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Articles 781 - 810 of 1762
Full-Text Articles in Physical Sciences and Mathematics
The Evolution Of Ga And As Core Levels In The Formation Of Fe/Gaas (001): A High Resolution Soft X-Ray Photoelectron Spectroscopic Study, Tiehan H. Shen, Denis Greig, Mark Hopkinson, George Daniel Waddill, Jamie D. W. Thompson, James R. Neal, Simon A. Morton, James G. Tobin, Jim A. D. Matthew
The Evolution Of Ga And As Core Levels In The Formation Of Fe/Gaas (001): A High Resolution Soft X-Ray Photoelectron Spectroscopic Study, Tiehan H. Shen, Denis Greig, Mark Hopkinson, George Daniel Waddill, Jamie D. W. Thompson, James R. Neal, Simon A. Morton, James G. Tobin, Jim A. D. Matthew
Physics Faculty Research & Creative Works
A high resolution soft x-ray photoelectron spectroscopic study of Ga and as 3d core levels has been conducted for Fe/GaAs (001) as a function of Fe thickness. This work has provided unambiguous evidence of substrate disrupting chemical reactions induced by the Fe overlayer—a quantitative analysis of the acquired spectra indicates significantly differing behavior of Ga and as during Fe growth, and our observations have been compared with existing theoretical models. Our results demonstrate that the outdiffusing Ga and as remain largely confined to the interface region, forming a thin intermixed layer. Whereas at low coverages Fe has little influence on …
Random-Walk Access Times On Partially Disordered Complex Networks: An Effective Medium Theory, Julian Candia, V. M. Kenkre, Paul Ernest Parris
Random-Walk Access Times On Partially Disordered Complex Networks: An Effective Medium Theory, Julian Candia, V. M. Kenkre, Paul Ernest Parris
Physics Faculty Research & Creative Works
An analytic effective medium theory is constructed to study the mean access times for random walks on hybrid disordered structures formed by embedding complex networks into regular lattices, considering transition rates F that are different for steps across lattice bonds from the rates f across network shortcuts. The theory is developed for structures with arbitrary shortcut distributions and applied to a class of partially disordered traversal enhanced networks in which shortcuts of fixed length are distributed randomly with finite probability. Numerical simulations are found to be in excellent agreement with predictions of the effective medium theory on all aspects addressed …
Space-Based Gravitational-Wave Detectors Can Determine The Thermal History Of The Early Universe, Kazunori Nakayama, Shun Saito, Yudai Suwa, Jun'ichi Yokoyama
Space-Based Gravitational-Wave Detectors Can Determine The Thermal History Of The Early Universe, Kazunori Nakayama, Shun Saito, Yudai Suwa, Jun'ichi Yokoyama
Physics Faculty Research & Creative Works
It is shown that space-based gravitational-wave detectors such as DECIGO and/or the Big Bang Observer will provide us with invaluable information on the cosmic thermal history after inflation, and they will be able to determine the reheat temperature TR provided that it lies in the range preferred by the cosmological gravitino problem, TR ~ 105-9 GeV. Therefore it is strongly desired that they will be put into practice as soon as possible.
