Mutual Neutralization Research Articles

Treatment of asymptotic non-adiabatic couplings with higher order reprojection method in the diabatic representation.

The problem of asymptotic non-adiabatic couplings in heavy particle collisions is treated using the reprojection method. The mixing matrix that mixes the asymptotic solutions of the coupled states to obtain appropriate boundary conditions is here derived to second order, yielding a faster convergence of the cross section. In addition, the reprojection method is implemented in a diabatic representation and applied to inelastic scattering of Li + Na and H + H collisions and to mutual neutralization in H+ + H- collisions.

Dissociative recombination and resonant ion-pair formation in electron collisions with HD+

We have developed a method for which a variety of reactive scattering processes involving the H2 reaction complex can be studied using the same set of potential curves and couplings. The method is based on a close-coupling approach in a strict diabatic representation. By rigorously incorporating nonadiabatic couplings among bound states, we enable the computation of final-state distributions. Loss into the ionization continuum is accounted for with a nonlocal complex potential matrix. The method has successfully been applied in studies of H++H− mutual neutralization and H(1s)+H(ns) associative ionization. In this paper, we investigate the applicability of this method to dissociative recombination and resonant ion-pair formation in electron collisions with HD+. The importance of a nonlocal description of autoionization is demonstrated. Calculated cross sections and final-state distributions are compared with results from experiments and previous theoretical studies. Published by the American Physical Society 2024

Sprayed Oil-Water Microdroplets as a Hydrogen Source.

Liquid water provides the largest hydrogen reservoir on the earth's surface. Direct utilization of water as a source of hydrogen atoms and molecules is fundamental to the evolution of the ecosystem and industry. However, liquid water is an unfavorable electron donor for forming these hydrogen species owing to its redox inertness. We report oil-mediated electron extraction from water microdroplets, which is easily achieved by ultrasonically spraying an oil-water emulsion. Based on charge measurement and electron paramagnetic resonance spectroscopy, contact electrification between oil and a water microdroplet is demonstrated to be the origin of electron extraction from water molecules. This contact electrification results in enhanced charge separation and subsequent mutual neutralization, which enables a ∼13-fold increase of charge carriers in comparison with an ultrapure water spray, leading to a ∼16-fold increase of spray-sourced hydrogen that can hydrogenate CO2 to selectively produce CO. These findings emphasize the potential of charge separation enabled by spraying an emulsion of liquid water and a hydrophobic liquid in driving hydrogenation reactions.

Detection of negative ions in streamer discharge in air by transient cavity ringdown spectroscopy

Atmospheric-pressure discharges generated in air are expected to be electronegative, but experiments that examine negative ion densities are limited to date. In this work, we measured the temporal variation of the negative ion density in a streamer discharge generated in air. We adopted cavity ringdown spectroscopy, where negative ions were detected via weak optical absorption caused by laser photodetachment. The temporal variation of the absolute negative ion density was deduced by the transient analysis of the ringdown curve. Negative ions were detected after the disappearance of the discharge voltage and current. The negative ion density started the increase at 0.4 µs after the initiation of the discharge. The increase means the enhancement of the electron attachment frequency in the late phase of the secondary streamer with electron cooling. The survival of electrons until 0.4 µs is understood by the steep decrease in the cross section of dissociative recombination with the electron energy. The maximum negative ion density was observed at 1 µs, and it was around the noise level at 1.5 µs. The rapid decay is consistent with the destruction of negative ions by mutual neutralization with positive ions.

The mutual neutralization of hydronium and hydroxide.

Mutual neutralization of hydronium (H3O+) and hydroxide (OH-) ions is a very fundamental chemical reaction. Yet, there is only limited experimental evidence about the underlying reaction mechanisms. Here, we report three-dimensional imaging of coincident neutral products of mutual-neutralization reactions at low collision energies of cold and isolated ions in the cryogenic double electrostatic ion-beam storage ring (DESIREE). We identified predominant H2O + OH + H and 2OH + H2 product channels and attributed them to an electron-transfer mechanism, whereas a minor contribution of H2O + H2O with high internal excitation was attributed to proton transfer. The reported mechanism-resolved internal product excitation, as well as collision-energy and initial ion-temperature dependence, provide a benchmark for modeling charge-transfer mechanisms.

Mutual neutralization in collisions of Li+ with CN.

