Ne Collisions Research Articles

Elastic scattering and rotational excitation of nitrogen molecules by sodium atoms

A quantal study of the rotational excitation of nitrogen molecules by sodium atoms is carried out. We present the two-dimensional potential energy surface of the NaN(2) complex, with the N(2) molecule treated as a rigid rotor. The interaction potential is computed using the spin unrestricted coupled-cluster method with single, double, and perturbative triple excitations (UCCSD(T)). The long-range part of the potential is constructed from the dynamic electric dipole polarizabilities of Na and N(2). The total, differential, and momentum transfer cross sections for rotationally elastic and inelastic transitions are calculated using the close-coupling approach for energies between 5 cm(-1) and 1500 cm(-1). The collisional and momentum transfer rate coefficients are calculated for temperatures between 100 K and 300 K, corresponding to the conditions under which Na-N(2) collisions occur in the mesosphere.

Strangeness production in antiproton-nucleus collisions

Antiproton annihilations on nuclei provide a very interesting way to study the behaviour of strange particles in the nuclear medium. In low energy \(\bar p\) annihilations, the hyperons are produced mostly by strangeness exchange mechanisms. Thus, hyperon production in \(\bar p A\) interactions is very sensitive to the properties of the antikaon-nucleon interaction in nuclear medium. Within the Giessen Boltzmann–Uehling–Uhlenbeck transport model (GiBUU), we analyse the experimental data on Λ and \(K^{0}_S\) production in \(\bar p A\) collisions at p lab = 0.2 − 4 GeV/c. A satisfactory overall agreement is reached, except for the \(K^{0}_S\) production in \(\bar p+{^{20}}\)Ne collisions at p lab = 608 MeV/c, where we obtain substantially larger \(K^{0}_S\) production rate. We also study the Ξ hyperon production, important in view of the forthcoming experiments at FAIR and J-PARC.

Ab Initio Based Double-Sheeted DMBE Potential Energy Surface for N3(2A″) and Exploratory Dynamics Calculations

We report a global accurate double-sheeted potential energy surface for the lowest doublet states with (2)A″ symmetry of the N(3) radical using the double many-body expansion method. The functional form ensures by construction the degeneracy of the two adiabatic sheets along the D(3h) line and the corresponding cusp behavior. Calibrated from multireference configuration interaction energies, it reproduces all the predicted stationary structures on both sheets and ensures a correct description of the dissociation limits. A test quasiclassical trajectory study of N((2)D) + N(2) collisions is also reported in the lowest adiabatic sheet of the potential energy surface. The results commend it for both classical and quantum dynamics studies, while serving as a building block for the potential energy surfaces of larger nitrogen allotropes and azides.

Luminescence measurements of Xe+ + N2 and Xe2+ + N2 hyperthermal charge transfer collisions

Luminescence spectra are recorded for collisions between Xe+/Xe2+ and molecular nitrogen at energies ranging from 4.5 to 316 eV in the center-of-mass frame. In the Xe+ + N2 collision system, evidence for luminescent charge-transfer products is only found through Xe I emission lines. The most intense features of the luminescence spectra are attributed to atomic N emissions observed above ∼20 eV. Intense ${\rm N}_{2}^{+}$N2+ A 2Πu − ${\rm X}\;^{2}\Sigma_{\rm g}^{+}$X2Σg+ and ${\rm B}\;^{2}\Sigma_{\rm u}^{+}$B2Σu+ − ${\rm X}\;^{2}\Sigma_{\rm g}^{+}$X2Σg+ radiance is observed from Xe2+ + N2 collisions. The B state formation cross section decreases with collision energy until 20 eV, after which it becomes independent of impact energy with an approximate value of 3 Å2. The cross section for ${\rm N}_{2}^{+}$N2+ A (v > 0) formation increases with energy until 20 eV, after which it remains nearly constant at ∼1 Å2. The ${\rm N}_{2}^{+}$N2+ product vibrational distributions extracted from the spectra are non-Franck-Condon for both electronic product states at low collision energies. The distributions resemble a Franck-Condon distribution at the highest energies investigated in this work.

