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Selected Works

1997

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Articles 1 - 28 of 28

Full-Text Articles in Physics

Photolithographic Patterning Of Vacuum-Deposited Organic Light Emitting Devices, Peifang Tian, P. E. Burrows, S. E. Forrest Nov 1997

Photolithographic Patterning Of Vacuum-Deposited Organic Light Emitting Devices, Peifang Tian, P. E. Burrows, S. E. Forrest

Peifang Tian

We demonstrate a photolithographic technique to fabricate vacuum-deposited organic light emitting devices. Photoresist liftoff combined with vertical deposition of the emissive organic materials and the metal cathode, followed by oblique deposition of a metal cap, avoids the use of high processing temperatures and the exposure of the organic materials to chemical degradation. The unpackaged devices show no sign of deterioration in room ambient when compared with conventional devices fabricated using low-resolution, shadow mask patterning. Furthermore, the devices are resistant to rapid degradation when operated in air for extended periods. This work illustrates a potential foundation for the volume production of ...


Empirical Models Of Storm-Time Equatorial Zonal Electric Fields, Bela G. Fejer, L. Scherliess Oct 1997

Empirical Models Of Storm-Time Equatorial Zonal Electric Fields, Bela G. Fejer, L. Scherliess

Bela G. Fejer

Ionospheric plasma drifts often show highly complex and variable signatures during geomagnetically active periods due to the effects of different disturbance processes. We describe initially a methodology for the study of storm time dependent ionospheric electric fields. We present empirical models of equatorial disturbance zonal electric fields obtained using extensive F region vertical plasma drift measurements from the Jicamarca Observatory and auroral electrojet indices. These models determine the plasma drift perturbations due to the combined effects of short-lived prompt penetration and longer lasting disturbance dynamo electric fields. We show that the prompt penetration drifts obtained from a high time resolution ...


Deuteron Threshold Electrodisintegration At High Momentum Transfer, W M. Schmitt, K S. Lee, H Baghaei, S Churchwell, R S. Hicks, R Miskimen, Gerald Alvin Peterson, K Wang Sep 1997

Deuteron Threshold Electrodisintegration At High Momentum Transfer, W M. Schmitt, K S. Lee, H Baghaei, S Churchwell, R S. Hicks, R Miskimen, Gerald Alvin Peterson, K Wang

Gerald Alvin Peterson

Absolute differential cross sections for the threshold electrodisintegration of the deuteron with good resolution were measured at a laboratory scattering angle of 160° for five values of Q2 ranging from 8.66 to 42.4fm-2. Comparisons of the data averaged over Enp from 0 to 3 MeV and from 0 to10 MeV are made with nonrelativistic meson exchange calculations. These calculations are sensitive to the nucleon electromagnetic form factors, nucleon-nucleon potential, and relativistic effects. The data are also compared with a hybrid quark-hadron model calculation that describes the deuteron as a six-quark cluster for the short range part of the ...


Precision Determination Of The Neutron Spin Structure Function G1n, K Abe, C M. Berisso, S Churchwell, R S. Hicks, Yu G. Kolomensky, Gerald Alvin Peterson Jul 1997

Precision Determination Of The Neutron Spin Structure Function G1n, K Abe, C M. Berisso, S Churchwell, R S. Hicks, Yu G. Kolomensky, Gerald Alvin Peterson

Gerald Alvin Peterson

We report on a precision measurement of the neutron spin structure function g1n using deep inelastic scattering of polarized electrons by polarized 3He. For the kinematic range 0.014


Features Of The Photon Statistics Of Two Coupled Electromagnetic Field Modes Under The Conditions Of Strong Mode Coupling, Mikhail E. Veisman, Serguei Y. Kalmykov Jun 1997

Features Of The Photon Statistics Of Two Coupled Electromagnetic Field Modes Under The Conditions Of Strong Mode Coupling, Mikhail E. Veisman, Serguei Y. Kalmykov

Serge Youri Kalmykov

The probabilities of transitions between the Fock states of two electromagnetic field modes under the influence of coupling between modes of finite duration are investigated. It is shown that the transition probability is a strongly oscillating function of the mode numbers of the photons. Under conditions in which the coupling frequency exceeds the geometric mean of the mode frequencies (strong coupling), large numbers of photons are excited in the mode with the lower frequency. The excitation of a two-dimensional radiation field oscillator and the ‘‘red’’ symmetry of the transition probabilities can be attributed to instability of the classical two-dimensional oscillator ...