Ergoregion Instability Of Ultracompact Astrophysical Objects, Vitor Cardoso, Paolo Pani, Mariano Cadoni, Marco Cavaglia
Ergoregion Instability Of Ultracompact Astrophysical Objects, Vitor Cardoso, Paolo Pani, Mariano Cadoni, Marco Cavaglia
Physics Faculty Research & Creative Works
Most of the properties of black holes can be mimicked by horizonless compact objects such as gravastars and boson stars. We show that these ultracompact objects develop a strong ergoregion instability when rapidly spinning. Instability time scales can be of the order of 0.1 seconds to 1 week for objects with mass M=1-106M⊙ and angular momentum J > 0.4M2. This provides a strong indication that ultracompact objects with large rotation are black holes. Explosive events due to ergoregion instability have a well-defined gravitational-wave signature. These events could be detected by next-generation gravitational-wave detectors such as Advanced LIGO …
Double Ionization Of Helium By Ion Impact Analyzed Using Four-Body Dalitz Plots, M. F. Ciappina, Michael Schulz, T. Kirchner, Daniel Fischer, R. Moshammer, J. D. Ullrich
Double Ionization Of Helium By Ion Impact Analyzed Using Four-Body Dalitz Plots, M. F. Ciappina, Michael Schulz, T. Kirchner, Daniel Fischer, R. Moshammer, J. D. Ullrich
Physics Faculty Research & Creative Works
We have performed experimental and theoretical studies of double ionization of helium by 6 MeV proton impact using a recently developed tool, four-particle Dalitz plots [Schulz et al., J. Phys. B 22, 3091 (2007)] which enable the representation of multiple differential cross sections as a function of all four fragments in a single spectrum without loss of any part of the total cross section. As a result, the relative importance of the various interactions between the fragments can be studied in great detail. Comparisons of experimental data with theoretical first-order calculations and simulations for the higher-order (TS-2) process show that …
Theory Of Smeared Quantum Phase Transitions, Jose A. Hoyos, Thomas Vojta
Theory Of Smeared Quantum Phase Transitions, Jose A. Hoyos, Thomas Vojta
Physics Faculty Research & Creative Works
We present an analytical strong-disorder renormalization group theory of the quantum phase transition in the dissipative random transverse-field Ising chain. For Ohmic dissipation, we solve the renormalization flow equations analytically, yielding asymptotically exact results for the low-temperature properties of the system. We find that the interplay between quantum fluctuations and Ohmic dissipation destroys the quantum critical point by smearing. We also determine the phase diagram and the behavior of observables in the vicinity of the smeared quantum phase transition.
Impact Of Massive Neutrinos On The Nonlinear Matter Power Spectrum, Shun Saito, Masahiro Takada, Atsushi Taruya
Impact Of Massive Neutrinos On The Nonlinear Matter Power Spectrum, Shun Saito, Masahiro Takada, Atsushi Taruya
Physics Faculty Research & Creative Works
We present the first attempt to analytically study the nonlinear matter power spectrum for a mixed dark matter model containing neutrinos of total mass ~0.1eV, based on cosmological perturbation theory. The suppression in the power spectrum amplitudes due to massive neutrinos is enhanced in the weakly nonlinear regime. We demonstrate that, thanks to this enhanced effect, the use of such a nonlinear model may enable a precision of σ(mν,tot) ~ 0. 07eV in constraining the total neutrino mass for the planned galaxy redshift survey, a factor of 2 improvement compared to the linear regime.
Retrieval Of Electron-Atom Scattering Cross Sections From Laser-Induced Electron Rescattering Of Atomic Negative Ions In Intense Laser Fields, Xiaoxin Zhou, Zhangjin Chen, Toru Morishita, Anh-Thu Le, C. D. Lin
Retrieval Of Electron-Atom Scattering Cross Sections From Laser-Induced Electron Rescattering Of Atomic Negative Ions In Intense Laser Fields, Xiaoxin Zhou, Zhangjin Chen, Toru Morishita, Anh-Thu Le, C. D. Lin
Physics Faculty Research & Creative Works
We investigated the two-dimensional electron momentum distributions of atomic negative ions in an intense laser field by solving the time-dependent Schrödinger equation (TDSE) and using the first- and second-order strong-field approximations (SFAs). We showed that photoelectron energy spectra and low-energy photoelectron momentum distributions predicted from SFAs are in reasonable agreement with the solutions from the TDSE. More importantly, we showed that accurate electron-atom elastic scattering cross sections can be retrieved directly from high-energy electron momentum spectra of atomic negative ions in the laser field. This opens up the possibility of measuring electron-atom and electron-molecule scattering cross sections from the photodetachment …
Fundamental Constants And Tests Of Theory In Rydberg States Of Hydrogenlike Ions, Ulrich D. Jentschura, Peter J. Mohr, Joseph Tan, Benedikt J. Wundt
Fundamental Constants And Tests Of Theory In Rydberg States Of Hydrogenlike Ions, Ulrich D. Jentschura, Peter J. Mohr, Joseph Tan, Benedikt J. Wundt
Physics Faculty Research & Creative Works
A comparison of precision frequency measurements to quantum electrodynamics (QED) predictions for Rydberg states of hydrogenlike ions can yield information on values of fundamental constants and test theory. With the results of a calculation of a key QED contribution reported here, the uncertainty in the theory of the energy levels is reduced to a level where such a comparison can yield an improved value of the Rydberg constant.
