Electron Scattering Cross Sections Research Articles

Electron scattering study on acetic acid and methyl formate

Abstract In this work we report the results of a theoretical calculation of the elastic, differential scattering, and excitation cross-sections on electron interactions with the C2H4O2 isomers (methyl formate and acetic acid) using the ab initio R-matrix method in the energy range of 0.1-20 eV. The computations were performed using static exchange (SE), static exchange plus polarization (SEP) and Close-Coupling (CC) models with electronic structure calculation for these molecules performed using GAMESS. In the electron scattering cross section we have identified π* type resonance in both the isomers. Ionization cross-sections for both the molecules from ionization threshold to 500 eV using BEB method are also presented here. We endeavoured to explore the isomeric effect on various cross sections among these two isomers and included the third isomer, namely glycolaldehyde, as reported in our previous publication.

Empirical fits to inclusive electron-carbon scattering data obtained by deep-learning methods

Employing the neural network framework, we obtain empirical fits to the electron-scattering cross sections for carbon over a broad kinematic region, extending from the quasielastic peak through resonance excitation to the onset of deep-inelastic scattering. We consider two different methods of obtaining such model-independent parametrizations and the corresponding uncertainties: based on the bootstrap approach and the Monte Carlo dropout approach. In our analysis, the χ2 defines the loss function, including point-to-point and normalization uncertainties for each independent set of measurements. Our statistical approaches lead to fits of comparable quality and similar uncertainties of the order of 7%. To test these models, we compare their predictions to test datasets excluded from the training process and theoretical predictions obtained within the spectral function approach. The predictions of both models agree with experimental measurements and theoretical calculations. We also perform a comparison to a dataset lying beyond the covered kinematic region, and find that the bootstrap approach shows better interpolation and extrapolation abilities than the one based on the dropout algorithm. Published by the American Physical Society 2024

Low energy electron scattering cross sections of cyanotriacetylene (HC7N) based on ab-initio R-matrix method

Cyanotriacetylene (HC7N) is a linear unsaturated molecule detected in various regions of space. In this present study, we explored the quantum dynamics of low-energy electron collisions with linear cyanopolyyne molecule (HC7N) to identify the locations and structural features of their metastable negative ions (also known as transient negative ions). We employed the R-matrix method for handling low-energy electron scattering studies. To uncover trends among cyanopolyynes molecules, we have also incorporated results from Cyanoacetylene (HC3N) and Cyanodiacetylene (HC5N). Notably, we observed that the number of π* resonances increases and shifts to lower energies as the number of triple bonds increases in higher-order molecules. Our theoretical calculations contain elastic, differential, and momentum cross-sections in the elastic part. Additionally, we calculated excitation and ionization cross-sections in the inelastic regime. This comprehensive theoretical data on electron scattering will be valuable for understanding the molecular chemistry involving this interesting molecule.

Elastic cross section data for precursor molecules used in low-temperature plasmas: Sn(CH3)4 and Ga(CH3)3

Tetramethyltin [Sn(CH3)4] and trimethylgallium [Ga(CH3)3] are important source molecules of Sn and Ga atoms which are used in manufacturing techniques involving low-temperature plasmas. Accurate numerical modeling of plasma environments requires a comprehensive set of electron scattering cross sections by these precursor molecules. Here, we report the elastic integral, differential, and momentum transfer cross sections for electron collisions with Sn(CH3)4 and Ga(CH3)3 for energies ranging from 0 to 30 eV. Our calculations were carried out with the Schwinger multichannel method implemented with pseudopotentials and considered two levels of approximation in our calculations, namely static-exchange and static-exchange plus polarization. We identified three shape resonances for Sn(CH3)4 and one clear low-lying resonance for Ga(CH3)3. The low-energy behavior of the s-wave cross section and eigenphase was investigated and, for both molecules, we found evidence of a Ramsauer–Townsend (RT) minimum and a virtual state. Our results indicate that negative differential conductivity would occur in a gas composed of Sn(CH3)4. On the other hand, this effect would be suppressed in a gas of Ga(CH3)3 due to an overlap between the position of the RT minimum and the shape resonance in the momentum-transfer cross section.

Integral Electron Scattering Cross Sections from N2O for Impact Energies Ranging from 1 to 1000 eV.

