Study of atomic and molecular collision phenomena by high velocity beams semiannual report, jul. 1 - dec. 31, 1967
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Amme, R. C.↗
SEARCH · Engineering Papers
Results for “atomic and molecular collisions”
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Semiempirical electric dipole moment and its derivative in H2-H2 and H2-H collisions
Semiempirical electric dipole moment and derivative in molecular-molecular and molecular-atomic collisions of hydrogen
Patch, R. W.↗
Pressure broadening and line coupling in bending bands of CO2
The pressure broadening and line coupling cross sections in the Fano-Ben Reuven theory of line shapes are calculated for bending bands of CO2 in a bath of He atoms. Molecular collision dynamics are simplified by invoking the infinite order sudden (IOS) approximation for molecular rotational and vibrational angular momentum in a manner similar to but not identical with the method developed by Clary and shown to be accurate for CO2-He. Numerical values are obtained using a pairwise additive interaction potential developed by Clary. Predictions are in good accord with data for various infrared bands and pure rotational Raman spectra. It is found that all pressure broadening and state-to-state cross sections depend on only a few dynamical factors (generalized IOS cross sections) and are therefore closely interrelated. Results are used to assess models developed previously to analyze line shapes in this and similar systems.
Green, Sheldon↗
Molecular collisions. XIV
Atom rigid rotor problem, applying generalized phase shift rotational excitation treatment in lowest approximation
Bernstein, R. B.↗
Time-of-flight experiments in molecular motion and electron-atom collision kinematics
Time-of-flight measurements for relationship between velocity, mass and temperature in molecular gas motion and electron-atom collision kinematics
Donnelly, D. P.↗
The nature of intermolecular forces.
Intermolecular forces theory, considering hydrogen atom interaction through Born- Oppenheimer approximation and variational calculations
ATOMIC COLLISION↗
Molecular collisions. XV - Classical limit of the generalized phase shift treatment of rotational excitation- Atom-rigid rotor
Rotationally inelastic molecular collisions in atom rigid rotor scattering, considering infinite order approximation of generalized phase shift treatment
Bernstein, R. B.↗
An angular momentum approximation for molecular collisions in the presence of intense laser radiation
An approximation to a previously presented rigorous description of molecular (atom-atom) collisions occurring in the presence of intense radiation is investigated. This rigorous description explicitly considers the angular momentum transferred between the molecule and the radiation field in the absorption or emission of a photon, but involves a complicated system of close-coupled equations which must be solved independently for each projection M of the initial, total molecular angular momentum. (This is a direct consequence of the lack of rotational invariance in the molecule-field problem). These equations are solved for a model system which mimics the collision of a halogen with a rare gas atom. Empirical observations made in the course of performing these calculations lead to the development of an approximation which avoids the repeated calculations for each initial M. This orientational average approximation greatly reduces the effort required to describe the system, and for the model calculation, yields accurate results for field intensities as high as 10 GW/sq cm.
Devries, P. L.↗
Potential Energy Curves and Collisions Integrals of Air Components: Interactions Involving Ionized Atoms - 2
Collision integrals are fundamental quantities required to determine the transport properties of the environment surrounding aerospace vehicles in the upper atmosphere. These collision integrals can be determined as a function of temperature from the potential energy curves describing the atomic and molecular collisions. Ab initio calculations provide a practical method of computing the required interaction potentials. In this work we will discuss recent advances in scattering calculations with an emphasis on the accuracy that is obtainable. Results for interactions of the atoms and ionized atoms of nitrogen and oxygen will be reviewed and their application to the determination of transport properties, such as diffusion and viscosity coefficients, will be examined.
Stallcop, James R.↗
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
Experiments on relativity, cosmology. atomic and molecular collision cross sections
COSMOLOGY↗
Potential energy curves and collision integrals of air components
Collision integrals are fundamental quantities required to determine the transport properties of the environment surrounding aerospace vehicles in the upper atmosphere. These collision integrals can be determined as a function of temperature from the potential energy curves describing the atomic and molecular collisions. Ab initio calculations provide a practical method of computing the required interaction potentials. In this work we will discuss recent advances with an emphasis on the accuracy that is obtainable. Results for interactions, e.g. N+N, N+O, O+O, and H+N2 will be reviewed and their application to the determination of transport properties, such as diffusion and viscosity coefficients, will be examined.
Partridge, Harry↗
Laboratory studies of atomic collision processes of importance in planetary atmospheres
Progress in the following research supported under NSG 7386 is reported: (1) measurement of differential cross sections for atomic and molecular collisions relevant to analysis and modeling of data from Pioneer 11, Pioneer 12, Voyager 1, and Voyager 2; (2) analysis of measured differential cross section results to provide scattering data in forms that are easy to apply to atmospheric modeling work; (3) analysis of the data to give basic information on the molecular potentials involved in the scattering process; and (4) development and initial use of apparatus to study dissociative processes in neutral molecules.
Stebbings, R. F.↗
Many-electron aspects of molecular promotion in ion-atom collisions - Production of core-excited states of Li in Li/+/-He collisions
Production of core-excited autoionizing states of neutral Li having configurations of the form 1snln(prime)l(prime) has been observed over the impact-energy range from 10-50 keV. Although the results for production of all such states is remarkably consistent with a quasi-molecular-excitation model proposed by Stolterfoht and Leithaeuser (1976), production of individual lines in the observed spectra exhibits collision-velocity dependencies indicative of considerably more complex processes, including processes which appear to be inherently two-electron in nature. Excitation functions are presented for (1s2s/2/)/2/S, 1s(2s2p/3/P)/2/P, 1s(2s2p/1/P)/2/P, and (1s2p/2/)/2/D core-excited state of Li and for total core excitation.
Elston, S. B.↗
Charge transfer of N sub 2 super plus and O sub 2 super plus with sodium atoms.
Molecular nitrogen and oxygen ions colliding with atomic sodium examined in crossed-beam experiment for resonance charge transfers
ATOMIC COLLISION↗
Collision spectroscopy. I.
Scaling law derived from small angle scattering theory, interpreting data in spectroscopic manner to deduce potentials and interactions between electronic states
ELECTRON STATE↗
Theoretical research - Electronic, ionic, and atomic impact phenomena Final report
Theoretical and experimental findings on atomic and molecular collisions
Smith, F. T.↗
Rotational excitation of H sub 2 and D sub 2 by H impact.
Distorted wave calculation from rotational excitation of molecular hydrogen and molecular deuterium in thermal collisions with atomic hydrogen, presenting angular distributions, cross sections, etc
HYDROGEN ATOM↗
The atom-molecule reaction D plus H2 yields HD plus H studied by molecular beams
Collisions between deuterium atoms and hydrogen molecules were studied in a modulated crossed beam experiment. The relative signal intensity and the signal phase for the product HD from reactive collisions permitted determination of both the angular distribution and HD mean velocity as a function of angle. From these a relative differential reactive scattering cross section in center-of-mass coordinates was deduced. The experiment indicates that reactively formed HD which has little or no internal excitation departs from the collision anisotropically, with maximum amplitude 180 deg from the direction of the incident D beam in center-of-mass coordinates, which shows that the D-H-H reacting configuration is short-lived compared to its rotation time. Non reactive scattering of D by H2 was used to assign absolute values to the differential reactive scattering cross sections.
Geddes, J.↗