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in subjects: "Atom-Molecule Collisions"

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Algorithms and computer codes for atomic and molecular quantum scattering theory

This workshop has succeeded in bringing up 11 different coupled equation codes on the NRCC computer, testing them against a set of 24 different test problems and making them available to the user community. These codes span a wide variety of methodologies, and factors of up to 300 were observed in the spread of computer times on specific problems. A very effective method was devised for examining the performance of the individual codes in the different regions of the integration range. Many of … more

Date: January 1, 1979

Creator: Thomas, L. (ed.)

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Chemiluminescence from the reaction of Ba /sup 3/D with nitric oxide

The reaction of laser excited Ba*(/sup 3/D) states with nitric oxide is presented. BaO product is not detected, although the channel is thermodynamically open, and instead chemiluminescence is observed. Experiments which suggest that radiative recombination, Ba + NO ..-->.. BaNO* ..-->.. BaNO, is the observed reaction channel will also be presented.

Date: January 5, 1977

Creator: Johnson, S. A.; Solarz, R. W.; Dubrin, J. W. & Brotzmann, R.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Semiclassical methods for nonseparable systems

Semiclassical techniques have been widely used for describing the dynamics of molecular collisions. The calculation of discrete energy eigenvalue spectra in bound systems has also employed semiclassical methods. Work has been done toward developing semiclassical theories for rate constants in reactive systems and semiclassical eigenvalues in bound systems. Application of these theories have been made to nonseparable multidimensional systems. Transition-state theory has played an important role … more

Date: August 1, 1977

Creator: Garrett, B.C.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Interaction of rare gas metastable atoms. [Differential and total cross sections, elastic scattering, ionization, potential scattering, phase shifts, rate constants]

The physical and chemical properties of metastable rare gas atoms are discussed and summarized. This is followed by a detailed examination of the various possible pathways whereby the metastable's excess electronic energy can be dissipated. The phenomenon of chemi-ionization is given special emphasis, and a theoretical treatment based on the use of complex (optical) potential is presented. This is followed by a discussion on the unique advantages offered by elastic differential cross section me… more

Date: November 1, 1977

Creator: Wang, A.Z.F.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Reactive scattering in the bending-corrected rotating linear model

We review the theory and applications of the Bending-Corrected Rotating Linear Model (BCRLM) to problems in the quantum description of reactions between atoms and diatomic molecules. 110 refs.

Date: January 1, 1985

Creator: Walker, R.B. & Hayes, E.F.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Wavepacket theory of collisional dissociation in molecules

An explicit integration scheme is used to solve the time dependent Schroedinger equation for wavepackets which model collisions in the collinear H + H/sub 2/ system. A realistic LEPS-type potential energy surface is used. Collision energies considered are above the dissociation threshold and probabilities for collision induced dissociation are reported. Also quantum mechanical state-to-state transition probabilities are generated. These results are compared to extensive classical trajectory cal… more

Date: January 1, 1980

Creator: Kulander, K.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Crossed beam studies of full and half collisions. [F + H/sub 2/(D/sub 2/)]

Results of two experiments performed on a new very high resolution crossed molecular beams apparatus are discussed. The first experiment, photofragmentation of methyl iodide, is deconvoluted to yield vibrational state distributions for the recoiling methyl fragment. These distributions are then analyzed in terms of half-collision models and Franck-Condon factors. The second experiment, a full-collision example, is the reaction of F atoms with H/sub 2/ and D/sub 2/. Laboratory angular and veloci… more

Date: November 1, 1979

Creator: Sparks, R. K.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Caging in high energy reactions. [Role of the cage effect in hot atom reactions]

The concept of caging high energy reactions is considered. It is noted that there is no easy and unambiguous way, short of a complete and very tedious product and mechanistic analysis, which is feasible only for very few systems, to determine the contribution made by caging. It is emphasized that some products resulting from the hot reaction with a certain substrate may be formed via caging while others are not. In research on the mechanism of caging the results of Roots work on the reactions o… more

Date: 1977

Creator: Ache, Hans J.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Collisional relaxation of low lying electronically excited states of uranium: f/sup 3/ds/sup 2/(/sup 5/K/sub 5//sup 0/) and (/sup 5/L/sub 7//sup 0/)

Laser induced fluorescence techniques were used to measure the rates of electronic relaxation of atomic uranium in a beam-gas scattering apparatus. Cross sections for the collisional deactivation of the U f/sup 3/ds/sup 2/(/sup 5/K/sub 5//sup 0/) and (/sup 5/L/sub 7//sup 0/) states by H/sub 2/, D/sub 2/, HD, CH/sub 4/, N/sub 2/, and CO at room temperature are reported. Upper limits for quenching cross sections with He were also obtained. Relaxation of these uranium metastables by molecular hydr… more