Accurate total cross sections (TCS), within 5%, for electron scattering by N2O molecules have been measured with a magnetically confined electron transmission apparatus for impact energies ranging from 1 to 200 eV. For higher energies, these measurements have been complemented with our independent atom-based screening corrected additivity rule, including interference (IAM-SCAR + I) method to determine a complete reference TCS data set in the energy range (1-1000 eV). After a critical discussion that includes our calculated integral elastic and ionization cross sections and the theoretical and experimental data available in the literature, a complete set of integral elastic and inelastic (rotational, vibrational, and electronic excitation, ionization and electron attachment) cross sections, consistent with the reference TCS data, have been derived. This update on the N2O collisional database may help to improve the accuracy of radiation-induced transport models.

Calculations of electron scattering cross sections from tungsten precursors used in FEBID

In this work, the integral elastic, inelastic, ionization, and momentum transfer scattering cross sections of WF6, WCl6, and W(CO)6 molecules are calculated using a quantum mechanical method. These are considered precursors for tungsten deposition using the focused electron beam-induced deposition (FEBID) technique. The spherical complex optical potential (SCOP) formalism is used to figure out the total elastic, inelastic, and momentum transfer cross sections. The complex scattering potential ionization contribution (CSP-ic) method is used to find the ionization cross sections in the inelastic channel. The calculations are performed on a fine grid in the energy range from the ionization potential to 5 keV. We have also reported comparisons of our data with available theoretical and experimental results. All types of scattering cross sections for WCl6 is reported for the first time.

Simulational and theoretical study of electron scattering cross section by Chlormethine-DNA complex

Studying phenomena happening in therapies to conquer cancer has been the aim of extensive research projects in recent years. One of the most practical treatments is utilizing electrons as interacting particles in body tissues. So, studying electron interactions with biological molecules is highly important. Chlormethine as an alkylating agent has always been used since the initial era of cancer chemotherapy. The drug makes interstrand and intrastrand covalent cross-links between two constituents in DNA. In this paper the physical interaction of electrons with Chlormethine drug was reported for the first time. Molecular dynamic (MD) simulations and free energy calculations were carried out to investigate near approach binding of the drug with DNA. Electron scattering cross sections on the system of DNA bases along with Chlormethine as an anticancer drug taken from MD simulations are studied in this paper. Calculations include relativistic Dirac partial-wave which is combined with a local interaction potential. Electron scattering is modelled by the independent atom model (IAM) considering a screening corrected coefficient over an energy range.

Kinetic roles of excited state species in the oxidation of n-pentane/air assisted by nanosecond-pulsed discharge

Despite the significant advancement in plasma assisted combustion recently, many of the underlying plasma/combustion interaction mechanisms remain unknown. Critical data such as cross sections for large hydrocarbons and reaction rate constants involving excited species are still limited. To address these issues, a detailed plasma chemistry mechanism governing the oxidation processes in a n-pentane/air combustion mixture was proposed and studied by including a complete set of e-n-pentane cross section and excited state chemistry of n-pentane. The concentrations of alkane (CH4, C2H6, C3H8), alkene (C2H4, C3H6), methanol, NO2 and NH3 were measured by GC and a small amount of liquid products are qualitatively characterized by GC-MS. The electron-scattering cross sections of n-pentane were obtained by the R-matrix method. The rate constants of excited species of n-pentane which involved the chemical reactions were calculated via Fridman α-model and MMVT method. A linear increase in reactants consumption with increased voltages was observed experimentally, suggesting that n-pentane excitation by plasma was decoupled from the low-temperature chemistry. The kinetic mechanism accurately predicted the generation of alkane and hydrogen and captured the overall trend. However, it underestimated the generation of NH3 and NO2, indicating certain reaction pathways in NH3 and NO2 generation were missed. The results showed that because of the introduction nitrogen in the system, the excited states of the oxidant molecules O(1D), O(1S), N2(B) and N2(C) reacted with n-pentane to form fuel radicals via H-atom abstraction reactions RH + X* → R + XH. The excited species of n-pentane reacted with O, H, OH to form n-pentane radicals via RH* + X → R + XH, accordingly enhancing the chain initial reactions. Importantly, ammonia was produced in a n-pentane/air mixture with plasma assistance through the pathway of N2 → N(2D) → NH → NH2 → NH3. These results highlight strong roles of excited species in a complex n-pentane/air plasma chemistry system.