Relativistic Calculation Of The Two-Photon Decay Rate Of Highly Excited Ionic States, Ulrich D. Jentschura, Andrey S. Surzhykov
Relativistic Calculation Of The Two-Photon Decay Rate Of Highly Excited Ionic States, Ulrich D. Jentschura, Andrey S. Surzhykov
Physics Faculty Research & Creative Works
Based on quantum electrodynamics, we reexamine the two-photon decay of one-electron atoms. Special attention is paid to the calculation of the (two-photon) total decay rates which can be viewed as the imaginary part of the two-loop self-energy. We argue that our approach can be easily applied to the cases with a virtual state having an intermediate energy between the initial and the final state of the decay process leading, thus, to the resonance peaks in the two-photon energy distribution. In order to illustrate our approach, we obtain fully relativistic results, resolved into electric and magnetic multipole components, for the two-photon …
Large-Angle Electron Diffraction Structure In Laser-Induced Rescattering From Rare Gases, D. Ray, B. Ulrich, I. Bocharova, C. Maharjan, P. Ranitovic, B. Gramkow, M. Magrakvelidze, S. De, I. V. Litvinyuk, Anh-Thu Le, Toru Morishita, C. D. Lin, G. G. Paulus, C. L. Cocke
Large-Angle Electron Diffraction Structure In Laser-Induced Rescattering From Rare Gases, D. Ray, B. Ulrich, I. Bocharova, C. Maharjan, P. Ranitovic, B. Gramkow, M. Magrakvelidze, S. De, I. V. Litvinyuk, Anh-Thu Le, Toru Morishita, C. D. Lin, G. G. Paulus, C. L. Cocke
Physics Faculty Research & Creative Works
We have measured full momentum images of electrons rescattered from Xe, Kr, and Ar following the liberation of the electrons from these atoms by short, intense laser pulses. At high momenta the spectra show angular structure (diffraction) which is very target dependent and in good agreement with calculated differential cross sections for the scattering of free electrons from the corresponding ionic cores.
