Quantization Of Electrodynamics, Alex C. Kalloniatis, David G. Robertson Oct 1994

On The Discretized Light Cone Quantization Of Electrodynamics, Alex C. Kalloniatis, David G. Robertson

Physics Faculty Scholarship

Discretized light-cone quantization of (3+1)-dimensional electrodynamics is discussed, with careful attention paid to the interplay between gauge choice and boundary conditions. In the zero longitudinal momentum sector of the theory a general gauge fixing is performed, and the corresponding relations that determine the zero modes of the gauge field are obtained. One particularly natural gauge choice in the zero mode sector is identified, for which the constraint relations are simplest and the fields may be taken to satisfy the usual canonical commutation relations. The constraints are solved in perturbation theory, and the Poincaré generators Pμ are constructed. The ...


X-Ray Studies Of The Hexatic Phase In Liquid-Crystals With A Crystal-B-Hexatic-B-Smectic-A Phase Sequence, Ewa Gorecka, Li Chen, Wieslaw Pyzuk, Adam Krowczynski, Satyendra Kumar Oct 1994

X-Ray Studies Of The Hexatic Phase In Liquid-Crystals With A Crystal-B-Hexatic-B-Smectic-A Phase Sequence, Ewa Gorecka, Li Chen, Wieslaw Pyzuk, Adam Krowczynski, Satyendra Kumar

Physics Publications

Free-standing monodomain thick films of three liquid crystalline compounds were examined by x-ray scattering. These compounds exhibit a unique enantiotropic crystal-B-hexatic-B-smectic-A phase sequence with no evidence of herringbone order. The hexatic order parameter Cg changes in the hexatic phase with critical exponent beta=0.15+/-0.03. Temperature dependence of the in-plane positional order correlation length suggests a strongly first-order hexatic-B to crystal-B phase transition with indiscernible enthalpy change.


Spontaneous Structure Formation In Driven Systems With Two Species: Exact Solutions In A Mean-Field Theory, I. Vilfan, R. K. P. Zia, Beate Schmittmann Oct 1994

Spontaneous Structure Formation In Driven Systems With Two Species: Exact Solutions In A Mean-Field Theory, I. Vilfan, R. K. P. Zia, Beate Schmittmann

Beate Schmittmann

A stochastic lattice gas of particles, subject to an excluded volume constraint and to a uniform external driving field, is investigated. Using a mean-field theory for a system with equal number of oppositely charged particles, exact results are obtained. Focusing on the current-vs-density plot, we propose an explanation for the discontinuous transition found in earlier simulations. A critical value of the drive, below which this transition becomes continuous, is found. These results are supported by a bifurcation analysis, leading to an equation of motion for the amplitude of the soft mode.


Excited Heavy Baryons In The Bound State Picture, Joseph Schechter, Anand Subbaraman Oct 1994

Excited Heavy Baryons In The Bound State Picture, Joseph Schechter, Anand Subbaraman

Physics

The orbitally excited heavy quark baryons are studied in the Callan Klebanov bound state model with heavy spin symmetry. First, a compact description of the large N_c, infinite heavy quark mass bound state wavefunctions and the collective quantization is given. In order to study the kinematical corrections due to finite masses we motivate an approximate Schrodinger-like equation for the bound state. The effective potential in this equation is compared with the quadratic approximation (spherical harmonic oscillator) to it. This oscillator approximation is seen to be not very accurate. It is noted that the present experimental information cannot be even qualitatively ...


Low-Frequency Line Shapes In Guided Acoustic-Wave Brillouin Scattering, Benjamin I. Greene, Peter N. Saeta Oct 1994

Low-Frequency Line Shapes In Guided Acoustic-Wave Brillouin Scattering, Benjamin I. Greene, Peter N. Saeta

All HMC Faculty Publications and Research

Guided acoustic‐wave Brillouin scattering (GAWBS) measurements were performed on 20‐cm lengths of optical fibers with particular attention focused on the lowest lying resonance. In 125‐μm‐diam silica fibers, this resonance was observed to occur at ~22 MHz and have a line shape which varied erratically from sample to sample. Significant line shape fluctuations were evident even between sequential samples from the same fiber spool. We speculate that the observed effects are attributable to 0.01-0.1 μm distributed geometric deviations from a perfect cylinder.