ChemInform Abstract: The Dinitrogen‐Ligated Triaurum Cation, Aurodiazenylium, Auronitrenium, Auroammonia, and Auroammonium.

AbstractA series of Au/N binary cluster cations, [AuN4]+, [AunN2n+1]+ (n = 2—4), and [Au3N6]+ are obtained by reactive collision of N2 with laser‐vaporized gold clusters and characterized by mass spectrometry and DFT calculations at the B3LYP/DZP and B3LYP/TZP levels of theory.

重离子加速器实验环内靶控制系统

This paper describes the control system for HIRFL-CSRe internal target facility based on VAC800, VAC600 and TC hardware platform which integrates temperature control, vacuum and valve control and molecular pump control. It is able to realize remote monitor and control on temperature and vacuum and meets the requirements of physical experiments in the internal target facility. In the help of this system, Xe54+-N2 collisions experiments have been finished successfully. The whole system has been working for six months stably and safely.

ChemInform Abstract: Ne+ + C60: Collision Energy and Impact Parameter Dependence for Endohedral Complex Formation, Fragmentation, and Charge Transfer.

We report measurements of C60−2nNe+ and C+60−2n formation in collisions of Ne+ with C60 over a range from 2–212 eV (CM). Activation energies and crude angular information are given for each channel. Endohedral complex formation and fragmentation both require low impact parameter collisions, while charge transfer can occur with larger impact parameters as well.

Two Electron Transfer and Stabilization in Slow O6+ and Rare-Gas Collisions

The stabilization ratios R for double-electron transfer, i.e., the cross section ratios of true double capture to total double-electron transfer, are measured in O6+ +He, Ne and Ar collisions at 6 keV/u. A high R value about 68% is obtained for the He target, while for the Ar target, the R value is only 8%. The high R value for the He target is due to the significant direct population of the (2l, nl') configurations with high n. For the Ar target, the (quasi)symmetric configurations (3l, nl') lead to the much lower R value. Neglecting the core effects, the O6+ ion can be taken as a bare ion C6+ except the occupied 1s shell, and then the measured R values are compared with previous experimental results of C6+ projectile ions at similar impact velocity. It yields good agreement with the Ne and Ar target, while the occupied 1s shell for the O6+ +He system results in a higher R value than that in C6+ +He collisions.

CRITICAL TEST OF SIMULATIONS OF CHARGE-EXCHANGE-INDUCED X-RAY EMISSION IN THE SOLAR SYSTEM

Experimental and theoretical state-selective X-ray spectra resulting from single-electron capture in charge exchange (CX) collisions of Ne^10+ with He, Ne, and Ar are presented for a collision velocity of 933 km s^-1 (4.54 keV nucleon^-1), comparable to the highest velocity components of the fast solar wind. The experimental spectra were obtained by detecting scattered projectiles, target recoil ions, and X-rays in coincidence; with simultaneous determination of the recoil ion momenta. Use and interpretation of these spectra are free from the complications of non-coincident total X-ray measurements that do not differentiate between the primary reaction channels. The spectra offer the opportunity to test critically the ability of CX theories to describe such interactions at the quantum orbital angular momentum level of the final projectile ion. To this end, new classical trajectory Monte Carlo calculations are compared here with the measurements. The current work demonstrates that modeling of cometary, heliospheric, planetary, and laboratory X-ray emission based on approximate state-selective CX models may result in erroneous conclusions and deductions of relevant parameters.

Lie Algebraic Approach to Energy Transfer for Collinear Collision of Two Anharmonic Diatomic Molecules

An anharmonic oscillator algebra model is used to study the collinear collisions of two diatomic molecules. The transition probability for vibration-vibration energy transfer is presented. For an application of the method, we talk about the collision of N2+CO, N2+O2, and N2+N2. Through long time averaging, the transition probability changes to the function of total energy of the system. Comparing the results with the quantum results, we can see that the dynamical Lie algebraic method is useful for describing the anharmonic diatomic molecular collision.