Electron Self-Energy In The Presence Of A Magnetic Field: Hyperfine Splitting And G Factor, Vladimir A. Yerokhin, Ulrich D. Jentschura
Electron Self-Energy In The Presence Of A Magnetic Field: Hyperfine Splitting And G Factor, Vladimir A. Yerokhin, Ulrich D. Jentschura
Physics Faculty Research & Creative Works
A high-precision numerical calculation is reported for the self-energy correction to the hyperfine splitting and to the bound-electron g factor in hydrogenlike ions with low nuclear charge numbers. The binding nuclear Coulomb field is treated to all orders, and the nonperturbative remainder beyond the known Zα-expansion coefficients is determined. For the 3He+ ion, the nonperturbative remainder yields a contribution of -450Hz to the normalized difference of the 1S and 2S hyperfine-structure intervals, to be compared with the experimental uncertainty of 71 Hz and with the theoretical error of 50 Hz due to other contributions. In the case of …
Alignment Of Heavy Few-Electron Ions Following Excitation By Relativistic Coulomb Collisions, Andrey S. Surzhykov, Ulrich D. Jentschura, Th H. Stohlker, Alexandre Gumberidze, Stephan Fritzsche
Alignment Of Heavy Few-Electron Ions Following Excitation By Relativistic Coulomb Collisions, Andrey S. Surzhykov, Ulrich D. Jentschura, Th H. Stohlker, Alexandre Gumberidze, Stephan Fritzsche
Physics Faculty Research & Creative Works
The Coulomb excitation of highly charged few-electron ions in relativistic collisions with protons and low- Z atoms is studied within the framework of first-order perturbation theory and the multiconfiguration Dirac-Fock method. Apart from the computation of the total excitation cross sections, a detailed theoretical analysis has been performed for the magnetic sublevel population of the residual ions. To describe this population, general expressions are derived for the alignment parameters of the excited states of the ions, taking into account the relativistic and many-electron effects. Calculations are performed for the K→L and K→M excitation of helium- and lithiumlike uranium ions and …
Structural Evolution Of Ammonia Borane For Hydrogen Storage, Jinbo Yang, Jagat Lamsal, Qingsheng Cai, William B. Yelon, William Joseph James
Structural Evolution Of Ammonia Borane For Hydrogen Storage, Jinbo Yang, Jagat Lamsal, Qingsheng Cai, William B. Yelon, William Joseph James
Physics Faculty Research & Creative Works
We have studied the crystal structure of fully deuterated BH3NH3 using powder neutron diffraction at different temperatures. It is evident that an order-disorder phase transition occurs around 225 K. At low temperature, the compound crystallizes in the orthorhombic structure with space group Pnm21 and gradually transforms to a high temperature tetragonal structure with space group I4 mm above 225 K. At 16 K, the BD3-ND3 unit stacks along the c axis with a tilt angle of about 16° between the N-B bond and the c axis. As the temperature is increased, the BD3-ND3 groups start to reorient along the c …
Investigating Many-Electron Exchange Effects In Electron-Heavy-Atom Scattering, S. Bellm, J. Lower, Z. Stegen, Don H. Madison, H. P. Saha
Investigating Many-Electron Exchange Effects In Electron-Heavy-Atom Scattering, S. Bellm, J. Lower, Z. Stegen, Don H. Madison, H. P. Saha
Physics Faculty Research & Creative Works
In a recent publication we presented measurements and distorted-wave Born approximation (DWBA) calculations for spin asymmetries resulting from the scattering of 148 eV spin-polarized electrons from ground-state xenon atoms. While achieving reasonably good agreement between theory and experiment by accounting for many-body exchange effects through a local exchange potential, sizable discrepancies remained in some cases. It was proposed that a more sophisticated treatment of exchange might be the key to obtaining better agreement. Here we present high-precision experimental results at a lower projectile-electron energy of 112 eV. Due to improvements made to our spectrometer, these data are of significantly-improved statistical …
Discriminating Supersymmetry And Black Holes At The Cern Large Hadron Collider, Arunava Roy, Marco Cavaglia
Discriminating Supersymmetry And Black Holes At The Cern Large Hadron Collider, Arunava Roy, Marco Cavaglia
Physics Faculty Research & Creative Works
We show how to differentiate the minimal supersymmetric extension of the standard model from black hole events at the CERN Large Hadron Collider. Black holes are simulated with the CATFISH generator. Supersymmetry simulations use a combination of pythia and isajet. Our study, based on event-shape variables, visible and missing momenta, and analysis of dilepton events, demonstrates that supersymmetry and black hole events at the LHC can be easily discriminated.