Numerical investigation of the hybrid pulse–DC plasma assisted ignition and NO[formula omitted] emission of NH[formula omitted]/N[formula omitted]/O[formula omitted] mixture

The ignition delay and NO emission characteristics of the NH3/N2/O2 mixture under the influence of pulse–DC hybrid plasma discharges have been studied. The plasma and combustion chemistry mechanisms for NH3/N2/O2 mixture are reviewed, an improved kinetics mechanism is proposed with a well validated electron scattering cross section data. An improved coupled plasma and combustion chemistry code allowing sensitivity/pathway analysis is developed. The role of key species on the ignition delay time and the effects of low E/N discharge over long periods of time (DC stage) on NOx emission are studied. The results show that, NO emission will be strongly enhanced due to the increased HNO, NH and N density in NH3 containing mixtures in the DC stage, NO density increases with the E/N value in DC stage due to the reduction of NH and NH2 species. The role of O2(a1Δg) in promoting ignition was studied using different rate constant of O2(a1Δg)+NO→O2+NO: O2(a1Δg) mainly reacts with H2 and H to produce radicals such as O, H and OH instead of quenched by NO. The vibrationally excited NH3(v2) molecule plays the dominating role in heat release through V–T relaxation with NH3.

Electron impact scattering and electronic excitation in glycolaldehyde: The first ever detected sugar in space

Detailed theoretical investigations on structural, spectroscopic and electron scattering cross sections of glycolaldehyde, the first ever detected sugar in space are reported in this work. Spectroscopic calculations are performed on the ground and excited states of glycolaldehyde using density functional theory (DFT) and time-dependent density functional theory (TDDFT), respectively. The optimized geometrical parameters and vibrational spectrum are in good agreement with the earlier reported work. Vertical excited state (VES) energies at the TDDFT/B3LYP/aug-cc-PVQZ level of theory along with detailed assignments are reported up to 30 transitions. The TDDFT predicted Rydberg series energies are compared with the Rydberg series of glycolaldehyde converging to its first IP, computed using the standard Rydberg formula and are found to be in good agreement. In the absence of sufficient experimental data on excited states of glycolaldehyde, the theoretical results are validated by comparison of VES calculations performed at the same level of theory with the available experimental data for an analogous molecule viz. acetaldehyde. Triplet excited-state energies for glycolaldehyde are reported here for the first time. Electron impact cross section calculations in the energy range 0.1 to 20 eV are carried out using ab-initio R-matrix method. We have detected one π* shape resonance in all the three models viz. SE, SEP and CC, which may also lead to a possible fragmentation channel wherein a hydrogen atom is removed from the molecule forming a glycolaldehyde dehydrogenated anionic radical (C2H3O2−). The π* shape resonance is correlated with the corresponding molecular orbital electronic structure calculations. Additionally, differential, electronic excitation, ionization and total cross sections are reported here for the first time.

Lepton–Nucleus Interactions within Microscopic Approaches

This review paper emphasizes the significance of microscopic calculations with quantified theoretical error estimates in studying lepton–nucleus interactions and their implications for electron scattering and accelerator neutrino oscillation measurements. We investigate two approaches: Green’s Function Monte Carlo and the extended factorization scheme, utilizing realistic nuclear target spectral functions. In our study, we include relativistic effects in Green’s Function Monte Carlo and validate the inclusive electron scattering cross section on carbon using available data. We compare the flux-folded cross sections for neutrino-carbon scattering with T2K and MINERνA experiments, noting the substantial impact of relativistic effects in reducing the theoretical curve strength when compared to MINERνA data. Additionally, we demonstrate that quantum Monte Carlo-based spectral functions accurately reproduce the quasi-elastic region in electron scattering data and T2K flux-folded cross sections. By comparing results from Green’s Function Monte Carlo and the spectral function approach, which share a similar initial target state description, we quantify errors associated with approximations in the factorization scheme and the relativistic treatment of kinematics in Green’s Function Monte Carlo.

Study of Electron Collisions with Isoprene, 1,2-Butadiene, and Their Isomers.

Isoprene, 1,2-butadiene, and their isomers play an important role in aerosols in the atmosphere, interstellar media, and extraterrestrial life. Since electrons are everywhere, studying how electrons interact with these molecules is an important part of studying such environments. To date, however, little investigation has been conducted in this area. Bearing this in mind, we conducted a thorough investigation to report the various electron scattering cross sections of isoprene, 1,2-butadiene, and their isomers. The methods used for this purpose are reliable within the limits of adopted model potentials. The optical potential method was used to get the total elastic and inelastic cross sections, while the complex scattering potential ionization contribution method was used to get the total ionization cross section from the inelastic contribution. The results from these approximations are pretty close to the results from earlier experiments and theories. Furthermore, most of these isomers are being explored for the first time. Besides, their isomeric effect is also discussed. A correlation between the cross sections of molecules is demonstrated, which can be used to predict cross sections of those molecules where previous data are not available.

