Ternary Collisions Research Articles

Formation of Ar2+ ions in cold argon plasmas through the ternary recombination mechanism

A general scheme for calculating ternary recombination rate constants of atomic species based on a hybrid quantum–classical nonadiabatic dynamics approach is presented and applied to the specific case of the ternary recombination of atomic ions of argon in cold argon plasmas. Rate constants are reported for both fine-structure states of the Ar+ ion, 2P3/2 and 2P1/2 , T = 300 K, and for selected values of the reduced electric field. A thorough comparison with the literature data available for T = 300 K and a couple of close temperatures is performed with a favorable agreement achieved. It is shown that the excited Ar+(2P1/2) ions may contribute to the formation of dimer ions, Ar2+ , as efficiently as the ground-state ions, Ar+(2P3/2) , due to fast internal conversion of the electronic energy, which takes place in ternary collision complexes, Ar+/Ar/Ar .

Efficient SAV–Hermite methods for the nonlinear Dirac equation

We construct two SAV/CN–Hermite schemes for one and two dimensional nonlinear Dirac equation in this paper. Both SAV/CN methods preserve the energy and mass and an efficient and accurate scheme is proposed by Hermite approximation. The numerical analysis of error estimates is established on SAV/CN scheme. Numerical experiments confirm the expected convergence order. In addition, they are given to show the simulations of binary and ternary collisions.

Formation of large chunk of nuclear matter in heavy-ion collisions

In terrestrial laboratory with existing accelerators, the maximum multinucleon system produced so far is limited to that with total nucleon number being less than the sum of two colliding nuclei. Such situation may hinder our studies on the properties of nuclear many-body system. Here a way of producing large multinucleon system via multi-nucleus collision device Collider Plus in terrestrial laboratory is proposed. It is shown that large chunk of nucleonic matter can be produced through nuclear ternary fusion reactions at lower beam energies and also large block of dense matter can be formed via ternary collisions of heavy nuclei at intermediate energies. These investigations may shed lights on the studies of the synthesis of superheavy elements and the properties of bulk superdense nuclear matter.

Ozone Formation in Ternary Collisions: Theory and Experiment Reconciled.

The present Letter shows that the formation of ozone in ternary collisions O+O_{2}+M-the primary mechanism of ozone formation in the stratosphere-at temperatures below 200K (for M=Ar) proceeds through a formation of a temporary complex MO_{2}, while at temperatures above ∼700 K, the reaction proceeds mainly through a formation of long-lived vibrational resonances of O_{3}^{*}. At intermediate temperatures 200-700K, the process cannot be viewed as a two-step mechanism, often used to simplify and approximate collisions of three atoms or molecules. The developed theoretical approach is applied to the reaction O+O_{2}+Ar because of extensive experimental data available. The rate coefficients for the formation of O_{3} in ternary collisions O+O_{2}+Ar without using two-step approximations were computed for the first time as a function of collision energy. Thermally averaged coefficients were derived for temperatures 5-900K. It is found that the majority of O_{3} molecules formed initially are weakly bound. Accounting for the process of vibrational quenching of the nascent population, a good agreement with available experimental data for temperatures 100-900K is obtained.

Анализ эффективностей процессов захвата электронов ионами в ридберговские состояния и неупругих переходов n n-=SUP=--=/SUP=- в плазме смесей инертных газов

We have carried out the comparative analysis of the efficiencies of resonant and non-resonant mechanisms of electron capture by ions into Rydberg states of atoms, Xe(n), and the inelastic n → n′ transitions between the highly-excited states in the plasmas of rare gas mixtures, Rg/Xe, containing atomic, Xe$^{+}$, and molecular, RgXe$^{+}$ and Xe$_{2}^{+}$, ions (Rg = Ne, Ar and Kr, [Xe]≪[Rg]). The rate constants of resonant electron capture by Xe$^{+}$ ions in ternary collisions with rare gas atoms, Rg($^{1}S_{0}$), and dissociative recombination of heteronuclear, RgXe$^{+}$, and homonuclear, Xe$_{2}^{+}$, ions were evaluated on the basis of the original approach within the framework of the theory of non-adiabatic transitions between electronic terms of RgXe$^{+}+e$ system. For the alternative mechanism of the three-body electron capture by Xe$^{+}$ ions in collisions with Ne, Ar and Kr atoms the calculations of the rate constants were carried out in the impulse approximation by taking into account both short-range and polarization electron-atom interactions. The rate constants of the three-body electron capture by ions and n → n′ transitions in collisions with electrons were calculated on the basis of the well-known theoretical models. We have determined the ranges of plasma ionization degree and electronic and gas temperatures as well as the principal quantum number of Xe atom which correspond to situations when the resonant free-bound and bound-bound transitions of electron play a key role.