A Surface-Emitting Vacuum-Deposited Organic Light Emitting Device, V. Bulovic, Peifang Tian, P. E. Burrows, M. R. Gokhale, S. R. Forrest, M. E. Thompson Jun 1997

A Surface-Emitting Vacuum-Deposited Organic Light Emitting Device, V. Bulovic, Peifang Tian, P. E. Burrows, M. R. Gokhale, S. R. Forrest, M. E. Thompson

Peifang Tian

We demonstrate a vacuum-deposited organic light emitting device which emits from its top surface through a transparent indium-tin-oxide anode. This device employs a novel protective cap layer which prevents damage to the organic layers during sputter deposition of the anode, while also improving hole injection. Mechanisms of current transport and carrier injection from the contacts are investigated. This device configuration allows for integration of organic light emitting devices with n-channel field effect transistors used in display active matrix backplanes.


Production Of Η Mesons In Double Pomeron Exchange, Alec Schramm, Daniel Reeves May 1997

Production Of Η Mesons In Double Pomeron Exchange, Alec Schramm, Daniel Reeves

Alec J Schramm

We estimate the production cross section for ηc and ηb mesons via Pomeron-Pomeron fusion in peripheral heavy-ion collisions. Total and elastic PP cross sections are calculated in an equivalent Pomeron approximation.


Correlated And Coherent States Of The Two-Dimensional Quantum Oscillator With A Nonstationary Mode Coupling, Mikhail E. Veisman, Serguei Y. Kalmykov Apr 1997

Correlated And Coherent States Of The Two-Dimensional Quantum Oscillator With A Nonstationary Mode Coupling, Mikhail E. Veisman, Serguei Y. Kalmykov

Serge Youri Kalmykov

We investigate the squeezing and correlation phenomena of quantum fluctuations in correlated coherent states of a system of two oscillatory modes with a parametric coupling of the coordinates. In the regime of strong coupling between the modes, we discover an excitation and a strong correlation of the quantum fluctuations. The matrix of dispersions and covariances of the coordinates and momenta is found explicitly with the help of the method of the linear quantum integrals of motion.


Effects Of Low Polymer Content In A Liquid-Crystal Microlens, Toshiaki Nose, Shin Masuda, Susumu Sato, Jianlin Li, Liang-Chy Chien, Philip Bos Mar 1997

Effects Of Low Polymer Content In A Liquid-Crystal Microlens, Toshiaki Nose, Shin Masuda, Susumu Sato, Jianlin Li, Liang-Chy Chien, Philip Bos

Liang-Chy Chien

A small number of bifunctional monomers are mixed with a nematic liquid crystal (LC) and cured with a distributed electric field, which is produced by a circular-hole-patterned electrode structure. A gradient type of lens, that is, a LC microlens, is investigated for various polymer concentrations. Addition of 3% polymer is enough to freeze the gradient-index properties of the structure in the form of a convex lens, and a polymer-stabilized LC microlens is demonstrated. Although a lower concentration of polymer cannot hold the distribution properties in a curing process, it can maintain the variable focus as a nematic material can. The ...