Boundary Conditions For The Diffusion Equation In Radiative Transfer, Richard C. Haskell, Lars O. Svaasand, Tsong-Tseh Tsay, Ti-Chen Feng, Matthew S. Mcadams, Bruce J. Tromberg Oct 1994

Boundary Conditions For The Diffusion Equation In Radiative Transfer, Richard C. Haskell, Lars O. Svaasand, Tsong-Tseh Tsay, Ti-Chen Feng, Matthew S. Mcadams, Bruce J. Tromberg

All HMC Faculty Publications and Research

Using the method of images, we examine the three boundary conditions commonly applied to the surface of a semi-infinite turbid medium. We find that the image-charge configurations of the partial-current and extrapolated-boundary conditions have the same dipole and quadrupole moments and that the two corresponding solutions to the diffusion equation are approximately equal. In the application of diffusion theory to frequency-domain photon-migration (FDPM) data, these two approaches yield values for the scattering and absorption coefficients that are equal to within 3%. Moreover, the two boundary conditions can be combined to yield a remarkably simple, accurate, and computationally fast method for ...


Band Dispersion In C60(111): An Angle-Resolved Photoemission Study, P. J. Benning, C. G. Olson, David W. Lynch, J. H. Weaver Oct 1994

Band Dispersion In C60(111): An Angle-Resolved Photoemission Study, P. J. Benning, C. G. Olson, David W. Lynch, J. H. Weaver

Physics and Astronomy Publications

Angle-resolved photoemission studies of single-crystal C60(111) films grown on GeS(001) reveal changes in valence feature line shape with emission angle and photon energy that are indicative of band dispersion. For an excitation energy (hν) of 10 eV, normal emission spectra show four sharp structures within the ∼1.1-eV-wide valence feature derived from the second highest molecular orbital (HOMO-1) of C60. For hν=8.1 eV, the 1-eV-wide HOMO-derived feature exhibits changes with emission angle mainly due to dispersion of 0.6 eV in the unoccupied bands. The distribution of electronic states underlying HOMO and HOMO-1 indicates ...


Quantum Electromagnetic Wormholes And Geometrical Description Of The Electric Charge, Marco Cavaglia Oct 1994

Quantum Electromagnetic Wormholes And Geometrical Description Of The Electric Charge, Marco Cavaglia

Physics Faculty Research & Creative Works

I present and discuss a class of solutions of the Wheeler-DeWitt equation describing wormholes generated by coupling of gravity to the electromagnetic field for Kantowski-Sachs and Bianchi type-I spacetimes. Since the electronic charge can be viewed as electric lines of force trapped in a finite region of spacetime, these solutions can be interpreted as the quantum corresponding to the Einstein-Rosen-Misner-Wheeler electromagnetic geon.


Diamagnetic Shifts Of Excitons Associated With Symmetrical And Antisymmetric Wave Functions In Coupled Inxga1-Xas-Gaas Quantum Wells, D. C. Reynolds, David C. Look, B. Jogai, C. E. Stutz Oct 1994

Diamagnetic Shifts Of Excitons Associated With Symmetrical And Antisymmetric Wave Functions In Coupled Inxga1-Xas-Gaas Quantum Wells, D. C. Reynolds, David C. Look, B. Jogai, C. E. Stutz

Physics Faculty Publications

Magneto‐optical data obtained from photoluminescence and photoluminescence excitation measurements performed in the presence of applied magnetic fields were used to determine the diamagnetic shifts of free excitons. The samples studied were coupled InxGa1−xAs–GaAs quantum wells. In all cases the excitons associated with antisymmetric wave functions were found to have larger diamagnetic shifts than the excitons associated with symmetric wave functions. This suggests that the excitons associated with antisymmetric wave functions have a smaller binding energy than excitons associated with symmetric wave functions. These properties are consistent with the fact that excitons associated with ...