Large Contribution Of Virtual Delbrück Scattering To The Emission Of Photons By Relativistic Nuclei In Nucleus-Nucleus And Electron-Nucleus Collisions, Ilya F. Ginzburg, Ulrich D. Jentschura, Valery G. Serbo
Large Contribution Of Virtual Delbrück Scattering To The Emission Of Photons By Relativistic Nuclei In Nucleus-Nucleus And Electron-Nucleus Collisions, Ilya F. Ginzburg, Ulrich D. Jentschura, Valery G. Serbo
Physics Faculty Research & Creative Works
Delbrück scattering is the elastic scattering of a photon in the Coulomb field of a nucleus via a virtual electron loop. The contribution of this virtual subprocess to the emission of a photon in the collision of ultra-relativistic nuclei, Z1Z2→Z1Z 2γ, is considered. We identify the incoming virtual photon as being generated by one of the relativistic nuclei involved in the binary collision and the scattered photon as being emitted in the process. The energy and angular distributions of the photons are calculated. The discussed process has no infrared divergence. The total cross …
Charge Exchange And X-Ray Emission Cross Sections For Multiply Charged Ions Colliding With H₂O, Sebastian Otranto, Ronald E. Olson
Charge Exchange And X-Ray Emission Cross Sections For Multiply Charged Ions Colliding With H₂O, Sebastian Otranto, Ronald E. Olson
Physics Faculty Research & Creative Works
Total and state selective nl-electron capture cross sections are presented for highly charged ions Z=4-10, 14, 18, and 26 colliding with water molecules. The energy range investigated was from 10 eV/amu (v=0.02 a.u.) to 100 keV/amu (v=2 a.u.). An initialization for the 1B1 and 3A1 orbitals of the water molecule is introduced based on the one center expansion of Moccia and compared to our previous studies based on a hydrogenic approximation within the microcanonical ensemble. The Z dependence of the calculated total cross sections is in reasonable agreement with the recent data of Mawhorter et al. [Phys. Rev. A 75, …
Potential For Ultrafast Dynamic Chemical Imaging With Few-Cycle Infrared Lasers, Toru Morishita, Anh-Thu Le, Zhangjin Chen, C. D. Lin
Potential For Ultrafast Dynamic Chemical Imaging With Few-Cycle Infrared Lasers, Toru Morishita, Anh-Thu Le, Zhangjin Chen, C. D. Lin
Physics Faculty Research & Creative Works
We studied the photoelectron spectra generated by an intense few cycle infrared laser pulse. By focusing on the angular distributions of the back rescattered high energy photoelectrons, we show that accurate differential elastic scattering cross-sections of the target ion by free electrons can be extracted. Since the incident direction and the energy of the free electrons can be easily changed by manipulating the laser's polarization, intensity and wavelength, these extracted elastic scattering cross-sections, in combination with more advanced inversion algorithms, may be used to reconstruct the effective single-scattering potential of the molecule, thus opening up the possibility of using few-cycle …
Isotope Shift In The Dielectronic Recombination Of Three-Electron ANd⁵⁷⁺, Carsten Brandau, Ch Kozhuharov, Zoltan Harman, Alfred K. Muller, Stefan Schippers, S. Kozhedub, Dietrich Bernhardt, Stefan Bohm, J. Jacobi, Eric W. Schmidt, Paul H. Mokler, Fritz J. Bosch, Heinz Jurgen Kluge, Th H. Stohlker, Klaus Beckert, P. Beller, Fritz Nolden, Markus Steck, Alexandre Gumberidze, Regina Reuschl, Uwe Spillmann, Fred John Currell, I. I. Tupitsyn, Vladimir M. Shabaev, Ulrich D. Jentschura
Isotope Shift In The Dielectronic Recombination Of Three-Electron ANd⁵⁷⁺, Carsten Brandau, Ch Kozhuharov, Zoltan Harman, Alfred K. Muller, Stefan Schippers, S. Kozhedub, Dietrich Bernhardt, Stefan Bohm, J. Jacobi, Eric W. Schmidt, Paul H. Mokler, Fritz J. Bosch, Heinz Jurgen Kluge, Th H. Stohlker, Klaus Beckert, P. Beller, Fritz Nolden, Markus Steck, Alexandre Gumberidze, Regina Reuschl, Uwe Spillmann, Fred John Currell, I. I. Tupitsyn, Vladimir M. Shabaev, Ulrich D. Jentschura
Physics Faculty Research & Creative Works