Effects Of Low Polymer Content In A Liquid-Crystal Microlens, Toshiaki Nose, Shin Masuda, Susumu Sato, Jianlin Li, Liang-Chy Chien, Philip J. Bos Mar 1997

Effects Of Low Polymer Content In A Liquid-Crystal Microlens, Toshiaki Nose, Shin Masuda, Susumu Sato, Jianlin Li, Liang-Chy Chien, Philip J. Bos

Philip J. Bos

A small number of bifunctional monomers are mixed with a nematic liquid crystal (LC) and cured with a distributed electric field, which is produced by a circular-hole-patterned electrode structure. A gradient type of lens, that is, a LC microlens, is investigated for various polymer concentrations. Addition of 3% polymer is enough to freeze the gradient-index properties of the structure in the form of a convex lens, and a polymer-stabilized LC microlens is demonstrated. Although a lower concentration of polymer cannot hold the distribution properties in a curing process, it can maintain the variable focus as a nematic material can. The ...


Two-Photon Optogalvanic Spectra Of Argon: Odd Parity Rydberg States, Naveed Piracha, M. Baig, S. Khan, B. Suleman Mar 1997

Two-Photon Optogalvanic Spectra Of Argon: Odd Parity Rydberg States, Naveed Piracha, M. Baig, S. Khan, B. Suleman

Naveed K. Piracha

Extensive new data on the odd-parity, single-colour, two-photon optogalvanic spectra of argon in the visible region is reported using an excimer-pumped dye laser in conjunction with an argon discharge cell. The experimental technique enables us to record a pure two-photon spectrum in a region which is dominated by one-photon transitions. A large number of two-photon transitions, originating from the two metastable states [...] and [...] to the excited states of configurations [...] (J=0, 2) and [...] (J = 0 - 4) of argon, has been recorded and arranged into 10 Rydberg series. The interchannel interactions among the [...] and the [...], n d J = 2 channels and ...


Backward Stimulated Raman Scattering Of A Modulated Laser Pulse In Plasmas, Nikolai E. Andreev, Serguei Y. Kalmykov Mar 1997

Backward Stimulated Raman Scattering Of A Modulated Laser Pulse In Plasmas, Nikolai E. Andreev, Serguei Y. Kalmykov

Serge Youri Kalmykov

The specific features of backward stimulated Raman scattering (BSRS) of a short modulated (multi-frequency) laser pulse in underdense plasmas are studied. The effect of resonant suppression of the BSRS of higher frequency pulse components is explored. For an arbitrary pair of pulse components, in the conditions of weak coupling, it is demonstrated that the backscattering of a higher frequency laser pulse component is a five-wave resonant process at a frequency difference between the components close to the double plasma frequency. In the conditions of strong coupling the backscattering of neither pulse component is suppressed and the spectrum of the instability ...


Small Scale Electronic Transport In Diamond Microcrystals., M. Jaeger, S. Hyun, Anthony Day, M. Thorpe, B. Golding Feb 1997

Small Scale Electronic Transport In Diamond Microcrystals., M. Jaeger, S. Hyun, Anthony Day, M. Thorpe, B. Golding

Anthony Roy Day

The interpretation of electronic transport in polycrystalline diamond has proven difficult as a result of the disorder arising from physical and chemical inhomogeneities. We describe experimental methods, based on electron beam lithography, for studying transport in single crystallites grown by CVD on Si substrates. The electrical contacting process utilizes the flexibility of the scanning electron microscope to write metallic contacts to individual crystallites with lateral dimensions of a few μm. A detailed analysis of the current distribution in the crystals allows us to extract the electronic conductivity from arbitrarily shaped, faceted crystals.


Stiffness Of Measurement System And Significant Figures Of Displacement Which Are Required To Interpret Adhesional Force Curves, Nancy Burnham, Kunio Takahashi, Hubert Pollock, Tadao Onzawa Feb 1997

Stiffness Of Measurement System And Significant Figures Of Displacement Which Are Required To Interpret Adhesional Force Curves, Nancy Burnham, Kunio Takahashi, Hubert Pollock, Tadao Onzawa

Nancy A. Burnham

Force curves obtained from an elastic contact theory are shown and compared with experimental results. In the elastic contact theory, a pin-on-disk contact is assumed and the following interaction are taken into consideration; (i) elastic deformation, (ii) the specific energy of adhesion in the area of the contact, which is expressed as the difference between the surface energies and the interface energy, (iii) the long-range interaction outside the area of contact, assuming the additivity of the Lennard-Jones type potential, and (iv) another elastic term for the measurement system such as the cantilever stiffness of an atomic force microscope (AFM). In ...