Magnetoluminescence Studies In Gaas-Alxga1-Xas Single Heterojunctions - Observation Of Parity-Forbidden Landau-Level Transitions, D. C. Reynolds, David C. Look, B. Jogai, C. E. Stutz, R. Jones, K. K. Bajaj Oct 1994

Magnetoluminescence Studies In Gaas-Alxga1-Xas Single Heterojunctions - Observation Of Parity-Forbidden Landau-Level Transitions, D. C. Reynolds, David C. Look, B. Jogai, C. E. Stutz, R. Jones, K. K. Bajaj

Physics Faculty Publications

We have observed a number of allowed and parity-forbidden Landau-level transitions in a modulation-doped GaAs-AlxGa1-xAs single heterojunction structure using photoluminescence-excitation spectroscopy at 2 K. The GaAs layer in this structure is 5000 Å thick. From the allowed Landau-level transitions we determine the reduced mass of the electron-hole pair to be 0.07me. Using a heavy-hole mass of 0.45me, we determine the average value of the electron effective mass to be 0.084me. From the parity-forbidden transitions where the hole Landau level is the same but the electron Landau levels are different, we ...


Nondestructive Mapping Of Carrier Concentration And Dislocation Density In N(+)-Type Gaas, David C. Look, D. C. Walters, M. G. Mier, J. R. Sizelove Oct 1994

Nondestructive Mapping Of Carrier Concentration And Dislocation Density In N(+)-Type Gaas, David C. Look, D. C. Walters, M. G. Mier, J. R. Sizelove

Physics Faculty Publications

Transmission mappings (500 μm×500 μm resolution) at wavelengths of 0.9–1.5 μm on 3 in., n+‐GaAs wafers (n≂1–2×1018 cm-3) correlate well with carrier concentration n, measured by the Hall effect, and dislocation density, as confirmed by KOH etch‐pit patterns. The absorption for λ≳1.0 μm (below band edge) varies directly with n via free‐carrier interconduction‐band transitions, while the absorption for λ≲0.95 μm (near band edge) varies inversely with n because of band‐filling effects. Both phenomena are highly useful for n+‐GaAs wafer characterization.


X-Ray Studies Of The Hexatic Phase In Liquid Crystals With A Crystal-B–Hexatic-B–Smectic-A Phase Sequence, Ewa Górecka, Li Chen, Wiesław Pyżuk, Adam Krówczyński, Satyendra Kumar Oct 1994

X-Ray Studies Of The Hexatic Phase In Liquid Crystals With A Crystal-B–Hexatic-B–Smectic-A Phase Sequence, Ewa Górecka, Li Chen, Wiesław Pyżuk, Adam Krówczyński, Satyendra Kumar

Physics Publications

Free-standing monodomain thick films of three liquid crystalline compounds were examined by x-ray scattering. These compounds exhibit a unique enantiotropic crystal-B–hexatic-B–smectic-A phase sequence with no evidence of herringbone order. The hexatic order parameter C6 changes in the hexatic phase with critical exponent β=0.15±0.03. Temperature dependence of the in-plane positional order correlation length suggests a strongly first-order hexatic-B to crystal-B phase transition with indiscernible enthalpy change.


Dosimetry Of High-Energy Heavy-Ion Beams Using Energy-Dependent Green's Functions, Sang Yull Chun Oct 1994

Dosimetry Of High-Energy Heavy-Ion Beams Using Energy-Dependent Green's Functions, Sang Yull Chun

Physics Theses & Dissertations

A theoretical description of the transport of high-charge and high-energy (HZE) ion bombardment of biological tissue is developed. The energy-dependent Green’s functions and particle fluxes are obtained for two boundary distributions - the monoenergetic and the Gaussian. Approximate energy-dependent Green’s functions for the collision terms are obtained for computational simplicity. As an application of the energy-dependent Green’s function method, dosimetric quantities, such as dose, dose-equivalent, and average quality factor, for 600A MeV56Fe , 517A MeV 40Ar, and 625A MeV 20Ne ion beams incident on a water target are obtained and compared with the values obtained ...