Electron capture to the Rydberg atomic states in ternary collisions with neutral particles

SynopsisWe report on the results of theoretical comparative studies of different physical mechanisms of free electron capture to the Rydberg atomic states and bound-bound transitions in discharge plasmas of Ne/Xe and Ar/Xe mixtures containing atomic and molecular ions. Particular attention is paid to the role to the resonant non-adiabatic free-bound and bound-bound transitions due to collisions with neutral particles. We show that in a wide range of low-temperature plasma parameters the contribution of resonant processes to the population of low-lying Rydberg states is predominant.

Collisional lipid exchange among DIBMA-encapsulated nanodiscs (DIBMALPs)

Copolymers of diisobutylene/maleic acid (DIBMA), styrene/maleic acid (SMA), and styrene/maleimide (SMI) solubilise membrane proteins and surrounding lipids directly from artificial and biological membranes to form polymer-bounded nanodiscs. Although they preserve a lipid-bilayer core, these nanodiscs are much more dynamic than other membrane mimics, as we have recently demonstrated for two SMA variants. Here, we used time-resolved Förster resonance energy transfer spectroscopy to quantify the kinetics and unravel the mechanisms of lipid transfer among DIBMA-encapsulated nanodiscs (DIBMALPs), with particular emphasis on the role of Coulombic repulsion, which is modulated by ionic strength and nanodisc size. Our results show that DIBMALPs exchange lipids through both binary and ternary collisions on the timescale of seconds to minutes under typical experimental conditions. By contrast, nanodiscs bounded by SMA polymers exchange lipids considerably faster through binary collisions, whereas vesicles and nanodiscs based on membrane scaffold proteins exchange lipids much more slowly through lipid monomer diffusion. As DIBMALPs are polyanionic, collisional lipid transfer is substantially accelerated by screening of Coulombic repulsion caused by increasing ionic strength or nanodisc size. Analysis of the ionic-strength dependence in terms of an extended version of the Debye–Hückel equation suggests an effective DIBMALP charge number of z = −47, which is considerably larger than that previously determined for nanodiscs bounded by more hydrophobic SMA polymers.

A standards-based approach for Auto-drawing single line diagram of multivendor smart distribution systems

This paper presents a technique for the auto-drawing of single line diagram (SLD) of multivendor distribution systems. SLDs are used in electric power system visualization, which is very important for the control and monitoring of distribution systems for fault location, identification, separation, and service restoration. The task of auto-drawing an SLD for distribution systems has been made complicated due to the introduction of distributed generations and multivendor distribution systems. This paper proposes an algorithm for auto-drawing SLD, based on a ternary tree and collision avoidance algorithm. In addition, a standards-based approach is suggested for incorporating different distribution system planned and run by different vendors. Initially, client converts the distribution system diagram to a standard model, which is then sent to the server. The server draws the SLD by using the auto-SLD drawing algorithm and sends it back to the client, which can be verified by the client.

Rotational state-dependent attachment of He atoms to cold molecular ions: An action spectroscopic scheme for rotational spectroscopy

We present a kinetics model description of a newly developed action spectroscopic method for rotational spectroscopy based on rotational state-dependent three-body attachment of He atoms to cold molecular ions stored in a cryogenic 22-pole ion trap. The model results from numerical simulations and an approximate analytical expression are compared to measurements of the J=1–0 rotational transition of CD+, for which we obtain a refined transition frequency of 453.5218509(7)GHz. From the analysis of the spectroscopic data recorded at varying experimental conditions, e.g. over a wide range of He number densities and excitation powers, we deduce that the ternary rate coefficient in the first excited rotational state of CD+ is reduced to (55±5)% of the rotational ground state value. This decrease in the rate coefficient can be rationalized as an increase of the redissociation probability in the ternary collision process. A summary of rotational spectroscopy measurements of other molecular ions using the new method will be given, and its general applicability is discussed.