Low Pressure Synthesis Of Bulk, Polycrystalline Gallium Nitride, Alberto Argoitia, Cliff C. Hayman, John C. Angus, Long Wang, Jeffrey S. Dyck, Kathleen Kash Jan 1997

Low Pressure Synthesis Of Bulk, Polycrystalline Gallium Nitride, Alberto Argoitia, Cliff C. Hayman, John C. Angus, Long Wang, Jeffrey S. Dyck, Kathleen Kash

Jeffrey Dyck

Thick films of polycrystalline GaN were grown at low pressures by direct reaction of atomic nitrogen with liquid Ga without the presence of a substrate. The crystals were confirmed to be wurtzitic GaN by x-ray diffraction, transmission electron microscopy, Raman spectroscopy, and elemental analysis. Photoluminescence spectra showed near band edge peaks and broad yellow band emission at both 298 and 10 K. The results show that atomic nitrogen is an attractive alternative to high pressure N2 for the saturation of liquid gallium with nitrogen for the synthesis of bulk GaN.


Midinfrared Electroluminescence In Gaas/Algaas Structures, G Strassar, P Kruck, M Helm, James Heyman, L Hvozdara, E Gornik Dec 1996

Midinfrared Electroluminescence In Gaas/Algaas Structures, G Strassar, P Kruck, M Helm, James Heyman, L Hvozdara, E Gornik

James Heyman

No abstract provided.


Diffusion Of Steroids In Porous Sol-Gel Glass: Application In Slow Drug Delivery, L. Sieminska, Matthew Ferguson, T. Zerda, E. Couch Dec 1996

Diffusion Of Steroids In Porous Sol-Gel Glass: Application In Slow Drug Delivery, L. Sieminska, Matthew Ferguson, T. Zerda, E. Couch

Matthew L. Ferguson

Samples of porous sol-gel glass, after being stabilized at 750± C, were impregnated with progesterone, estradiol, estrone, and hydrocortisone. Diffusion coefficients for those steroids inside the pores filled with pure ethanol, ethanol-water mixture or physiological solution were determined. It is shown that permeability is favored for steroids having fewer hydroxyl and carbonyl groups. Solvents that readily dissolve steroids increase the diffusion rate and thus the amount of delivered material. The flow of steroids in small pores is less restricted than in larger pores.


Synthesis Of Bulk, Polycrystalline Gallium Nitride At Low Pressures, Alberto Argoitia, John Angus, Cliff Hayman, Long Wang, Jeffrey Dyck, Kathleen Kash Dec 1996

Synthesis Of Bulk, Polycrystalline Gallium Nitride At Low Pressures, Alberto Argoitia, John Angus, Cliff Hayman, Long Wang, Jeffrey Dyck, Kathleen Kash

Jeffrey Dyck

Bulk, polycrytalline gallium nitride was crystallized from gallium saturated with nitrogen obtained from a microwave electron cyclotron resonance source. The polycrystalline samples are wurtzitic and n-type. Well-faceted crystals give near-band-edge and yellow band photo-luminescence at both 10K and 300K. The results show that atomic nitrogen is an attractive alternative to high pressure molecular nitrogen for saturation of gallium with nitrogen for synthesis of bulk gallium nitride.


Growth Of Bulk, Polycrystalline Gallium And Indium Nitride At Sub-Atmospheric Pressures, John Angus, Alberto Argoitia, Cliff Hayman, Long Wang, Jeffrey Dyck, Kathleen Kash Dec 1996

Growth Of Bulk, Polycrystalline Gallium And Indium Nitride At Sub-Atmospheric Pressures, John Angus, Alberto Argoitia, Cliff Hayman, Long Wang, Jeffrey Dyck, Kathleen Kash

Jeffrey Dyck

Bulk polycrystalline gallium nitride and indium nitride were crystallized at sub-atmospheric pressures by saturating the pure metals with nitrogen from a microwave electron cyclotron resonance source. Saturation of Ga/In melts with nitrogen led only to the crystallization of gallium nitride. The polycrystralline samples were wurtzitic. The gallium nitride was well faceted, with narrow Raman lineshapes, and showed near-band-edge and yellow band photo-luminescence at both 4K and 300K. The indium nitirde was formed in smaller amounts, was less well faceted, and showed no photoluminescence.