Date: June 27, 1979

Creator: Chen, H. L. & Borzileri, C.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Reactive scattering of electronically excited alkali atoms with molecules

Representative families of excited alkali atom reactions have been studied using a crossed beam apparatus. For those alkali-molecule systems in which reactions are also known for ground state alkali and involve an early electron transfer step, no large differences are observed in the reactivity as Na is excited. More interesting are the reactions with hydrogen halides (HCl): it was found that adding electronic energy into Na changes the reaction mechanism. Early electron transfer is responsible… more

Date: June 1, 1987

Creator: Mestdagh, J. M.; Balko, B. A.; Covinsky, M. H.; Weiss, P. S.; Vernon, M. F.; Schmidt, H. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Crossed beam reactive scattering of oxygen atoms and surface scattering studies of gaseous condensation

A high pressure, radio frequency discharge nozzle beam source was developed for the production of very intense (greater than or equal to 10/sup 18/ atoms sr/sup -1/ sec/sup -1/) supersonic beams of oxygen atoms. This source is capable of producing seeded beams of ground state O(/sup 3/P/sub J/) atoms when dilute oxygen-argon mixtures are used, with molecular dissociation levels exceeding 80% being realized for operation at pressures up to 350 torr. When dilute oxygen-helium mixtures are employe… more

Date: September 1, 1979

Creator: Sibener, S.J.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Topics in bound-state dynamical processes: semiclassical eigenvalues, reactive scattering kernels and gas-surface scattering models

The difficulty of applying the WKB approximation to problems involving arbitrary potentials has been confronted. Recent work has produced a convenient expression for the potential correction term. However, this approach does not yield a unique correction term and hence cannot be used to construct the proper modification. An attempt is made to overcome the uniqueness difficulties by imposing a criterion which permits identification of the correct modification. Sections of this work are: semiclas… more

Date: May 1, 1979

Creator: Adams, J.E.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Vibrational energy transfer in gas phase water and ammonia

The V ..-->.. T, R relaxation rate for NH/sub 3/ (..nu../sub 2/) was studied from 198/sup 0/K to 398/sup 0/K by the method of laser-excited vibrational fluorescence. The self-deactivation rate constant decreases from 2.4 ..mu..sec torr/sup -1/ at 198/sup 0/K to 0.65 ..mu..sec/sup -1/ torr/sup -1/ at 398/sup 0/K. The rate constants for deactivation by He, Ar, N/sub 2/, and O/sub 2/ are much smaller and show a weak temperature dependence in the opposite direction. The vibrational relaxation rates… more

Date: September 1, 1979

Creator: Hovis, F.E. Jr.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Exact Monte Carlo for molecules

A brief summary of the fixed-node quantum Monte Carlo method is presented. Results obtained for binding energies, the classical barrier height for H + H2, and the singlet-triplet splitting in methylene are presented and discussed. 17 refs.

Date: March 1, 1985

Creator: Lester, W. A. Jr. & Reynolds, P. J.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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1984 Bibliography of atomic and molecular processes

This annotated bibliography includes papers on atomic and molecular processes published during 1984. Sources include scientific journals, conference proceedings, and books. Each entry is designated by one or more of the 114 categories of atomic and molecular processes used by the Controlled Fusion Atomic Data Center, Oak Ridge National Laboratory to classify data. Also indicated is whether the work was experimental or theoretical, what energy range was covered, what reactants were investigated,… more

Date: April 1, 1985

Creator: Barnett, C. F.; Gilbody, H. B.; Gregory, D. C.; Griffin, P. M.; Havener, C. C.; Howard, A. M. et al.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Molecular beam photoionization and gas-surface scattering

The energetics of the ethylene ion-molecule reactions was investigated in more detail than previously possible in two body collision experiments by photoionization of the neutral van der Waals ethylene dimer. The stability of the (C/sub 2/H/sub 4/)/sup +/C/sub 2/H/sub 4/ ion-molecule collision complex has been determined to be 18.2 +- 0.5 kcal. The highest potential barriers along the reaction coordinate for decomposition of this collision complex into C/sub 4/H/sub 7//sup +/ + H and C/sub 3/H/… more

Date: September 1, 1979

Creator: Ceyer, S.T.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Reactions of carbon atoms using crossed pulsed molecular beams

