scholarly journals Dissociative Recombination of CH+ Molecular Ion Induced by Very Low Energy Electrons

Atoms ◽  
2019 ◽  
Vol 7 (3) ◽  
pp. 82 ◽  
Author(s):  
Zsolt J. Mezei ◽  
Michel D. Epée Epée ◽  
Ousmanou Motapon ◽  
Ioan F. Schneider
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Incident Energy ◽  
Dissociative Recombination ◽  
Boltzmann Distribution ◽  
Rate Coefficients ◽  
Rotational States ◽  
Low Energy Electrons ◽  
Quantum Defect Theory ◽  
Π State

We used the multichannel quantum defect theory to compute cross sections and rate coefficients for the dissociative recombination of CH + initially in its lowest vibrational level v i + = 0 with electrons of incident energy below 0.2 eV. We have focused on the contribution of the 2 2 Π state which is the main dissociative recombination route at low collision energies. The final cross section is obtained by averaging the relevant initial rotational states ( N i + = 0 , ⋯ , 10 ) with a 300 K Boltzmann distribution. The Maxwell isotropic rate coefficients for dissociative recombination are also calculated for different initial rotational states and for electronic temperatures up to a few hundred Kelvins. Our results are compared to storage-ring measurements.

scholarly journals Quantum-state–selective electron recombination studies suggest enhanced abundance of primordial HeH+

Science ◽  
2019 ◽  
Vol 365 (6454) ◽  
pp. 676-679 ◽  
Author(s):  
Oldřich Novotný ◽  
Patrick Wilhelm ◽  
Daniel Paul ◽  
Ábel Kálosi ◽  
Sunny Saurabh ◽  
...  
Keyword(s):  
Galaxy Formation ◽  
Dissociative Recombination ◽  
Molecular Ions ◽  
Rate Coefficients ◽  
Specific Rate ◽  
Electron Recombination ◽  
Recombination Rates ◽  
Rotational States ◽  
Hydride Ion ◽  
Helium Hydride

The epoch of first star formation in the early Universe was dominated by simple atomic and molecular species consisting mainly of two elements: hydrogen and helium. Gaining insight into this constitutive era requires a thorough understanding of molecular reactivity under primordial conditions. We used a cryogenic ion storage ring combined with a merged electron beam to measure state-specific rate coefficients of dissociative recombination, a process by which electrons destroy molecular ions. We found a pronounced decrease of the electron recombination rates for the lowest rotational states of the helium hydride ion (HeH+), compared with previous measurements at room temperature. The reduced destruction of cold HeH+ translates into an enhanced abundance of this primordial molecule at redshifts of first star and galaxy formation.

scholarly journals Взаимодействие низкоэнергетических электронов с молекулами D-рибозы

2021 ◽  
Vol 129 (12) ◽  
pp. 1471
Author(s):  
И.В. Чернышова ◽  
Е.Э. Контрош ◽  
О.Б. Шпеник
Keyword(s):  
Total Cross Section ◽  
Energy Range ◽  
Cross Section ◽  
Electron Scattering ◽  
Cross Sections ◽  
Electron Attachment ◽  
Low Energy ◽  
Dissociative Electron Attachment ◽  
Low Energy Electrons ◽  
First Time

Abstract– The interactions of low-energy electrons (<20 eV) with D-ribose molecules, namely, electron scattering and dissociative attachment, are studied. The results of these studies showed that the fragmentation of D-ribose molecules occurs effectively even at an electron energy close to zero. as well as in the energy range 5.50–9.50 eV. In the total cross section of electron scattering by molecules, resonance features at energies of 5.00–9.00 eV in the region of formation of ionic fragments C3H4O2–, C2H3O2–, OH–, associated with the destruction of molecular heterocycles, were experimentally discovered for the first time. The correlation of the features observed in the scattering and dissociative electron attachment cross sections is analyzed.

Relaxation of NO+ by collision with para-H2 (j = 0)

2020 ◽  
Vol 494 (1) ◽  
pp. 129-134
Author(s):  
L D Cabrera-González ◽  
D Páez-Hernández ◽  
O Denis-Alpizar
Keyword(s):  
Cross Sections ◽  
Reproducing Kernel ◽  
Reproducing Kernel Hilbert Space ◽  
Rate Coefficients ◽  
Local Thermal Equilibrium ◽  
Large Set ◽  
Close Coupling ◽  
Rotational States ◽  
Scaling Procedure ◽  
Collisional Rate Coefficients

ABSTRACT The first tentative detection of the nitrosylium ion (NO+) in the interstellar medium (ISM) was reported just a few years ago. The application of non-local thermal equilibrium models requires the knowledge of the collisional rate coefficients with the most common colliders in the ISM (e.g. He, H, H2, and e). The main goals of this paper are to study the collision of the NO+ molecule with para-H2 (j = 0) and report the rate coefficients for the lower rotational states of NO+. A large set of ab initio energies was computed at the CCSD(T)/aug-cc-pV5Z level of theory. A new potential energy surface averaged over the H2 orientations was then fitted using a reproducing kernel Hilbert space procedure. The state-to-state cross-sections of NO++para-H2 (j = 0) for the first 18 rotational levels were computed using the close-coupling method. The rotational rate coefficients of this system were compared with those for NO++He, and a different propensity rule was found. Furthermore, the hyperfine rate coefficients were also calculated using the infinite-order-sudden scaling procedure.

