The Experts below are selected from a list of 249 Experts worldwide ranked by ideXlab platform

Jonathan Tennyson - One of the best experts on this subject based on the ideXlab platform.

  • calculated cross sections for low energy Electron Collision with oh
    Plasma Sources Science and Technology, 2019
    Co-Authors: K Chakrabarti, V Laporta, Jonathan Tennyson
    Abstract:

    The hydroxyl radical, OH, is an important component of many natural and technological plasmasa#13; but there is little available information on processes involving itsa#13; Collisions with low-energy Electrons. Low-energy Electron Collisionsa#13; with OH are studied in the framework of the R-matrix method. Potentiala#13; energy curves of some of the low lying target states of doublet anda#13; quartet symmetry which go to the O($^3$P)+H($^2$S),a#13; O($^1$D)+H($^2$S) and O($^1$S)+H($^2$S) asymptotic limits area#13; obtained for inter nuclear separations between $1-6~a_0$.a#13; Scattering calculations are performed at the OH equilibrium geometrya#13; $R_e=1.8342~a_0$ to yield cross sections for elastic scattering,a#13; Electronic excitations form the $\mathrm{X}\,^2\Pi$ ground state to the firsta#13; three excited states of $\mathrm{A}\,^2\Sigma^+$, $a\,^4\Sigma^-$, $1\,^2\Sigma^-$ a#13; symmetry and for Electron impact dissociation of OH. The positions a#13; and widths for negative ion resonances in the $e$--OH system are useda#13; estimate the cross section for dissociative Electron attachment to a#13; OH which is found to be significant at Electron energies about 1.5 eV.a#13;

  • averaged Electron Collision cross sections for thermal mixtures of alpha alanine conformers in the gas phase
    Journal of Physics B, 2016
    Co-Authors: M M Fujimoto, Erik V R De Lima, Jonathan Tennyson
    Abstract:

    A theoretical study of elastic Electron Collisions with 9 conformers of the gas-phase amino acid $\alpha$-alanine (CH$_3$CH(NH$_2$)COOH) is performed. The eigenphase sums, resonance features, differential and integral cross sections are computed for each individual conformer. Resonance positions for the low-energy $\pi^*$ shape resonance are found to vary from 2.6 eV to 3.1 eV and the resonance widths from 0.3 eV to 0.5 eV. Averaged cross sections for thermal mixtures of the 9 conformers are presented. Both theoretical and experimental population ratios are considered. Thermally-averaged cross sections obtained using the best theoretical estimates give reasonable agreement with the observed thermal cross sections. Excited conformers IIA and IIB make a large contribution to this average due to their large permanent dipole moments.

  • Electron Collision with the silicon monoxide sio molecule using the r matrix method
    Journal of Physics B, 2009
    Co-Authors: Hemal N Varambhia, K. L. Baluja, Monika Gupta, A Faure, Jonathan Tennyson
    Abstract:

    SiO is a molecule that is well known astrophysically. Electron scattering calculations are presented at the static-exchange and close-coupling approximations, one including 24 target states and another including 48 states. Our study predicts the existence of several low-lying narrow 2Π, 2Δ and 2Σ− Feshbach resonances and confirms the existence of a 2Π bound state. Results from the 48-state close-coupling calculation have been employed to calculate rotational (de)excitation rates and rate-fitting coefficients, which are useful in astrophysical modelling. Ionization cross sections, rotationally summed and resolved differential and integral cross sections are also presented.

  • Electron Collision with the silicon monoxide (SiO) molecule using the R-matrix method
    J PHYS B-AT MOL OPT, 2009
    Co-Authors: Jonathan Tennyson
    Abstract:

    SiO is a molecule that is well known astrophysically. Electron scattering calculations are presented at the static-exchange and close-coupling approximations, one including 24 target states and another including 48 states. Our study predicts the existence of several low-lying narrow (2)Pi, (2)Delta and (2)Sigma(-) Feshbach resonances and confirms the existence of a (2)Pi bound state. Results from the 48-state close-coupling calculation have been employed to calculate rotational ( de) excitation rates and rate-fitting coefficients, which are useful in astrophysical modelling. Ionization cross sections, rotationally summed and resolved differential and integral cross sections are also presented.

  • Electron CollisionS WITH POLYATOMIC MOLECULES USING THE R-MATRIX METHOD
    Philosophical transactions - Royal Society. Mathematical physical and engineering sciences, 1999
    Co-Authors: Jonathan Tennyson, L A Morgan
    Abstract:

    Rmatrix theory as applied by Burke and coworkers has been outstandingly successful at treating a range of Electron Collision problems. Recently, this work has been extended to the treatment of Electron scattering from polyatomic molecules. The construction of a general ElectronpolyatomicRmatrix code is discussed. Sample results are presented for Electron Collisions with atmospherically important species nitrous oxide, ozone, water and carbon dioxide.

M.j. Kushner - One of the best experts on this subject based on the ideXlab platform.

