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Full-Text Articles in Physics
Thomson-Resonant Interference Effects In Elastic X-Ray Scattering Near The Cl K Edge Of Hcl, Stephane Carniato, P. Selles, Loic Journel, Renaud Guillemin, Wayne C. Stolte, L. El Khoury, T. Marin, Faris Gel'mukhanov, Dennis W. Lindle, Marc Simon
Thomson-Resonant Interference Effects In Elastic X-Ray Scattering Near The Cl K Edge Of Hcl, Stephane Carniato, P. Selles, Loic Journel, Renaud Guillemin, Wayne C. Stolte, L. El Khoury, T. Marin, Faris Gel'mukhanov, Dennis W. Lindle, Marc Simon
Chemistry and Biochemistry Faculty Research
We experimentally observed interference effects in elastic x-ray scattering from gas-phase HCl in the vicinity of the Cl K edge. Comparison to theory identifies these effects as interference effects between non-resonant elastic Thomson scattering and resonant Raman scattering. The results indicate the non-resonant Thomson and resonant Raman contributions are of comparable strength. The measurements also exhibit strong polarization dependence, allowing an easy identification of the resonant and non-resonant contributions.
Thermal Correction To The Molar Polarizability Of A Boltzmann Gas, Ulrich D. Jentschura, Mariusz Puchalski, Peter J. Mohr
Thermal Correction To The Molar Polarizability Of A Boltzmann Gas, Ulrich D. Jentschura, Mariusz Puchalski, Peter J. Mohr
Physics Faculty Research & Creative Works
Metrology in atomic physics has been crucial for a number of advanced determinations of fundamental constants. In addition to very precise frequency measurements, the molar polarizability of an atomic gas has recently also been measured very accurately. Part of the motivation for the measurements is due to ongoing efforts to redefine the International System of Units (SI), for which an accurate value of the Boltzmann constant is needed. Here we calculate the dominant shift of the molar polarizability in an atomic gas due to thermal effects. It is given by the relativistic correction to the dipole interaction, which emerges when …
Kinetic Solution Of The Structure Of A Shock Wave In A Nonreactive Gas Mixture, Eswar Josyula, Prakash Vedula, William F. Bailey, Casmir J. Suchyta Iii
Kinetic Solution Of The Structure Of A Shock Wave In A Nonreactive Gas Mixture, Eswar Josyula, Prakash Vedula, William F. Bailey, Casmir J. Suchyta Iii
Faculty Publications
The multispecies Boltzmann equation is numerically integrated to characterize the internal structure of a Mach 3 shock wave in a hard sphere gas. The collision integral is evaluated by the conservative discrete ordinate method [F. G. Tcheremissine, Comput. Math. Math. Phys. 46, 315 (2006)]. There was excellent agreement of macroscopic variables [Kosuge et al., Eur. J. Mech. B/Fluids 20, 87 (2001)]. The effect of species concentration and mass ratio on the behavior of macroscopic variables and distribution functions in the structure of the shock wave is considered for both two- and three-species gas mixtures. In a binary mixture of gases …
Classical Thermodynamics Of Particles In Harmonic Traps, Martin K. Ligare
Classical Thermodynamics Of Particles In Harmonic Traps, Martin K. Ligare
Faculty Journal Articles
No abstract provided.
Dimer-Dimer Collisions At Finite Energies In Two-Component Fermi Gases, J P. D'Incao, Seth T. Rittenhouse, Nirav P. Mehta, Chris H. Greene
Dimer-Dimer Collisions At Finite Energies In Two-Component Fermi Gases, J P. D'Incao, Seth T. Rittenhouse, Nirav P. Mehta, Chris H. Greene
Physics and Astronomy Faculty Research
We discuss a major theoretical generalization of existing techniques for handling the three-body problem that accurately describes the interactions among four fermionic atoms. Application to a two-component Fermi gas accurately determines dimer-dimer scattering parameters at finite energies and can give deeper insight into the corresponding many-body phenomena. To account for finite temperature effects, we calculate the energydependent complex dimer-dimer scattering length, which includes contributions from elastic and inelastic collisions. Our results indicate that strong finite-energy effects and dimer dissociation are crucial for understanding the physics in the strongly interacting regime for typical experimental conditions. While our results for dimer-dimer relaxation …
Rectification Of Thermal Fluctuations In Ideal Gases, Alejandro Garcia, P. Meurs, C. Van De Broeck
Rectification Of Thermal Fluctuations In Ideal Gases, Alejandro Garcia, P. Meurs, C. Van De Broeck
Faculty Publications
We calculate the systematic average speed of the adiabatic piston and a thermal Brownian motor, introduced by C. Van den Broeck, R. Kawai and P. Meurs [Phys. Rev. Lett. 93, 090601 (2004)], by an expansion of the Boltzmann equation and compare with the exact numerical solution.
Molecular Simulations Of Sound Wave Propagation In Simple Gases, Alejandro Garcia, N. Hadjiconstantinou
Molecular Simulations Of Sound Wave Propagation In Simple Gases, Alejandro Garcia, N. Hadjiconstantinou
Faculty Publications
Molecular simulations of sound waves propagating in a dilute hard sphere gas have been performed using the direct simulation Monte Carlo method. A wide range of frequencies is investigated, including very high frequencies for which the period is much shorter than the mean collision time. The simulation results are compared to experimental data and approximate solutions of the Boltzmann equation. It is shown that free molecular flow is important at distances smaller than one mean free path from the excitation point.
Observation Of Stratospheric Ozone Depletion Associated With Delta Ii Rocket Emissions, Martin N. Ross, Darin W. Toohey, W. T. Rawlins, E. C. Richard, K. K. Kelly, A. F. Tuck, M. H. Proffitt, Donald E. Hagen, Alfred R. Hopkins, Philip D. Whitefield, J. R. Benbrook, W. R. Sheldon
Observation Of Stratospheric Ozone Depletion Associated With Delta Ii Rocket Emissions, Martin N. Ross, Darin W. Toohey, W. T. Rawlins, E. C. Richard, K. K. Kelly, A. F. Tuck, M. H. Proffitt, Donald E. Hagen, Alfred R. Hopkins, Philip D. Whitefield, J. R. Benbrook, W. R. Sheldon
Physics Faculty Research & Creative Works
Ozone, chlorine monoxide, methane, and submicron particulate concentrations were measured in the stratospheric plume wake of a Delta II rocket powered by a combination of solid (NH4ClO4/Al) and liquid (LOX/kerosene) propulsion systems. We apply a simple kinetics model describing the main features of gas-phase chlorine reactions in solid propellant exhaust plumes to derive the abundance of total reactive chlorine in the plume and estimate the associated cumulative ozone loss. Measured ozone loss during two plume encounters (12 and 39 minutes after launch) exceeded the estimate by about a factor of about two. Insofar as only the …
Microscopic Simulation Of Dilute Gases With Adjustable Transport Coefficients, Alejandro Garcia, F. Baras, M. Malek Mansour
Microscopic Simulation Of Dilute Gases With Adjustable Transport Coefficients, Alejandro Garcia, F. Baras, M. Malek Mansour
Faculty Publications
The Bird algorithm is a computationally efficient method for simulating dilute gas flows. However, due to the relatively large transport coefficients at low densities, high Rayleigh or Reynolds numbers are difficult to achieve by this technique. We present a modified version of the Bird algorithm in which the relaxation processes are enhanced and the transport coefficients reduced, while preserving the correct equilibrium and nonequilibrium fluid properties. The present algorithm is found to be two to three orders of magnitude faster than molecular dynamics for simulating complex hydrodynamical flows.