scholarly journals Rotational relaxation of HCO+ and DCO+ by collision with H2

2020 ◽  
Vol 497 (4) ◽  
pp. 4276-4281 ◽  
Author(s):  
Otoniel Denis-Alpizar ◽  
Thierry Stoecklin ◽  
Anne Dutrey ◽  
Stéphane Guilloteau
Keyword(s):  
Cross Sections ◽  
Rate Coefficients ◽  
Local Thermal Equilibrium ◽  
Rotational Relaxation ◽  
Close Coupling ◽  
Excitation Rate ◽  
Rotational States ◽  
Non Local ◽  
The Difference ◽  
Isotopic Effects

ABSTRACT The HCO+ and DCO+ molecules are commonly used as tracers in the interstellar medium. Therefore, accurate rotational rate coefficients of these systems with He and H2 are crucial in non-local thermal equilibrium models. We determine in this work the rotational de-excitation rate coefficients of HCO+ in collision with both para- and ortho-H2, and also analyse the isotopic effects by studying the case of DCO+. A new four-dimensional potential energy surface from ab initio calculations was developed for the HCO+–H2 system, and adapted to the DCO+–H2 case. These surfaces are then employed in close-coupling calculations to determine the rotational de-excitation cross-sections and rate coefficients for the lower rotational states of HCO+ and DCO+. The new rate coefficients for HCO+ + para-H2 were compared with the available data, and a set of rate coefficients for HCO+ + ortho-H2 is also reported. The difference between the collision rates with ortho- and para-H2 is found to be small. These calculations confirm that the use of the rate coefficients for HCO+ + para-H2 for estimating those for HCO+ + ortho-H2 as well as for DCO+ + para-H2 is a good approximation.

scholarly journals Quantemol Electron Collisions (QEC): An Enhanced Expert System for Performing Electron Molecule Collision Calculations Using the R-Matrix Method

Atoms ◽  
2019 ◽  
Vol 7 (4) ◽  
pp. 97 ◽  
Author(s):  
Bridgette Cooper ◽  
Maria Tudorovskaya ◽  
Sebastian Mohr ◽  
Aran O’Hare ◽  
Martin Hanicinec ◽  
...  
Keyword(s):  
Expert System ◽  
Cross Sections ◽  
Electron Attachment ◽  
Dissociative Recombination ◽  
Biological Tissues ◽  
Reaction Rates ◽  
High Energy ◽  
Electron Collision ◽  
Low Energy Electrons ◽  
Ionization Cross Sections

Collisions of low energy electrons with molecules are important for understanding many aspects of the environment and technologies. Understanding the processes that occur in these types of collisions can give insights into plasma etching processes, edge effects in fusion plasmas, radiation damage to biological tissues and more. A radical update of the previous expert system for computing observables relevant to these processes, Quantemol-N, is presented. The new Quantemol Electron Collision (QEC) expert system simplifyies the user experience, improving reliability and implements new features. The QEC graphical user interface (GUI) interfaces the Molpro quantum chemistry package for molecular target setups, and the sophisticated UKRmol+ codes to generate accurate and reliable cross-sections. These include elastic cross-sections, super elastic cross-sections between excited states, electron impact dissociation, scattering reaction rates, dissociative electron attachment, differential cross-sections, momentum transfer cross-sections, ionization cross sections, and high energy electron scattering cross-sections. With this new interface we will be implementing dissociative recombination estimations, vibrational excitations for neutrals and ions, and effective core potentials in the near future.

Quantum and Quasiclassical Dynamics of the ${\rm\bf C}(\bf ^3P)$ + ${\rm\bf H_2}(\bf ^1\Sigma_g^+)$ $\rightarrow$ ${\rm\bf H}(\bf ^2S)$ + ${\rm\bf CH}(\bf ^2\Pi)$ reaction: Coriolis Coupling Effects and Stereodynamics

2021 ◽  
Author(s):  
Dong Liu ◽  
Lulu Zhang ◽  
Juan Zhao ◽  
Qin Zhang ◽  
Yuzhi Song ◽  
...  
Keyword(s):  
Angular Momentum ◽  
Wave Packet ◽  
Cross Section ◽  
Cross Sections ◽  
Rate Coefficients ◽  
Quantum Mechanical ◽  
Coriolis Coupling ◽  
Coupling Effects ◽  
Mechanical Wave ◽  
Quantum Mechanical Wave Packet

Abstract The dynamics of ${\rm\bf C}$ + ${\rm\bf H_2}$ $\rightarrow$ ${\rm\bf H}$ + ${\rm\bf CH}$ reaction is theoretically studied using the quasiclassical trajectory and quantum mechanical wave packet methods. The analysis of reaction probabilities, integral cross sections and rate coefficients reveal the essential coriolis coupling effects in the quantum mechanical wave packet calculations. The calculated polarization-dependent differential cross section, P($\theta_r$) and P($\phi_r$) show that the $\bf j'$ of product rotational angular momentum is not only aligned along the y-axis and the direction of the vector $\bf x+z$, but also strongly oriented along the positive y-axis.