Isotope shifts in dielectronic recombination spectra were studied for Li-like ANd57+ ions with A = 142 and A = 150. From the displacement of resonance positions energy shifts δE142 150(2s-2p1/2) = 40.2(3)(6) meV [(stat)(sys)] and δE142 150(2s - 2p3/2) = 42.3(12)(20)meV of 2s - 2pj transitions were deduced. An evaluation of these values within a full QED treatment yields a change in the mean-square charge radius of 142 150δ⟨ r2⟩ = -1.36(1)(3) fm2. The approach is conceptually new and combines the advantage of a …
The Decomposition Of Yba₂Cu₃O₇₋Δ Doped Into Ba₂Yruo₆, H. A. Blackstead, William B. Yelon, M. Kornecki, M. P. Smylie, P. J. Mcginn, Jinbo Yang, Qingsheng Cai, William Joseph James
The Decomposition Of Yba₂Cu₃O₇₋Δ Doped Into Ba₂Yruo₆, H. A. Blackstead, William B. Yelon, M. Kornecki, M. P. Smylie, P. J. Mcginn, Jinbo Yang, Qingsheng Cai, William Joseph James
Physics Faculty Research & Creative Works
One of the persistent criticisms of claims for observation of superconductivity in Ba2YRu1−uCuuO6 (O6) is that the diamagnetism is actually due to the decomposition of the material into YBa2Cu3O7−delta and other phases. We report a series of experiments in which YBa2Cu3O7−delta is doped into Ba2YRuO6 and carried through a series of sintering steps which were followed by magnetization, neutron diffraction, and scanning electron microscopy/microprobe measurements. It was found that the dopant YBa2Cu3O7−delta decomposed and failed to reform with cooling. It is concluded that the O6 phase is the stable high-temperature phase. The Cu released from the Y123 decomposition doped the …
Higher-Order Contributions Observed In Three-Dimensional (E,2e) Cross-Section Measurements At 1-Kev Impact Energy, M. Dürr, C. Dimopoulou, B. Najjari, A. Dorn, K. Bartschat, I. Bray, D. V. Fursa, Zhangjin Chen, Don H. Madison, J. Ullrich
Higher-Order Contributions Observed In Three-Dimensional (E,2e) Cross-Section Measurements At 1-Kev Impact Energy, M. Dürr, C. Dimopoulou, B. Najjari, A. Dorn, K. Bartschat, I. Bray, D. V. Fursa, Zhangjin Chen, Don H. Madison, J. Ullrich
Physics Faculty Research & Creative Works
We present experimental and theoretical fully differential cross sections for single ionization by fast, 1-keV (v=8.6 a.u.) electron impact. The cross sections were measured using a momentum imaging technique for electrons and ions (reaction microscope), which covers a large fraction of the emission angles for emitted low-energy electrons (EeV) and a wide range of scattering angles. Therefore comprehensive data sets are obtained for ionizing collisions at small relative momentum and energy transfer from the projectile to the target system. The experimental data are compared with predictions from several state-of-the-art theoretical calculations. At this high impact energy the calculated cross section …
Quasiclassical Description Of Bremsstrahlung Accompanying Α Decay Including Quadrupole Radiation, Ulrich D. Jentschura, A. I. Milstein, Ivan S. Terekhov, H. Boie, Heiko Scheit, Dirk Schwalm
Quasiclassical Description Of Bremsstrahlung Accompanying Α Decay Including Quadrupole Radiation, Ulrich D. Jentschura, A. I. Milstein, Ivan S. Terekhov, H. Boie, Heiko Scheit, Dirk Schwalm
Physics Faculty Research & Creative Works
We present a quasiclassical theory of α decay accompanied by bremsstrahlung with a special emphasis on the case of 210Po, with the aim of finding a unified description that incorporates both the radiation during the tunneling through the Coulomb wall and the finite energy Eγ of the radiated photon up to Eγ~Qα | √/η, where Qα is the α-decay Q-value and η is the Sommerfeld parameter. The corrections with respect to previous quasiclassical investigations are found to be substantial, and excellent agreement with a full quantum mechanical treatment is achieved. Furthermore, we find that …
Reparameterization Invariance Of Nrqed Self-Energy Corrections And Improved Theory For Excited D States In Hydrogenlike Systems, Benedikt J. Wundt, Ulrich D. Jentschura
Reparameterization Invariance Of Nrqed Self-Energy Corrections And Improved Theory For Excited D States In Hydrogenlike Systems, Benedikt J. Wundt, Ulrich D. Jentschura
Physics Faculty Research & Creative Works