Electronic kinetics of molecular nitrogen and molecular oxygen in high-latitude lower thermosphere and mesosphere

Abstract. Total quenching rate coefficients of Herzberg states of molecular oxygen and three triplet states of molecular nitrogen in the collisions with O2 and N2 molecules are calculated on the basis of quantum-chemical approximations. The calculated rate coefficients of electronic quenching of O2* and N2* molecules show a good agreement with available experimental data. An influence of collisional processes on vibrational populations of electronically excited N2 and O2 molecules is studied for the altitudes of high-latitude lower thermosphere and mesosphere during auroral electron precipitation. It is indicated that molecular collisions of metastable nitrogen N2(A3Σu*) with O2 molecules are principal mechanism in electronic excitation of both Herzberg states c1Σu&minus, A'3Δu, A3Σu+ and high vibrational levels of singlet states a1Δg and b1Σg+ of molecular oxygen O2 at these altitudes.

Interferences associated with electron emission from O2 by fast ions compared with H2 and N2

Oscillatory structures associated with electron emission from O2 by 3 MeV/u H2 and 1.9 MeV/u O5,82impact are analyzed and compared with results for H2 and N2. Measured molecular O2 cross sections normalized to theoretical molecular O2 cross sections indicate oscillations suggestive of second-order interferences. Contrary to previous findings for H2 targets, no evidence of first-order interferences was revealed. The results are in qualitative agreement with recent observations for 3 MeV/u H2 2 N2 collisions, where a strong suppression of the primary Young-type interferences was also reported.

State selective electron capture in slow 15N7++ He, Ne collisions studied using cold-target recoil-ion-momentum spectroscopy

Electron capture from He and Ne targets by 15N7+ has been studied at projectile velocities of 0.27 and 0.5 a.u. Cold-target recoil-ion momentum spectroscopy was used to simultaneously measure the Q-value and scattering angle. Projectile velocity and target dependence comparisons of single and double electron capture by the projectile were carried out. Single capture from both targets populates the same excited states with nearly similar angular distributions and relative populations. The populated channels in double capture from He and Ne, however, are quite different. One-step and two-step capture mechanisms are proposed for most of the populated channels in double capture.

THE IMPLANTATION AND INTERACTIONS OF O+IN TITAN'S ATMOSPHERE: LABORATORY MEASUREMENTS OF COLLISION-INDUCED DISSOCIATION OF N2AND MODELING OF POSITIVE ION FORMATION

Energetic oxygen ions are an important component of the plasma incident onto Titan's atmosphere. Therefore, we report measurements of electron capture and ionization collisions of N2 with incident O+ over the energy range 10-100 keV. Using time of flight coincidence counting techniques we also measured the collision-induced dissociation of N2 following ionization and electron capture. The electron capture and ionization cross sections were found to have comparable magnitudes. Capture collisions are dominated by non-dissociative processes with the dissociative processes providing contributions that are only slightly smaller. In contrast, ionization is entirely dominated by the dissociative processes. The energy distributions of the N+ and N atom fragments ejected by 20, 50, and 100 keV incident O+ projectiles have also been determined. These fragments carry considerable amounts of energy and if produce in the exobase region can readily escape. The cross sections measured here have been used with Cassini energetic ion and atmospheric density data to determine the ionization by and neutralization of energetic O+ penetrating Titan's N2 rich atmosphere. Neutralization by charge exchange is found not to occur efficiently above Titan's exobase, so energetic particles with large gyroradii penetrate the atmosphere primarily as ions. When the energetic O+ flux is large, we also show it is an important source of ionization and heating at depth into Titan's atmosphere and the fragments contribute to the net atmospheric loss rate.

Rotationally Inelastic Collisions of CN(A2Π) with Small Molecules

An optical-optical double resonance technique has been utilized to investigate rotational energy transfer of selected rotational/fine-structure levels of CN(A(2)Pi, v = 3) in collisions with the molecular partners CO(2) and CH(4). Total removal rate constants for several rotational/fine-structure levels were measured for both collision partners. State-to-state relative rate constants were determined for several initial levels. These show a strikingly strong collisional propensity to conserve the fine-structure/Lambda-doublet label, akin to our previous observations with the N(2) collision partner. The possible origin of this propensity is discussed.

