13,896 research outputs found
Femtosecond probing of bimolecular reactions: The collision complex
Progress has been made in probing the femtosecond
dynamics of transition states of chemical reactions.(1) The
"half-collision" case of unimolecular reactions has been
experimentally investigated for a number of systems and
much theoretical work has already been developed.(2) For
bimolecular reactions, the case of full collision, the zero of
time is a problem which makes the femtosecond temporal
resolution of the dynamics a difficult task
Femtosecond real-time probing of reactions. VIII. The bimolecular reaction Br+I2
In this paper, we discuss the experimental technique for real-time measurement of the lifetimes of the collision complex of bimolecular reactions. An application to the atom–molecule Br+I_2 reaction at two collision energies is made. Building on our earlier Communication [J. Chem. Phys. 95, 7763 (1991)], we report on the observed transients and lifetimes for the collision complex, the nature of the transition state, and the dynamics near threshold. Classical trajectory calculations provide a framework for deriving the global nature of the reactive potential energy surface, and for discussing the real-time, scattering, and asymptotic (product-state distribution) aspects of the dynamics. These experimental and theoretical results are compared with the extensive array of kinetic, crossed beam, and theoretical studies found in the literature for halogen radical–halogen molecule exchange reactions
Method of statistical filtering
Minimal formula for bounding the cross correlation between a random forcing function and the state error when this correlation is unknown is used in optimal linear filter theory applications. Use of the bound results in overestimation of the estimation-error covariance
A study of weather-dependent data links for deep space applications
Weather-dependent data links for deep space applications, and five potential system
Ab Initio study of neutron drops with chiral Hamiltonians
We report ab initio calculations for neutron drops in a 10 MeV external
harmonic-oscillator trap using chiral nucleon-nucleon plus three-nucleon
interactions. We present total binding energies, internal energies, radii and
odd-even energy differences for neutron numbers N = 2 - 18 using the no-core
shell model with and without importance truncation. Furthermore, we present
total binding energies for N = 8, 16, 20, 28, 40, 50 obtained in a
coupled-cluster approach. Comparisons with Green's Function Monte Carlo
results, where available, using Argonne v8' with three-nucleon interactions
reveal important dependences on the chosen Hamiltonian.Comment: 7 pages, 5 figure
Stokes imaging, Doppler mapping and Roche tomography of the AM Her system V834 Cen
We report on new simultaneous phase resolved spectroscopic and polarimetric
observations of the polar (AM Herculis star) V834 Cen during a high state of
accretion. Strong emission lines and high levels of variable circular and
linear polarization are observed over the orbital period. The polarization data
is modelled using the Stokes imaging technique of Potter et al. The
spectroscopic emission lines are investigated using the Doppler tomography
technique of Marsh and Horne and the Roche tomography technique of Dhillon and
Watson. Up to now all three techniques have been used separately to investigate
the geometry and accretion dynamics in Cataclysmic Variables. For the first
time, we apply all three techniques to simultaneous data for a single system.
This allows us to compare and test each of the techniques against each other
and hence derive a better understanding of the geometry, dynamics and system
parameters of V834 Cen.Comment: 10 pages, 8 figures; Accepted for publication in MNRA
Computational studies of light acceptance and propagation in straight and curved multimodal active fibres
A Monte Carlo simulation has been performed to track light rays in
cylindrical multimode fibres by ray optics. The trapping efficiencies for skew
and meridional rays in active fibres and distributions of characteristic
quantities for all trapped light rays have been calculated. The simulation
provides new results for curved fibres, where the analytical expressions are
too complex to be solved. The light losses due to sharp bending of fibres are
presented as a function of the ratio of curvature to fibre radius and bending
angle. It is shown that a radius of curvature to fibre radius ratio of greater
than 65 results in a light loss of less than 10% with the loss occurring in a
transition region at bending angles of pi/8 rad.Comment: 21 pages, 13 figure
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