Canonically, the quantum electrodynamic radiative corrections in bound systems have been evaluated in photon energy regularization, i.e., using a noncovariant overlapping parameter that separates the high-energy relativistic scales of the virtual quanta from the nonrelativistic domain. Here, we calculate the higher-order corrections to the one-photon self-energy calculation with three different overlapping parameters (photon energy, photon mass and dimensional regularization) and demonstrate the reparameterization invariance of nonrelativistic quantum electrodynamics (NRQED) using this particular example. We also present new techniques for the calculation of the low-energy part of this correction, which lead to results for the Lamb shift of highly excited states …
Projectile Angular-Differential Cross Sections For Transfer And Transfer Excitation In Proton Collisions With Helium, M. Zapukhlyak, T. Kirchner, Ahmad Hasan, B. Tooke, Michael Schulz
Projectile Angular-Differential Cross Sections For Transfer And Transfer Excitation In Proton Collisions With Helium, M. Zapukhlyak, T. Kirchner, Ahmad Hasan, B. Tooke, Michael Schulz
Physics Faculty Research & Creative Works
Projectile angular-differential cross sections for single-transfer and transfer excitation have been calculated with the two-center extension of the nonperturbative basis generator method for 5-200 keV proton-helium collisions. The calculations are based on the independent electron model, and the eikonal approximation has been used to extract angular-differential cross sections from impact-parameter-dependent transition amplitudes. The present results are compared with experimental and previous theoretical data where available. In particular, we consider the ratio of transfer excitation to single capture versus double excitation to single excitation at intermediate energies. An experimentally observed structure in this ratio at a scattering angle about 0.5 mrad …
X-Ray Lithography Of Metal And Semiconductor Nanoparticles, Nicholas Leventis, Suchi Guha, Massimo F. Bertino, Raghuveer Reddy Gadipalli, Brian R. Heckman, John Katsoudas, Ralu Divan, Lane A. Martin, Derrick C. Mancini
X-Ray Lithography Of Metal And Semiconductor Nanoparticles, Nicholas Leventis, Suchi Guha, Massimo F. Bertino, Raghuveer Reddy Gadipalli, Brian R. Heckman, John Katsoudas, Ralu Divan, Lane A. Martin, Derrick C. Mancini
Physics Faculty Research & Creative Works
In the last few years, a considerable amount of research has focused on the three-dimensional fabrication of contacts and electronic devices. Most techniques, however, are essentially based on photoreduction, and are limited to noble- and semi-noble metals. We present here a general method that allows patterning of porous matrices in 3D with metal, but also with semiconductor nanoparticles which is of potential relevance for microfabrication applications. In our method, the pore-filling solvent of a sol-gel material is exchanged with a solution of precursors. The precursors are photodissociated and nanoparticles are formed when the monoliths are irradiated. In a series of …
Accurate Retrieval Of Structural Information From Laser-Induced Photoelectron And High-Order Harmonic Spectra By Few-Cycle Laser Pulses, Toru Morishita, Anh-Thu Le, Zhangjin Chen, C. D. Lin
Accurate Retrieval Of Structural Information From Laser-Induced Photoelectron And High-Order Harmonic Spectra By Few-Cycle Laser Pulses, Toru Morishita, Anh-Thu Le, Zhangjin Chen, C. D. Lin
Physics Faculty Research & Creative Works
By analyzing accurate theoretical results from solving the time-dependent Schrödinger equation of atoms in few-cycle laser pulses, we established the general conclusion that laser-generated high-energy electron momentum spectra and high-order harmonic spectra can be used to extract accurate differential elastic scattering and photo-recombination cross sections of the target ion with free electrons, respectively. Since both electron scattering and photoionization (the inverse of photo-recombination) are the conventional means for interrogating the structure of atoms and molecules, this result implies that existing few-cycle infrared lasers can be implemented for ultrafast imaging of transient molecules with temporal resolution of a few femtoseconds.