Simulation Of Active Control Of Asymmetric Flows Around Slender Pointed Forebodies, Hazem Sharaf El-Din Oct 1994

Simulation Of Active Control Of Asymmetric Flows Around Slender Pointed Forebodies, Hazem Sharaf El-Din

Mechanical & Aerospace Engineering Theses & Dissertations

At high angles of attack, the flowfield over slender forebodies becomes asymmetric with substantial side force, which may exceed the available control capability. The unsteady compressible Navier-Stokes equations are used to investigate the effectiveness of different active control methods to alleviate and possibly eliminate the flow asymmetry and the subsequent side force. Although the research work focuses on active control methods, a passive control method has been investigated. The implicit, Roe flux-difference splitting, finite volume scheme is used for the numerical computations. Both locally-conical and three-dimensional solutions of the Navier-Stokes equations are obtained.

The asymmetric flow over five-degree semi-apex angle ...


Time-Resolved Electron Temperature Measurement In A Highly-Excited Gold Target Usingfemtosecond Thermionic Emission, W. Y. Wang, D. Mark Riffe, Y. S. Lee, M. C. Downer Sep 1994

Time-Resolved Electron Temperature Measurement In A Highly-Excited Gold Target Usingfemtosecond Thermionic Emission, W. Y. Wang, D. Mark Riffe, Y. S. Lee, M. C. Downer

All Physics Faculty Publications

We report direct measurement of hot-electron temperatures and relaxation dynamics for peak electron temperatures between 3400 and 11 000 K utilizing two-pulse-correlation femtosecond (fs) thermionic emission. The fast relaxation times (<1.5 ps) are described by extending RT characterizations of the thermal conductivity, electron-phonon coupling, and electronic specific heat to these high electron temperatures.


Novel Methods For The Fabrication Of Ferromagnetic Nickel And Nickel Boride Thin Films, D. Zych, A. Patwa, S.S. Kher, N.M. Boag, Peter A. Dowben Sep 1994

Novel Methods For The Fabrication Of Ferromagnetic Nickel And Nickel Boride Thin Films, D. Zych, A. Patwa, S.S. Kher, N.M. Boag, Peter A. Dowben

Peter Dowben Publications

Metal-rich nickel boride thin films fabricated from boron-containing precursor compounds by a cluster deposition process are shown to be ferromagnetic. The metal-rich films fabricated by this approach exhibit hysteresis curves similar to those obtained for pure nickel foils. These films are a mixture of pure nickel and the Ni3B nickel boride phases. It is postulated that the hysteresis curves with smaller remnant magnetizations obtained from these films are a consequence of Ni3B inclusions within the films. Other novel organometallic source compounds for nickel chemical-vapor deposition are briefly reviewed. Journal of Applied Physics is copyrighted by The ...


Strongly Interacting Longitudinal Gauge Bosons In Supersymmetric Models, T Clark, Tonnis Ter Veldhuis Sep 1994

Strongly Interacting Longitudinal Gauge Bosons In Supersymmetric Models, T Clark, Tonnis Ter Veldhuis

Tonnis ter Veldhuis

No abstract provided.


Superelastic And Inelastic He2++He State-Selective Electron Capture, V. D. Irby, Timothy J. Gay, J. T. Park, S. W. Bross, A. D. Gaus Sep 1994

Superelastic And Inelastic He2++He State-Selective Electron Capture, V. D. Irby, Timothy J. Gay, J. T. Park, S. W. Bross, A. D. Gaus

Timothy J. Gay Publications

Experimental studies have been made of superelastic and inelastic collision processes involved in the state-selective single-electron capture reaction 3He2++He(1 1S)→ +He+(n)+He+(n’), where n and n’ are the final principal quantum-number states of the collision products. Total cross sections have been measured at projectile energies of 15, 30, and 45 keV/u, by examining the energy loss-gain of the fast 3He+ product ions, for the superelastic n=n’=1 channel, and for the sum of the inelastic n=2, n’=1 and n=1, n’=2 states. Measurements are also presented for ...