The mutual neutralization reaction in collisions of Li+ with CN- is a promising candidate for rigorous multi-dimensional ab initio studies of atom-molecule charge transfer processes. The reaction is driven by the non-adiabatic interaction between the lowest two 1A' electronic states at large Li-CN distances, resulting in a large cross section for mutual neutralization. As a first step, the relevant adiabatic potential energy surfaces and non-adiabatic interaction are computed ab initio, and the process is studied quantum mechanically using the vibrational sudden approximation, where the vibrational and rotational motions of the CN molecule are assumed to be frozen during the collision.

Agonists and Antagonists of GIP and GLP-1 Receptors: Recombinant Species-Specific Variants and Mutual Neutralization of Activity

Agonists and Antagonists of GIP and GLP-1 Receptors: Recombinant Species-Specific Variants and Mutual Neutralization of Activity

Theoretical study of inelastic processes in collisions of Y and Y+ with hydrogen atom

ABSTRACT Utilizing a simplified quantum model approach, the low-energy inelastic collision processes between yttrium atoms (ions) and hydrogen atoms have been studied. Rate coefficients corresponding to the mutual neutralization, ion-pair formation, excitation, and de-excitation processes for the above collision systems have been provided in the temperature range of 1000–10 000 K. Three ionic states and 73 covalent states are considered in calculations for the collisions of yttrium atoms with hydrogen atoms, which include six molecular symmetries and 4074 partial inelastic reaction processes. For the collisions of yttrium ions with hydrogen atoms, one ionic state and 116 covalent states are included, which are related to three molecular symmetries and 13 572 partial inelastic collision processes. It is found that the rate coefficients for the mutual neutralization process have a maximum at T = 6000 K, which is an order of magnitude higher than those of other processes. Notably, the positions of optimal windows for the collisions of yttrium atoms and ions with hydrogen atoms are found near electronic binding energy −2 eV (Y) and −4.4 eV (Y+), respectively. The scattering channels located in or near these optimal windows have intermediate-to-large rate coefficients (greater than 10−12 cm3 s−1). The reported data should be useful in the study of non-local thermodynamic equilibrium modelling.

Observation of an isotope effect in state-selective mutual neutralization of lithium with hydrogen

Observation of an isotope effect in state-selective mutual neutralization of lithium with hydrogen

Mutual neutralization in low-energy collisions of Na+ + H- ions

Abstract The low-energy mutual neutralization (MN) reactions Na+ + H- → Na(nl) + H have been studied by employing the full quantum-mechanical molecular-orbital close-coupling (QMOCC) method over a wide energy range of 10-3 to 103 eV/u. Total and state-selective cross sections have been investigated and compared with the available theoretical and experimental data, and the state-selective rate coefficients for the temperature range of 100-10000 K have been obtained. In the present work, all the necessary highly excited state are included, and the influence of rotational couplings and 10 active electrons are considered. It is found that in the energy below 10 eV/u, the Na(4s) state is the most dominant exit state with a contribution of approximately 78% to the branch fraction, which is in best agreement with the experimental data. For energies above 10 eV/u, the MN total cross section is larger than those obtained in other theoretical calculations and shows a slow decreasing trend because the main exit states change, when the energy is above 100 eV/u, the dominant exit state becomes the Na(3p) state, while the Na(4s) state becomes the third most important exit state.

Theoretical study of the I++I− mutual neutralization reaction

We have computed the cross sections of the mutual neutralization reaction between ${\mathrm{I}}^{+}$ and ${\mathrm{I}}^{\ensuremath{-}}$ for a collision energy varying from 0.001 eV to 50 eV. These cross sections were obtained using the adiabatic potential energy curves of the ${\mathrm{I}}_{2}$ system computed with a direct relativistic multireference configuration interaction method and a semiclassical approach (i.e., Landau-Zener surface hopping). We report the cross sections towards the following neutral states: $\text{I}(^{2}P_{3/2})+\text{I}{(}^{2}{P}_{3/2})$, $\text{I}{(}^{2}{P}_{3/2})+\text{I}{(}^{2}{P}_{1/2})$, $\text{I}{(}^{2}{P}_{1/2})+\text{I}{(}^{2}{P}_{1/2})$, and $\text{I}(5{p}^{4}6s)+\text{I}{(}^{2}{P}_{3/2})$. We also discuss the cross sections towards the following two excited ionic states: ${\text{I}}^{\ensuremath{-}}{(}^{1}{S}_{0})+{\text{I}}^{+}{(}^{3}{P}_{0})$ and ${\text{I}}^{\ensuremath{-}}{(}^{1}{S}_{0})+{\text{I}}^{+}{(}^{3}{D}_{2})$. The results of these calculations are in qualitative accordance with recent experimental measurements conducted in the Double ElectroStatic Ion Ring ExpEriment (DESIREE) in Stockholm. These results can be used to model iodine plasma kinetics and thus to improve our understanding of the latter.