In the second year of the current funding period, we continued the study of the following reactions: C({sup 1}D) + H{sub 2} {yields} CH(X{sup 2}{Omicron}) + H, {Delta}H = {minus}6.0 kcal.mol{sup {minus}1}; C({sup 1}D) + HCl {yields} CH(X{sup 2}{Omicron}) + Cl, {Delta}H = 7.0 kcal.mol{sup {minus}1}; and C({sup 1}D) + HCl {yields} CCl(X{sup 2}{Omicron}) + H, {Delta}H = {minus}5.8 kcal.mol{sup {minus}1}. In particular, we concentrated on three issues: the use of two-photon photolysis of C{sub 3}O{… more

Date: April 1, 1990

Creator: Reisler, H.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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[Theoretical studies of combustion dynamics]

Research is reported in 3 areas: reduced dimensionality theory of atom-diatom reactions (D+H[sub 2], H+D[sub 2], Cl+HCl), reduced dimensionality theory of diatom-diatom reactions (H[sub 2]+A[sub 2][r arrow]H+HA[sub 2], H[sub 2]+CN[r arrow]H+HCN), and L[sup 2] calculations of resonances (photodetachment spectra of ClHCl[sub [minus]] and IHI[sup [minus]], H+CO system).

Date: January 1, 1990

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Coherent anti-Stokes Raman scattering (CARS) detection or hot atom reaction product internal energy distributions

Coherent anti-Stokes Raman spectroscopy (CARS) is being utilized to investigate the rovibrational energy distributions produced by reactive and nonreactive collisions of translationally hot atoms with simple molecules. Translationally hot H atoms are produced by ArF laser photolysis of HBr. Using CARS we have monitored, in a state-specific and time-resolved manner, rotational excitation of HBr (v = 0), vibrational excitation of HBr and H/sub 2/, rovibrational excitation of H/sub 2/ produced by … more

Date: January 1, 1983

Creator: Quick, C.R. Jr. & Moore, D.S.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Effects of Reagent Translational and Vibrational Energy on the Dynamics of Endothermic Reactions

The endothermic reactions Br + CH/sub 3/I ..-->.. CH/sub 3/ + IBr (..delta..H/sub 0//sup 0/ = 13 kcal/mole) and Br + CF/sub 3/I ..-->.. CF/sub 3/ + IBr (..delta..H/sub 0//sup 0/ = 11 kcal/mole) have been studied by the crossed molecular beams method. Detailed center-of-mass contour maps of the IBr product flux as a function of recoil velocity and scattering angle are derived. For both systems it is found that the IBr product is sharply backward scattered with respect to the incident Br dirction… more

Date: July 1, 1981

Creator: Krajnovich, D.; Zhang, Z.; Huisken, F.; Shen, Y.R. & Lee, Y.T.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Reactions of carbon atoms using crossed pulsed molecular beams

The development of efficient carbon atom sources was carried out concurrently with studying reactions 1--3, and we already have intriguing results concerning these reactions, even though the development phase is still in progress. Our goals are to study reactions of carbon atoms with hydrogen, hydrogen chloride, and nitrous oxide include correlations between the energy distributions of the fragments, branching ratios, and kinetic energy dependences. These studies will provide prototypical examp… more

Date: April 1, 1989

Creator: Reisler, H.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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(Laser enhanced chemical reaction studies)

Experimental studies of dynamic molecular processes are described with particular emphasis on the use of a powerful infrared diode laser probe technique developed in our laboratory. This technique allows us to determine the final states of CO{sub 2} (and other molecules) produced by collisions, photofragmentation, or chemical reactions with a spectral resolution of 0.0003 cm{sup {minus}1} and a time resolution of 10{sup {minus}7} sec. Such high spectral resolution provides a detailed picture of… more

Date: January 1, 1992

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Bibliography of atomic and molecular processes, 1983

This annotated bibliography includes papers on atomic and molecular processes published during 1983. Sources include scientific journals, conference proceedings, and books. Each entry is designated by one or more of the 114 categories of atomic and molecular processes used by the Controlled Fusion Atomic Data Center, Oak Ridge National Laboratory to classify data. Also indicated is whether the work was experimental or theoretical, what energy range was covered, what reactants were investigated,… more

Date: October 1, 1984

Creator: Barnett, C. F.; Crandall, D. H.; Gilbody, H. B.; Gregory, D. C.; Kirkpatrick, M. I.; McDaniel, E. W. et al.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Progress in vacuum-ultraviolet spectroscopy

A photoelectron spectrometer is built which analyzes for the kinetic energy of the photoionized electrons by retardation techniques. The signal to noise ratio is very high due to the use of a new lamp and increasing the aperture of the system. The resolution is found to be extremely low and the sources of difficulties are discussed and are being eliminated.

Date: June 1, 1967

Item Type: Report

Partner: UNT Libraries Government Documents Department