Neutron-Diffraction And Mössbauer Effect Study Of The Tb2Fe17-XAlX Solid Solutions, Gaya Kanishka Marasinghe, Sanjay R. Mishra, Oran Allan Pringle, Gary J. Long, Zhong Bo Hu, William B. Yelon, Fernande Grandjean, D. P. Middleton, K. H. J. Buschow Sep 1994

Neutron-Diffraction And Mössbauer Effect Study Of The Tb2Fe17-XAlX Solid Solutions, Gaya Kanishka Marasinghe, Sanjay R. Mishra, Oran Allan Pringle, Gary J. Long, Zhong Bo Hu, William B. Yelon, Fernande Grandjean, D. P. Middleton, K. H. J. Buschow

Physics Faculty Research & Creative Works

The magnetic properties of a series of Tb2Fe17-xAlx solid solutions, with nominal x compositions of 0, 2, 3, 4, 5, 6, 7, and 8, have been studied by neutron diffraction and Mössbauer spectroscopy. Neutron-diffraction data indicate that the compounds all crystallize with the Th2Zn17 structure and that the aluminum atoms are excluded from the 9d site and show a distinct preference for the 6c site only for an aluminum content greater than 6. The unit-cell volume increases by approximately 1% per aluminum atom substituted in the formula unit. The magnetic moment per ...


Differential Double Excitation Cross Sections In Proton-Helium Collisions Studied By Energy-Loss Spectroscopy, W. T. Htwe, Tibor Vajnai, M. Barnhart, A. D. Gaus, Michael Schulz Sep 1994

Differential Double Excitation Cross Sections In Proton-Helium Collisions Studied By Energy-Loss Spectroscopy, W. T. Htwe, Tibor Vajnai, M. Barnhart, A. D. Gaus, Michael Schulz

Physics Faculty Research & Creative Works

We have measured ion energy-loss spectra for 150 keV proton-helium collisions as a function of the projectile scattering angle. From the data we obtained double excitation cross sections differential in the proton scattering angle as well as the ratios of both double excitation and single ionization to single excitation. In these ratios pronounced peak structures are observed at about 0.7 mrad. Two alternative interpretations of these peak structures are offered: They may be due to binary collisions between the projectile and the target electrons, or they could be a manifestation of an interference between different transition amplitudes leading to ...


Clean Ultrahigh Vacuum System With Single-Structure Diffusion Pumps, Timothy J. Gay, M.C. Fritts, J.E. Furst, M.A. Khakoo, E.R. Mell, M.T. Seiger, M.W.K.P. Wijayaratna Sep 1994

Clean Ultrahigh Vacuum System With Single-Structure Diffusion Pumps, Timothy J. Gay, M.C. Fritts, J.E. Furst, M.A. Khakoo, E.R. Mell, M.T. Seiger, M.W.K.P. Wijayaratna

Timothy J. Gay Publications

A practical example of the use of single-structure diffusion pumping groups in an experiment requiring hydrocarbon-free, ultrahigh vacuum is presented. With the use of proper vacuum procedures and careful foreline design and operation, but with no exotic hardware or liquid nitrogen, we have demonstrated that such a pump could provide vacuum that was "clean," i.e., which had no residual pump-oil contamination to a partial pressure below 10-8 mbar. Their use is thus compatible, at least in peripheral vacuum chambers, with standard "UHV-surface science" processes. We discuss our vacuum system in detail, and present a review of the literature ...