Atomic data on inelastic processes in boron–hydrogen collisions with accounting for fine structure

ABSTRACT This paper reports the results of investigations of inelastic processes in B + H and B+ + H− collisions with accounting for the fine structure. The calculations of the cross-sections and rate coefficients for excitation, de-excitation, ion-pair formation, and mutual neutralization processes (240 in total) are performed by using the quantum asymptotic method, which is modified in this paper for accounting of the fine structure, and by the multichannel approach within the framework of the Born–Oppenheimer formalism. It is found that accounting for the fine structure may change the rate coefficients significantly, and the rates calculated with accounting for the fine structure cannot be obtained by a simple redistribution of the non-relativistic rates. The processes important for non-local thermodynamic equilibrium modelling of stellar atmospheres are designated.

Charge transfer in sodium iodide collisions.

Sodium iodide (NaI) has, over the years, served as a prototype system in studies of non-adiabatic dynamics. Here, the charge transfer collision reactions Na+ + I- ⇆ Na + I (mutual neutralization and ion-pair formation) are studied using an ab initio approach and the total and differential cross sections are calculated for the reactions. This involves electronic structure calculations on NaI to obtain adiabatic potential energy curves, non-adiabatic and spin-orbit couplings, followed by nuclear dynamics, treated fully quantum mechanically in a strictly diabatic representation. A single avoided crossing at 13.22 a0 dominates the reactions, and the total cross sections are well captured by the semi-classical Landau-Zener model. Compared to the measured ion-pair formation cross section, the calculated cross section is about a factor of two smaller, and the overall shape of the calculated differential cross section is in reasonable agreement with the measured ion-pair formation differential cross section. Treating the Landau-Zener coupling as an empirical parameter of 0.05eV, the measured total and differential cross sections are well captured when performing fully quantum mechanical cross section calculations including rotational coupling. A semi-empirical spin-orbit coupling model is also investigated, giving satisfactory estimation of the effects of spin-orbit interactions for the reactions.

Development of a resource-saving technology for the treatment of ferrum-containing wastewater from etching operations

The object of this study is wastewater from chloride and sulfate etching operations. This paper reports results of research on ways to reduce the consumption of chemical reagents in wastewater treatment systems from etching operations. Spent etching solutions are subject to regeneration with return to the production process and partial dosing to the main stream of wastewater. It was found that at a ferrum concentration of 30 g/l in etching solutions, the solution must be treated with an alkaline reagent (10–20 % NaOH) to pH=3.5–4.0 in order to return to the technological process. In this case, the final concentration of ferrum is 11 g/l. The use of hydrogen peroxide (20–40 % H2O2) together with the alkaline reagent makes it possible to increase the degree of extraction by 30 %, that is, the final concentration of ferrum is 8 g/l. When discharging 1 m3 of etching solutions, 0.5 m3 is subject to regeneration and, after mixing with 0.5 m3 of the commercial reagent (HCl) it returns to the technological process. Commercial acid consumption is reduced by 50 %. It was shown that the use of individual flows of waste solutions as a chemical reagent reduces the cost of reagents for their neutralization (saving alkaline reagent is 80 %). Thus, 1.2 kg/m3 of a commercially available reagent (NaOH) is consumed per 1 m3 of solutions (etching and degreasing) after mixing them, and, without mutual neutralization, this consumption is 6 kg/m3. To neutralize etching solutions, it is recommended to carry out the process in the range of pH=6.5–7.5. For a solution in which Fe3+ ions predominate with an initial concentration of 0.53 mol/L, a degree of extraction of 0.9 is achieved, and the total consumption of the reagent (7.1 mol/l) exceeds the stoichiometric one by only 10 %. Deep purification from ferrum-containing impurities using a magnetic device expands the possibilities of practical implementation of further desalting with inverse osmosis.