Ternary drop collisions

It has been recently proposed to use drop collisions for producing advanced particles or well-defined capsules, or to perform chemical reactions where the merged drops constitute a micro-reactor. For all these promising applications, it is essential to determine whether the merged drops remain stable after the collision, forming a single entity, or if they break up. This topic, widely investigated for binary drop collisions of miscible and immiscible liquid, is quite unexplored for ternary drop collisions. The current study aims to close this gap by experimentally investigating collisions between three equal-sized drops of the same liquid arranged centri-symmetrically. Three drop generators are simultaneously operated to obtain controlled ternary drop collisions. The collision outcomes are observed via photographs and compared to those of binary collisions. Similar to binary collisions, a regime map is built, showing coalescence and bouncing as well as reflexive and stretching separation. Significant differences are observed in the transitions between these regimes.

Microscopic description of large amplitude collective motion in the nuclear astrophysics context

In the last 10 years, we have observed an important increase of interest in the application of time-dependent energy density functional (TD-EDF) theory. This approach allows to treat nuclear structure and nuclear reaction from small to large amplitude dynamics in a unified framework. The possibility to perform unrestricted three-dimensional simulations using state-of-the-art effective interactions has opened new perspectives. In the present paper, an overview of applications where the predictive power of TD-EDF has been benchmarked is given. A special emphasize is made on processes that are of astrophysical interest. Illustrations discussed here include giant resonances, fission, binary and ternary collisions leading to fusion, transfer and deep inelastic processes.

Synthesis of thin, long heavy nuclei in ternary collisions

We illustrate the formation of a thin, long structure of heavy nuclei by three-nucleus simultaneous collisions within time-dependent density functional theory. The impact parameter dependence for such a formation is systematically demonstrated through clarifications of the difference between binary and ternary collision events. A new method for producing thin, long heavy nuclei in the laboratory is suggested, as well as the possible formation of the thin, long structure in hot dense matter such as that encountered in core collapse supernovae.

Development of a Kinetic Nucleation Modelfor a Free-Expanding Argon Condensation Flow

Using classical nucleation theory (CNT), a homogeneous condensation model has been developed in previous work to simulate condensation in a free-expanding plume using the direct simulation Monte Carlo (DSMC) method. However, the accuracy of the CNT nucleation theory is questionable due to unphysical assumptions such as the use of macroscopic cluster surface tension for small clusters and the lack of an incubation time for nucleation. Molecular dynamics (MD) simulations performed in previous work confirm that the fundamental mechanism for the initiation of condensation is through dimer formation in two-stage ternary collisions of monomers. We propose a kinetic nucleation model based on the mechanism whereby stable dimers are created from triple collisions. The new hybrid MD-DSMC kinetic nucleation model is implemented in a DSMC simulation of cluster growth processes, starting from dimers, in a condensation plume

Higher-order accurate Runge-Kutta discontinuous Galerkin methods for a nonlinear Dirac model

This paper extends Runge-Kutta discontinuous Galerkin (RKDG) methods to a nonlinear Dirac (NLD) model in relativistic quantum physics, and investigates interaction dynamics of corresponding solitary wave solutions. Weak inelastic interaction in ternary collisions is first observed by using high-order accurate schemes on finer meshes. A long-lived oscillating state is formed with an approximate constant frequency in collisions of two standing waves; another is with an increasing frequency in collisions of two moving solitons. We also prove three continuum conservation laws of the NLD model and an entropy inequality, i.e. the total charge non-increasing, of the semi-discrete RKDG methods, which are demonstrated by various numerical examples.

Direct simulation of condensation in a one-dimensional unsteady expansion: Microscopic mechanisms

We apply a molecular dynamics (MD) technique to the simulation of a quasi-one-dimensional unsteady free expansion to determine the dominant microscopic mechanisms of condensation in supersonic flows. In this way, it is possible to reproduce the basic physics of the coupled condensation flow with a moderate computational effort. The MD results confirm that the fundamental mechanism for the initiation of condensation is through dimer formation in two-stage ternary collisions of monomers.