Clean Ultrahigh Vacuum System With Single-Structure Diffusion Pumps, Timothy J. Gay, M.C. Fritts, J.E. Furst, M.A. Khakoo, E.R. Mell, M.T. Seiger, M.W.K.P. Wijayaratna Sep 1994

Clean Ultrahigh Vacuum System With Single-Structure Diffusion Pumps, Timothy J. Gay, M.C. Fritts, J.E. Furst, M.A. Khakoo, E.R. Mell, M.T. Seiger, M.W.K.P. Wijayaratna

Timothy J. Gay Publications

A practical example of the use of single-structure diffusion pumping groups in an experiment requiring hydrocarbon-free, ultrahigh vacuum is presented. With the use of proper vacuum procedures and careful foreline design and operation, but with no exotic hardware or liquid nitrogen, we have demonstrated that such a pump could provide vacuum that was "clean," i.e., which had no residual pump-oil contamination to a partial pressure below 10-8 mbar. Their use is thus compatible, at least in peripheral vacuum chambers, with standard "UHV-surface science" processes. We discuss our vacuum system in detail, and present a review of the literature on ...


Radiative Recombination At The Alxga1-Xas-Gaas Heterostructure Interface By 2-Dimensional Excitons, D. C. Reynolds, David C. Look, B. Jogai, Phil W. Yu, K. Evans, C. E. Stutz, L. Radomsky Sep 1994

Radiative Recombination At The Alxga1-Xas-Gaas Heterostructure Interface By 2-Dimensional Excitons, D. C. Reynolds, David C. Look, B. Jogai, Phil W. Yu, K. Evans, C. E. Stutz, L. Radomsky

Physics Faculty Publications

Radiative recombination from the AlxGa1-xAs-GaAs heterostructure interface was investigated using photoluminescence and photoluminescence-excitation spectroscopy in modulation-doped and undoped samples. This emission is identified as H-band A, resulting from an indirect excitonlike transition in real space. The exciton is made up of a two-dimensional electron in the interface notch and a valence-band hole in the neutral region, having a binding energy of 1.8 meV. The H-band A exciton is directly excited by a free exciton making a vertical transition in real space. H-band A may be a distortion of the vertical direct free exciton in real ...


Rigorous Justification Of The Localized Approximation To The Beam Shape Coefficients In Generalized Lorenz-Mie Theory .1. On-Axis Beams, James A. Lock, Gérard Gouesbet Sep 1994

Rigorous Justification Of The Localized Approximation To The Beam Shape Coefficients In Generalized Lorenz-Mie Theory .1. On-Axis Beams, James A. Lock, Gérard Gouesbet

Physics Faculty Publications

Generalized Lorenz-Mie theory describes electromagnetic scattering of an arbitrary light beam by a spherical particle. The computationally most expensive feature of the theory is the evaluation of the beam-shape coefficients, which give the decomposition of the incident light beam into partial waves. The so-called localized approximation to these coefficients for a focused Gaussian beam is an analytical function whose use greatly simplifies Gaussian-beam scattering calculations. A mathematical justification and physical interpretation of the localized approximation is presented for on-axis beams.


X-Ray Studies Of Bond-Orientational Order In Liquid-Crystalline Orthogonal Hexatic-B Phase, E. Gorecka, Li Chen, Oleg Lavrentovich, W. Pyzuk Aug 1994

X-Ray Studies Of Bond-Orientational Order In Liquid-Crystalline Orthogonal Hexatic-B Phase, E. Gorecka, Li Chen, Oleg Lavrentovich, W. Pyzuk

Oleg Lavrentovich

X-ray scattering measurements have been carried out for free-standing, thick . monodomain films of the orthogonal hexatic-B phase. From Fourier analysis of X-scans, 6n-fold-symmetry order parameters were determined and proved to fulfill the scaling relation C6n = C6n+lambdan(n-1). The temperature behavior of C6 and lambda was found nonuniversal when comparing homologues, PIR5 and PIR7, differing in their range of the hexatic phase. The hexatic order parameter varies with the critical exponents 0.25, 0.20 (+/- 0.03), respectively. For comparison results for compound RFL6, of other homologue series, are presented.