Mutual neutralization in H++H− collisions: An improved theoretical model

The total and differential cross sections of mutual neutralization in ${\mathrm{H}}^{+}+{\mathrm{H}}^{\ensuremath{-}}$ collisions are calculated ab initio and fully quantum mechanically for energies between 0.001 and 600 eV. Effects which have not previously been considered in studies on mutual neutralization (MN) for this system, such as inclusion of rotational couplings and autoionization, are investigated. Adiabatic potential curves corresponding to the relevant states of $^{1}\mathrm{\ensuremath{\Sigma}}_{g}^{+}$, $^{1}\mathrm{\ensuremath{\Sigma}}_{u}^{+}$, $^{1}\mathrm{\ensuremath{\Pi}}_{g}$ and $^{1}\mathrm{\ensuremath{\Pi}}_{u}$ symmetries as well as radial and rotational nonadiabatic couplings are computed ab initio. A quasidiabatic model is developed and applied in order to investigate the importance of higher excited states as well as the inclusion of autoionization. Molecular data for the lowest electronic resonant state in each symmetry are obtained by performing electron scattering calculations. It is shown that rotational couplings cause a significant increase of the total MN cross section while autoionization plays a minor role as a loss mechanism. Additionally, a differential cross section is obtained that is symmetric around $\ensuremath{\theta}={90}^{\ensuremath{\circ}}$. This result is in disagreement with a previous theoretical calculation where it was found that the differential cross section is dominated by backwards scattering.

Nightside 135.6 nm emission enhancements of mid/low latitudes during geomagnetic storms as observed by the ionosphere PhotoMeter (IPM) on the Chinese meteorological satellite FY-3D

IPM has detected nightside 135.6 nm emission enhancements over a wide latitude range, from the sub-auroral latitudes to the equatorial regions during geomagnetic storms. Our work, presented in this paper, uses the data of IPM to understand these 135.6 nm emission enhancements during of geomagnetic storms and studies the variations of total electron content (TEC) and the F2 layer peak electron density (NmF2) in the region of enhanced emissions. Middle and low latitude emission enhancements are presented during several medium storms in 2018. The variations of both the integrated electron content (IEC) derived from the nighttime OI 135.6 nm emission by IPM and TEC from the International GNSS Service (IGS) relative to the daily mean of magnetically quiet days of per each latitude bin (30°≦geographic latitude < 40°, 15°≦geographic latitude < 30°, 0°≦geographic latitude < 15°, −15°≦geographic latitude < 0°, −30°≦geographic latitude < -15°, −40°≦geographic latitude < -30°) are investigated and show that on magnetically storm day, IEC by IPM always increases, while TEC from IGC may increase or decrease. Even if both increase, the increase of IEC is greater than that of TEC. From the comparison of IEC and TEC during magnetic storms, it can be seen that the enhancement of the nighttime 135.6 nm emissions is not entirely due to the ionospheric change. The time of IEC enhancements at each latitude bin is in good agreement, which mainly corresponds to the main phase time of the geomagnetic storm event and lasts until the recovery phase. The available ground-based ionosonde stations provide the values of NmF2 which match the 135.6 nm emissions measured by IPM in space and time. The variations of NmF2 squared can characterize the variations of the OI 135.6 nm emissions caused by O+ ions and electrons radiative recombination. The study results show that the OI 135.6 nm emission enhancements caused by O+ ions and electrons radiative recombination (where NmF2 squared increases) are obviously a contribution to the measured 135.6 nm emission enhancements by IPM. The contribution accounts for at least one of all contributions to the measured 135.6 nm emission enhancements by IPM. However, where the NmF2 squared provided by ionosonde decrease or change little (where the OI 135.6 nm emissions cause by O+ ions and electrons radiative recombination also decrease or change little), the emission enhancements measured by IPM at storm-time appear to come from the contributions of other mechanisms, such as energetic neutral atoms precipitation, or the mutual neutralization emission (O+ + O-→2O + hʋ (135.6 nm)) which also occupies a certain proportion in 135.6 nm airglow emission at night.