Interaction for the solitary waves of a nonlinear Dirac model

This Letter presents a numerical study of the interaction dynamics for the solitary waves of a nonlinear Dirac field with scalar self-interaction by using a fourth order accurate Runge–Kutta discontinuous Galerkin (RKDG) method. Some new interaction phenomena are observed: (a) a new quasi-stable long-lived oscillating bound state from the binary collisions of a single-humped soliton and a two-humped soliton; (b) collapse in binary and ternary collisions; (c) strongly inelastic interaction in ternary collisions; and (d) bound states with a short or long lifetime from ternary collisions.

Energy transfers in Kr–Xe mixtures following selective multiphotonic excitation of Kr(3P1). Temporal analysis in Kr–Xe mixtures

This work deals with energy transfer from the resonant state Kr(3P1) to xenon. A pulsed, brief and selective excitation of the molecular state Kr2[1u(3P1)] was achieved with a dye laser. An electrometer was used to select the appropriate excitation wavelength in order to prevent ionization. In mixtures, instead of the continuum of krypton, when a small amount of xenon was added, the first and second continua of xenon were observed, even though Kr(3P1) was initially excited, proving the efficiency of the energy transfer. From the temporal analysis in pure krypton, the three-body rate constants for Kr(3P1) and Kr(3P2) and the lifetime of the excimer Kr2[1u(3P1)] have been measured again. In the mixtures, we clearly showed the occurrence of energy transfer from Kr(3P1) to the Xe[5d(7/2)3] level, with a two-body collision rate constant of 6.8 × 105 Torr−1 s−1. A weak coupling could also intervene between these two states. The reverse collision rate constant ki was found to be about 2.9 × 103 Torr−1 s−1. The ternary heteronuclear collision rate constant of the Xe(3P2) state determined at 145 nm and 168 nm is in good agreement (38.7 Torr−2 s−1 and 36.7 Torr−2 s−1, respectively). Finally, a kinetic scheme of the main reaction processes is proposed.

Formation of argon dimers in ternary monomer collisions—A classical trajectory study

Classical trajectories are used to study formation of both stable and metastable dimers in dilute argon over a 15–500 K temperature range. The results are compared with previously published trajectory data [R. E. Howard, T. L. Planck, S. R. Trussell, B. Saadevandi, Chem. Phys. Lett. 142, 33 (1987)] and with molecular dynamics data [W. C. Schieve, and H. W. Harrison, J. Chem. Phys. 61, 700 (1974)]. There are serious differences between the results reported by Howard et al. and our trajectory data, whereas good agreement is achieved with the molecular-dynamics results reported by Schieve and Harrison. The computed recombination rate coefficients for argon are used to assess atom–atom recombination rates in other noble gases.

On the kinetic theory of rarefied gas suspensions

The system of kinetic equations for a medium of finely dispersed particles in a rarefied gas is solved by the Chapman-Enskog method. The hydrodynamic transport equations and expressions for the transport coefficients are obtained. The contribution of the three-body interactions to the transport coefficients, determining the first-order corrections in the density expansion, has been calculated for a model of hard spheres. The many-body collision contribution to the dissipative characteristics of the medium is calculated under the condition that the gas-gas collisions in the ternary and higher order collision integrals can be neglected. We also suggest a system of effective kinetic equations which take into account these effects.

Nonequilibrium processes in a polyatomic gas of moderate density in an external magnetic field

The dissipative and relaxation processes in a polyatomic gas of moderate density in an external magnetic field are considered using the methods of quantum kinetic theory. The momentum and the energy fluxes, as well as the transport coefficients; are obtained in the dissipative Navier-Stokes approximation by taking the first virial correction into account. The tensor coefficient of the shear viscosity in a gas of diamagnetic molecules is obtained as a function of the effective cross sections of binary and ternary collisions and of the value of the magnetic field. The Bloch equation for magnetization in a spatially homogeneous gas of linear diamagnetic molecules is derived. The relaxation times and the shift in the Larmor frequency due to intermolecular collisions are obtained.