Nanometer Scale Patterning And Oxidation Of Silicon Surfaces With An Ultrahigh Vacuum Scanning Tunneling Microscope, J. W. Lyding, G. C. Abeln, T. -C. Shen, C. Wang, J. R. Tucker Aug 1994

Nanometer Scale Patterning And Oxidation Of Silicon Surfaces With An Ultrahigh Vacuum Scanning Tunneling Microscope, J. W. Lyding, G. C. Abeln, T. -C. Shen, C. Wang, J. R. Tucker

T. -C. Shen

Nanoscale patterning of the Si(100)‐2×1 monohydride surface has been achieved by using an ultrahigh vacuum (UHV) scanning tunneling microscope(STM) to selectively desorb the hydrogen passivation. Hydrogen passivation on silicon represents one of the simplest possible resist systems for nanolithography experiments. After preparing high quality H‐passivated surfaces in the UHV chamber, patterning is achieved by operating the STM in field emission. The field emitted electrons stimulate the desorption of molecular hydrogen, restoring clean Si(100)‐2×1 in the patterned area. This depassivation mechanism seems to be related to the electron kinetic energy for patterning at ...


Stripe Domain Phase Of A Thin Nematic Film And The K13 Divergence Term, Oleg Lavrentovich, V. M. Pergamenshchik Aug 1994

Stripe Domain Phase Of A Thin Nematic Film And The K13 Divergence Term, Oleg Lavrentovich, V. M. Pergamenshchik

Chemical Physics Publications

To verify the status of the divergence K13 term in the elastic theory of liquid crystals we study submicron films placed onto an isotropic fluid substrate in the Langmuir trough (Langmuir liquid crystal, LLC). The upper and lower surfaces favor normal and tangential molecular orientation, respectively. The periodic domain phase is observed in a nematic LLC. The dependence of the periodicity L of the domains vs film thickness h can be explained only if the elastic energy is accompanied by divergence terms with nonzero constants K13 and K24. It is found that for 5CB K13 almost-equal-to -0.2K11.


Light Cone Quantization Of Electrodynamics, David G. Robertson Aug 1994

Light Cone Quantization Of Electrodynamics, David G. Robertson

Physics Faculty Scholarship

Light-cone quantization of (3+1)-dimensional electrodynamics is discussed, using discretization as an infrared regulator and paying careful attention to the interplay between gauge choice and boundary conditions. In the zero longitudinal momentum sector of the theory a general gauge fixing is performed and the corresponding relations that determine the constrained modes of the gauge field are obtained. The constraints are solved perturbatively and the structure of the theory is studied to lowest nontrivial order.


Light Front Qcd And The Constituent Quark Model, Kenneth G. Wilson, David G. Robertson Aug 1994

Light Front Qcd And The Constituent Quark Model, Kenneth G. Wilson, David G. Robertson

Physics Faculty Scholarship

A general strategy is described for deriving a constituent approximation to QCD, inspired by the constituent quark model and based on light-front quantization. Some technical aspects of the approach are discussed, including a mechanism for obtaining a confining potential and ways in which spontaneous chiral symmetry breaking can be manifested


Dissociative Attachment In Selected Monochloroalkanes, D. M. Pearl, Paul Burrow Aug 1994

Dissociative Attachment In Selected Monochloroalkanes, D. M. Pearl, Paul Burrow

Paul Burrow Publications

The total cross sections for the dissociative attachment (DA) process are reported for eight normal chloroalkanes CnH2n+1Cl for n=2–9, two secondary compounds 2-chloropropane and 2-chlorobutane, one tertiary compound t-butyl chloride, and three cyclic chloroalkanes c-CnH2n-1Cl for n=4–6, for electron energies below 4 eV. Using vertical attachment energies (VAEs) determined by electron transmission spectroscopy elsewhere and in this work, we show that the resonance widths vary linearly with VAE in this series of compounds and that the peak DA cross sections decline exponentially with ...