Cross sections for single electron capture in collisions of N2+ with He at low energies

The absolute cross sections of single electron capture during the collision of N2+ with He have been measured over the energy range 0.1-300 eV/u. From the plot showing the dependence of cross sections on energy, the following three remarkable observations can be made: (1) the cross sections exhibit an oscillatory structure below 1eV/u, (2) a bend in the cross sections appears at approximately 1 eV/u and (3) there is a dip in the cross sections at approximately 70 eV/u. The formation of an oscillatory structure is attributed to the glory effect. The bend in the cross sections occurs owing to the attractive potential part of a l2n state of quasimolecule NHe2+. The dip in the cross sections appears as a result of opening a new reaction path above 70eV/u. The glory effect can be observed for the first time on a total cross section even for slow ion-neutral collisions. The objective of this study is to explore the possibilities of providing a detailed explanation of energy dependence measurements in order to study reaction dynamics for a charge changing process.

Novel Method Based on Quantum Chemistry for Calculation of Ion Induced Secondary Electron Emission Coefficient of MgO Surfaces

High ion induced secondary electron emission (IISEE) coefficient (γ) MgO protecting layers are required in order to decrease the firing voltage of plasma display panels (PDPs). Theoretical calculation of γ for MgO surfaces provides an effective way to design better protecting layers. Here, we have developed a novel γ value estimation method based on an ultra accelerated quantum chemical molecular dynamics simulation considering the collision effect of Ne+ into a flat MgO(100) surface. Compared with experimentally obtained results, our estimated γ values are only marginally different. Our study shows that γ is primarily influenced by impact sites and Ne+ acceleration voltage. To interpret the behavior of γ in terms of these two variables, we analyzed the electronic structure of the MgO surface during the collision of Ne+. Our analyses show that the work function depends on impact sites and Ne+ acceleration voltage since Ne+ interacts with the surface. Our newly developed methodology enabled γ estimation from quantum chemical instances alone, considering the effect of Ne+ collision onto the MgO surface.

State-selective differential cross section measurements for the one-electron capture processes in the F4+ - He, Ne, Ar systems at Elab = 45 eV

Using a crossed-beam apparatus, we measured systematically the relative state-selective differential cross sections for the charge-transfer processes at very low collision energy. The cross section obtained in F4+ + He system shows a peak around 0° angle, while those in F4+ + Ne and Ar collisions at the same collision energy show clear angular thresholds. The strong peak observed in F4+ + He system is interpreted as due to the glory scattering, and the cross section maximum in F4+ + Ne and Ar collisions at non-zero angles is due to the rainbow scattering.

Interference effects in electron emission spectra for 3 MeV/u H+ + O2 collisions

The present work extends the study of oscillatory structures associated with electron emission from diatomic molecular targets to 3 MeV/u H+ + O2. Electrons ejected from O2 were detected in the energy range 5 to 400 eV and for observation angles 30°, 60°, 90° and 150°. Experimental molecular O2 cross sections normalized to theoretical molecular O2 cross sections reveal oscillatory structures suggestive of secondary interferences as evidenced by their independence on the observation angle. Contrary to results for 1, 3 and 5 MeV/u H+ + H2, no obvious evidence for primary Young-type interferences was seen, a result similar to that found for H+ + N2 collisions.

The structural and electronic properties of amine-functionalized boron nitride nanotubesvia ammonia plasmas: a density functional theory study

The reaction behavior of the chemical modification of boron nitride nanotubes(BNNTs) with ammonia plasmas has been investigated by density functionaltheory (DFT) calculations. Unlike previously studied functionalization withNH3 and amino functionalgroups, we found that NH2* radicals involved in the ammonia plasmas can be covalently incorporatedto BNNTs through a strong single B–N bond. Subsequently, theH* radicals also involved in the ammonia plasmas would prefer to combine with the N atoms neighboringthe NH2-functionalized B atoms. Our study revealed that this reaction behavior can be elucidatedusing the frontier orbital theory. The calculated band structures and density of states (DOS)indicate that this modification is an effective method to modulate the electronic properties ofBNNTs. We have discussed various defects on the surface of BNNTs generated by collisions ofN2+ ions. For most defects considered, the reactivity of the functionalization of BNNTs withNH2* are enhanced. Our conclusions are independent of the chirality, and the diameterdependence of the reaction energies is presented.