Influence Of The Nanocrystalline Surrounding On Impurity Optical Spectra In Mullite Glass‐ Ceramics And Model System Predictions, Jaan Männik, O. Sild, I. Sildos Dec 1996

Influence Of The Nanocrystalline Surrounding On Impurity Optical Spectra In Mullite Glass‐ Ceramics And Model System Predictions, Jaan Männik, O. Sild, I. Sildos

Jaan Männik

Numerical calculations of the inhomogeous distribution of electronic transition energies and a vibronic sideband of impurities substituted into a nanocrystal have been carried out. The investigation of the electronic levels of the impurities shows that some pseudolocal levels in the bulk turn to be localised levels in the case of nanocrystals. The appearance of different kind of surface optical vibrations in sideband of impurity spectrum specifie to nanocrystals has been found. In the experimental studies of mullite glass-ceramics we found that local disorder is the main reason of the inhomogeneous broadening of the R-like fluorescence line of the Cr3+ impurity ...


Chemical Kinetics In Low Pressure Acetylene Radio Frequency Glow Discharges, James Doyle Dec 1996

Chemical Kinetics In Low Pressure Acetylene Radio Frequency Glow Discharges, James Doyle

James R. Doyle

No abstract provided.


The Linear Potential Propagator, Br Holstein Dec 1996

The Linear Potential Propagator, Br Holstein

Barry R Holstein

The Feynman propagator for the case of a linear potential is evaluated by a variety of means.


The Elastic Moduli Of Random Networks: Calculations, Anthony Day Dec 1996

The Elastic Moduli Of Random Networks: Calculations, Anthony Day

Anthony Roy Day

No abstract provided.


Internal Forces In Nondegenerate 2d Electron Systems, Christopher Fang-Yen, M Dykman, M Lea Dec 1996

Internal Forces In Nondegenerate 2d Electron Systems, Christopher Fang-Yen, M Dykman, M Lea

Christopher Fang-Yen

No abstract provided.


A Nonlinear Deformed Su(2) Algebra With A Two-Color Quasitriangular Hopf Structure, Andrei Ludu Dec 1996

A Nonlinear Deformed Su(2) Algebra With A Two-Color Quasitriangular Hopf Structure, Andrei Ludu

Andrei Ludu

No abstract provided.


Final State Rescattering As A Contribution To B→ Ργ, John Donoghue, Eugene Golowich, Alexey Petrov Dec 1996

Final State Rescattering As A Contribution To B→ Ργ, John Donoghue, Eugene Golowich, Alexey Petrov

John Donoghue

We provide a new estimate of the long-distance component to the radiative transition B→py. Our mechanism involves the soft scattering of on-shell hadronic products of nonleptonic B decay, as in the chain B→pp→py. We employ a phenomenological fit to scattering data to estimate the effect. The specific intermediate states considered here modify the B→py decay rate at roughly the 528% level, although the underlying effect has the potential to be larger. Contrary to other mechanisms of long distance physics which have been discussed in the literature, this yields a non-negligible modification of the B0→r0g ...


Nonlinear Liquid Drop Model. Cnoidal Waves, Andrei Ludu Dec 1996

Nonlinear Liquid Drop Model. Cnoidal Waves, Andrei Ludu

Andrei Ludu

No abstract provided.


Anomalous Flow Profile Due To The Curvature Effect On Slip Length, Alejandro Garcia, K. Tibbs, F. Baras Dec 1996

Anomalous Flow Profile Due To The Curvature Effect On Slip Length, Alejandro Garcia, K. Tibbs, F. Baras

Alejandro Garcia

No abstract provided.