  • Impact of Electron Collision mixing on the delay times of an Electron beam excited atomic xenon laser
    IEEE Journal of Quantum Electronics, 1990
    Co-Authors: P.j. Peters, M. Ohwa, M.j. Kushner
    Abstract:

    The atomic xenon (5d to 6p) infrared laser has been experimentally and theoretically investigated using a short-pulse (30-ns), high-power (1-10-MW/cm/sup 3/) coaxial Electron beam excitation source. In most cases, laser oscillation is not observed during the e-beam current pulse. Laser pulses of hundreds of nanoseconds duration are subsequently obtained, however, with oscillation beginning 60-800 ns after the current pulse terminates. Results from a computer model for the xenon laser reproduce the experimental values and show that oscillation begins when the fractional Electron density decays below a critical value of approximately=0.2-0.8*10/sup 6/. These results lend credence to the proposal that Electron Collision mixing of the laser levels limits the maximum value of specific power deposition that can be used to excite the atomic xenon laser efficiently on a quasi-CW basis.

  • Energy loading effects in the scaling of atomic xenon lasers
    IEEE Journal of Quantum Electronics, 1990
    Co-Authors: M. Ohwa, M.j. Kushner
    Abstract:

    The intrinsic power efficiency of the atomic xenon (5d to 6p) infrared (1.73-3.65- mu m) laser is sensitive to the rate of pumping due to Electron Collision mixing of the laser levels. Long-duration pumping at moderate power deposition may therefore result in higher energy efficiencies than pumping at higher powers. The consequences of high energy deposition (hundreds of joules per atmosphere) during long pumping pulses (hundreds of microseconds) on the intrinsic power and energy efficiency and optimum power deposition of the atomic xenon laser are examined. The dominant effect of high energy loading, gas heating, causes an increase in the Electron Collision mixing of the laser levels. The optimum power deposition for a given gas density therefore shifts to lower values with increasing gas temperature.

Yoshiharu Nakamura - One of the best experts on this subject based on the ideXlab platform.

  • Electron swarm parameters in cf3i and a set of Electron Collision cross sections for the cf3i molecule
    Journal of Physics D, 2010
    Co-Authors: Motohiro Kimura, Yoshiharu Nakamura
    Abstract:

    Electron swarm parameters (the Electron drift velocity, the longitudinal diffusion coefficient, the ionization and attachment coefficients and the effective ionization coefficient) in pure CF3I were measured in the range of E/N over 140?1000?Td. These swarm parameters were analysed using a Boltzmann equation analysis, and a set of Electron Collision cross sections for the CF3I molecule was derived so that it was consistent with the measured Electron swarm parameters in CF3I. The present set of Electron Collision cross sections of CF3I derived was used to calculate the limiting E/N values in CF3I?N2 mixtures to confirm that the results of the calculation agreed well with the recent experimental results.

  • Electron transport parameters in pure C2H2 and in C2H2-Ar mixtures and Electron Collisioncross sections of C2H2
    2008 17th International Conference on Gas Discharges and Their Applications, 2008
    Co-Authors: Yoshiharu Nakamura
    Abstract:

    We measured the drift velocity and the longitudinal diffusion coefficient of Electrons in pure C2H2. The present drift velocity in the lower E/N agreed very well with the measurement of Duncan and Walker, but there are no comparative results with our data in higher E/N range. The longitudinal diffusion coefficient of Electrons in pure C2H2 is the first measurement. We also measured these transport parameters in the 0.517 % and 5.06 % C2H2-Ar mixtures over wide E/N ranges in order to evaluate the existing set of the Electron Collision cross sections for the C2H2 molecule.

Hemal N Varambhia - One of the best experts on this subject based on the ideXlab platform.

  • Electron Collision with the silicon monoxide sio molecule using the r matrix method
    Journal of Physics B, 2009
    Co-Authors: Hemal N Varambhia, K. L. Baluja, Monika Gupta, A Faure, Jonathan Tennyson
    Abstract:

    SiO is a molecule that is well known astrophysically. Electron scattering calculations are presented at the static-exchange and close-coupling approximations, one including 24 target states and another including 48 states. Our study predicts the existence of several low-lying narrow 2Π, 2Δ and 2Σ− Feshbach resonances and confirms the existence of a 2Π bound state. Results from the 48-state close-coupling calculation have been employed to calculate rotational (de)excitation rates and rate-fitting coefficients, which are useful in astrophysical modelling. Ionization cross sections, rotationally summed and resolved differential and integral cross sections are also presented.

S Tarucha - One of the best experts on this subject based on the ideXlab platform.

  • quantum interference in Electron Collision
    Nature, 1998
    Co-Authors: Brian Odom, Yoshihisa Yamamoto, S Tarucha
    Abstract:

    The indistinguishability of identical quantum particles can lead to quantum interferences that profoundly affect their scattering1,2. If two particles collide and scatter, the process that results in the detection of the first particle in one direction and the second particle in another direction interferes quantum mechanically with the physically indistinguishable process where the roles of the particles are reversed. For bosons such as photons, a constructive interference between probability amplitudes can enhance the probability, relative to classical expectations, that both are detected in the same direction — this is known as ‘bunching’. But for fermions such as Electrons, a destructive interference should suppress this probability (‘anti-bunching’); this interference is the origin of the Pauli exclusion principle, which states that two Electrons can never occupy the same state. Although two-particle interferences have been shown for colliding photons3,4, no similar demonstration for Electrons exists2,5,6. Here we report the realization of this destructive quantum interference in the Collision of Electrons at a beam splitter. In our experiments, the quantum interference responsible for the Pauli exclusion principle is manifest as the suppression in Electron current noise after Collision.