Studies of mutual neutralization in collisions involving Mg+/H−, Na+/H−, Li+/H− and Li+/Cl−

The Landau-Zener model is used to systematically compute mutual neutralization cross sections for collisions between Mg+/H−, Na+/H−, Li+/H− and Li+/Cl−. Potential energy curves for electronic states that are relevant for mutual neutralization are taken from available literature. Where non-adiabatic couplings are available, they are utilized to compute the diabatic potential energy curves, crossing distance and electronic couplings. In cases where non-adiabatic couplings are not available, they are approximated using a Lorentzian function. The reaction cross sections are computed for the energy range 0.001 eV to 1000 eV. The results are compared with other available experimental and theoretical results and are found to be very comparable. There is an observable trend in the reaction cross section involving ions of metals and hydrogen at collision energies below 10 eV, with the heaviest metal showing the largest reaction cross section and the lightest metal with the lowest cross section. At collision energies below 10 eV, isotope effect is also found to have an effect on the reaction cross section for Li+/Cl−.

Biocidal Coatings from Complexes of Carboxylated Latex Particles and a Linear Cationic Polymer.

A linear polycation, poly(diallyldimethylammonium chloride), electrostatically interacts with anionic latex particles from a carboxylated butadiene-styrene copolymer in aqueous solution thus forming an interpolyelectrolyte complex. A mutual neutralization of oppositely charged latex and polycation groups occurs at W = latex/polycation = 50 w/w ratio. At W = 27, an ultimate polycation adsorption is reached, resulting in the formation of positive polycomplex particles, while at W ˂ 27, two-component systems are formed composed of positive polycomplex particles and free polycation. A film created from the W = 12 formulation shows a high toxicity to Gram-positive and Gram-negative bacteria and yeast. Repeated washing the film leads to partial removal of polycation and a 50% decrease in the activity of the film only towards Gram-negative Pseudomonas aeruginosa. The results indicate the potential for use of the mixed polymer formulations for the fabrication of antimicrobial films and coatings.

The ion–ion recombination coefficient α: comparison of temperature- and pressure-dependent parameterisations for the troposphere and stratosphere

Abstract. Many different atmospheric, physical, and chemical processes are affected by ions. An important sink for atmospheric ions is the reaction and mutual neutralisation of a positive and negative ion, also called ion–ion recombination. While the value for the ion–ion recombination coefficient α is well-known for standard conditions (namely 1.7 × 10−6 cm3 s−1), it needs to be calculated for deviating temperature and pressure conditions, especially for applications at higher altitudes of the atmosphere. In this work, we review the history of theories and parameterisations of the ion–ion recombination coefficient, focussing on the temperature and pressure dependencies as well as the altitude range between 0 and 50 km. Commencing with theories based on J. J. Thomson's work, we describe important semi-empirical adjustments as well as field, model, and laboratory data sets, followed by short reviews of binary recombination theories, model simulations, and the application of ion–aerosol theories to ion–ion recombination. We present a comparison between theories, parameterisations, and field, model, and laboratory data sets to conclude favourable parameterisations. While many theories agree well with field data above an altitude of approximately 10 km, the nature of the recombination coefficient is still widely unknown between Earth's surface and an altitude of 10 km. According to the current state of knowledge, it appears reasonable to assume an almost constant value for the recombination coefficient for this region, while it is necessary to use values that are adjusted for pressure and temperature for altitudes above 10 km. Suitable parameterisations for different altitude ranges are presented and the need for future research, be it in the laboratory or by means of modelling, is identified.

Final-state-resolved mutual neutralization in I+ - I− collisions

We have studied the mutual neutralization reaction of atomic iodine ions (i.e., ${\mathrm{I}}^{+}+{\mathrm{I}}^{\ensuremath{-}}\ensuremath{\rightarrow}\text{I}+\text{I}$) in a cryogenic double electrostatic ion-beam storage-ring apparatus. Our results show that the reaction forms iodine atoms either in the ground-state configuration ($\mathrm{I}(5{p}^{5}\phantom{\rule{0.16em}{0ex}}{}^{2}{P}^{\ensuremath{\circ}})$, \ensuremath{\sim}40%) or with one atom in an electronically excited state ($\mathrm{I}(6s{\phantom{\rule{0.16em}{0ex}}}^{2}[2]$), $\ensuremath{\sim}60%$), with no significant variation over the branching ratios in the studied collision-energy range (0.1--0.8 eV). We estimate the total charge-transfer cross section to be of the order of ${10}^{\ensuremath{-}13}\phantom{\rule{4pt}{0ex}}{\mathrm{cm}}^{2}$ at 0.1 eV collision energy. Ab initio relativistic electronic structure calculations of the potential-energy curves of ${\mathrm{I}}_{2}$ suggest that the reaction takes place at short internuclear distances. The results are discussed in view of their importance for applications in electric thrusters.