scholarly journals Second Born fully differential cross sections for direct ionization of H(1s) by proton and antiproton collisions

2015 ◽  
Vol 93 (12) ◽  
pp. 1495-1500 ◽  
Author(s):  
Reda S. Tantawi
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Differential Cross ◽  
Incident Energy ◽  
Significant Contribution ◽  
Born Term ◽  
Differential Cross Sections ◽  
Direct Ionization ◽  
Fully Differential ◽  
Impact Energies

Fully differential cross sections for ionization of H(1s) atoms by collision with protons and antiprotons are calculated within the second-order Born closure approximation. The calculations are performed for emission of electrons with different energies into planes, moving from the scattering to the perpendicular planes at different impact energies and small scattering angles from which a significant contribution to the total cross section comes. The influence of the projectile’s charge and the second Born term on the calculations varies according to the incident energy, emission energy, and the scattering angle.

scholarly journals Low Energy Electron Scattering From H2

1990 ◽  
Vol 43 (5) ◽  
pp. 665 ◽  
Author(s):  
MJ Brunger ◽  
Stephen J Buckman ◽  
DS Newman
Keyword(s):  
Cross Section ◽  
Electron Scattering ◽  
Cross Sections ◽  
Incident Energy ◽  
Vibrational Excitation ◽  
Elastic Electron Scattering ◽  
Total Cross Sections ◽  
Threshold Excitation ◽  
Low Energy Electron ◽  
Good Agreement

Absolute differential and integrated total cross sections for elastic electron scattering and vibrational excitation of molecular hydrogen have been measured at an incident energy of 1�5 eV. The results are presented and discussed with particular reference to a long-standing impasse which has existed between and within experiment and theory for the near-threshold excitation of the first vibrational state of H2. The integral vibrational cross section is in good agreement (�10%) with previous beam experiments and theory but is some 60% higher than the cross section derived from a swarm analysis.

scholarly journals Quantemol Electron Collisions (QEC): An Enhanced Expert System for Performing Electron Molecule Collision Calculations Using the R-matrix Method

2019 ◽  
Author(s):  
Bridgette Cooper ◽  
Maria Tudorovskaya ◽  
Sebastian Mohr ◽  
Aran O'Hare ◽  
Martin Hanicinec ◽  
...  
Keyword(s):  
Expert System ◽  
Cross Sections ◽  
Electron Attachment ◽  
Dissociative Recombination ◽  
Biological Tissues ◽  
Reaction Rates ◽  
High Energy ◽  
Electron Collision ◽  
Low Energy Electrons ◽  
Ionization Cross Sections

Collisions of low energy electrons with molecules are important for understanding many aspects of the environment and technologies. Understanding the processes that occur in these types of collisions can give insights into plasma etching processes, edge effects in fusion plasmas, radiation damage to biological tissues and more. A radical update of the previous expert system for computing observables relevant to these processes, Quantemol-N, is presented. The new Quantemol Electron Collision (QEC) expert system simplifyies the user experience, improving reliability and implements new features. The QEC GUI interfaces the Molpro quantum chemistry package for molecular target setups and to the sophisticated UKRmol+ codes to generate accurate and reliable cross-sections. These include elastic cross-sections, super elastic cross-sections between excited states, electron impact dissociation, scattering reaction rates, dissociative electron attachment, differential cross-sections, momentum transfer cross-sections, ionization cross sections and high energy electron scattering cross-sections. With this new interface we will be implementing dissociative recombination estimations, vibrational excitations for neutrals and ions, and effective core potentials in the near future.

scholarly journals Elastic scattering of low-energy electrons by OCS molecules.

2000 ◽  
Vol 53 (3) ◽  
pp. 399 ◽  
Author(s):  
M. H. F. Bettega ◽  
M. A. P. Lima ◽  
L. G. Ferreira
Keyword(s):  
Experimental Data ◽  
Cross Section ◽  
Electron Scattering ◽  
Cross Sections ◽  
Ab Initio Calculation ◽  
Low Energy ◽  
Low Energy Electrons ◽  
Exchange Approximation ◽  
Low Energy Electron ◽  
Theoretical Results

We report results from an ab initio calculation of low-energy electron scattering by OCS molecules. We used the Schwinger multichannel method with pseudopotentials at the fixed-nuclei static-exchange approximation to calculate elastic integral, differential and momentum transfer cross sections in the energy range from 5 to 50 eV. We compare our results with available theoretical results and experimental data. Through the symmetry decomposition of our integral cross section and eigenphase sum analysis, we found structures in the cross sections that may be interpreted as shape resonances for ∑, ∏ and Δ symmetries. We compared the results for OCS with our previous results on the e––CS2 collision. In particular, we found a similar behaviour in the shape of the symmetry decomposed cross sections of OCS and of CS2 when, for the latter, we sum over the ‘g’ and ‘u’ contributions.

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