Dominance Of Virtual Delbrück Scattering For The Photon Emission By Nuclei In Relativistic Electron-Nucleus And Nucleus-Nucleus Collisions, Ilya F. Ginzburg, Ulrich D. Jentschura, Valery G. Serbo
Dominance Of Virtual Delbrück Scattering For The Photon Emission By Nuclei In Relativistic Electron-Nucleus And Nucleus-Nucleus Collisions, Ilya F. Ginzburg, Ulrich D. Jentschura, Valery G. Serbo
Physics Faculty Research & Creative Works
We consider the contribution of virtual Delbrück scattering to the photon emission by nuclei in the collision of two ultra-relativistic nuclei Z1 Z2 → Z1 Z2 γ and electron-nucleus collisions e Z → e Z γ, in the photon energy range m ≪ Eγ ≪ m γ, where m is the electron mass and γ is the Lorentz factor of the colliding nucleus. The discussed process has no infrared divergence. The total cross section is 50 barn for the Pb-Pb collisions at the LHC collider. The spectral distribution obtained is considerably larger than for ordinary …
Entrainment And Stimulated Emission Of Ultrasonic Piezoelectric Auto-Oscillators, Richard L. Weaver, Oleg I. Lobkis, Alexey Yamilov
Entrainment And Stimulated Emission Of Ultrasonic Piezoelectric Auto-Oscillators, Richard L. Weaver, Oleg I. Lobkis, Alexey Yamilov
Physics Faculty Research & Creative Works
Theoretical modeling and laboratory tests are conducted for nonlinear auto-oscillating piezoelectric ultrasonic devices coupled to reverberant elastic bodies. the devices are shown to exhibit behavior familiar from the theory of coupled auto-oscillators. in particular, these spontaneously emitting devices adjust their limit-cycle frequency to the spectrum of the body. It is further shown that the auto-oscillations can be entrained by an applied field; an incident wave at a frequency close to the frequency of the natural limit cycle entrains the oscillator. Special attention is paid to the phase of entrainment. Depending on details, the phase is such that the oscillator can …
Large Energy Gaps In Cac₆ From Tunneling Spectroscopy: Possible Evidence Of Strong-Coupling Superconductivity, Cihan Kurter, Lutfi Ozyuzer, Daniel Mazur, John F. Zasadzinski, Daniel Rosenmann
Large Energy Gaps In Cac₆ From Tunneling Spectroscopy: Possible Evidence Of Strong-Coupling Superconductivity, Cihan Kurter, Lutfi Ozyuzer, Daniel Mazur, John F. Zasadzinski, Daniel Rosenmann
Physics Faculty Research & Creative Works
Tunneling in CaC6 crystals reproducibly reveals superconducting gaps Δ of 2.3±0.2 meV that are ~40% larger than reported earlier. In an isotropic s -wave scenario, that puts CaC6 into the class of very strongly coupled superconductors, since 2Δ k Tc ~4.6, implying that soft Ca phonons are primarily involved in the superconductivity. This conclusion explains the relatively large Ca isotope effect found recently for CaC6, but it could also signal a strong anisotropy in the electron-phonon interaction.