Neural network predictions of inclusive electron-nucleus cross sections

We investigate whether a neural network approach can reproduce and predict the electron-nucleus cross sections in the kinematical domain of present and future accelerator-based neutrino oscillation experiments. For this purpose, we consider the large amount of data available to the community via the University of Virginia's Quasielastic Electron Nucleus Scattering Archive and use a residual, fully connected feedforward neural network. We illustrate the training performances of the neural network by comparing its results with experimental data for the electron double-differential cross section on carbon. The agreement between predictions and data is remarkable from quasielastic to deep-inelastic scattering. To test the predicting power of the neural network we consider the numerous kinematical conditions for which experimental cross sections on calcium are available. Furthermore, we show the predictions of the electron-scattering cross sections on oxygen, argon, and titanium: Nuclei of particular interest in the context of present and future accelerator-based neutrino oscillation programs. The agreement between these predictions and the data is comparable to the one of other theoretical models commonly used to calculate electron and neutrino cross sections, such as SuSAv2 and GiBUU. Results obtained with genie, a Monte Carlo event generator, are also discussed for comparison. The good performances obtained with our neural network suggest that neural networks could be exploited for theoretical and experimental investigations of electron- and neutrino-nucleus scattering.

Theoretical process for the investigation of dielectric characteristics of F3NO as an alternative gas for SF6

To examine the possibility of using a gas molecule as an SF6 alternative gas, the insulation properties of the molecule must be estimated. In this work, we present a theoretical approach to calculate geometry parameters, electron scattering cross sections, and transport properties of nitrogen fluoride oxide (F3NO), which we have selected as an alternative to SF6. The molecular minimum structure of F3NO was optimized using the ɷB97X-D functional combined with the aug-cc-pVTZ basis set. Using this initial geometry obtained by the molecular structure calculation, the R-matrix calculation was done to obtain the elastic and momentum transfer cross section. The BE-f method was used for electronic excitation cross section. For the ionization cross section, the binary encounter Bethe method was used. From the calculated cross section data, the electron transport coefficients and reaction coefficients were calculated by solving the two-term approximated Boltzmann equation to investigate the discharge and insulation characteristics.

Methylation and isomerization effects on the elastic electron scattering cross sections by H$$_2$$O$$_2$$ and C$$_2$$H$$_6$$O$$_2$$

Methylation and isomerization effects on the elastic electron scattering cross sections by H$$_2$$O$$_2$$ and C$$_2$$H$$_6$$O$$_2$$

Electron scattering cross sections for the ground and excited states of tin

A comprehensive set of cross sections for electron scattering from the ground and first four excited states of tin has been calculated using the Relativistic Convergent Close-Coupling method. Elastic scattering, momentum transfer, total scattering, and total-inelastic scattering cross sections have been produced for the 5p23P0,1,2, 1D2 and 1S0 states of atomic tin over a projectile energy range of 0.1 eV to 1000 eV. Over the same projectile energy range, state-resolved cross sections for excitations to the 5p2, 5p6s, 5p5d and 5p6p manifolds from the ground and first four excited states of tin are presented. Total single-ionisation cross sections have been calculated which account for the direct ionisation of electrons in the valence 5p and closed 5s shells, as well as indirect contributions from excitation auto-ionisation. These ionisation cross sections are presented for projectile energies up to 1000 eV. Maxwellian rate coefficients have been calculated for all studied transitions over electron temperatures ranging from 0.5 eV to 200 eV and fitted with simple formulas. The fit coefficients are tabulated for use in modelling applications.

Cross Sections for Electron Scattering from Cadmium: Theory and Experiment

Results from the application of optical potential, relativistic optical potential, relativistic convergent close-coupling, and binary encounter Bethe models to electron scattering from gas-phase cadmium are presented. In particular, integral cross sections for elastic scattering, summed discrete electronic-state excitation, and ionization scattering processes are reported over an extended incident electron-energy range. Total cross sections are constructed by taking their sum. Measurements are presented for elastic scattering and for excitation to the 51P1 state. The theoretical and experimental results are compared to previous calculations and measurements. Recommended electron cross-section datasets are constructed over an incident electron energy range of 0.01–10 000 eV.

Electron scattering cross sections from NH3: a comprehensive study based on R-matrix method

In this study, a comprehensive cross-sectional computation on the electron scattering from NH3 was performed using the frame of the R-matrix method. Cross section sets for total elastic, differential, momentum transfer, total ionization, and electronic excitation are presented. The electron-impact dissociation of NH3 to NHH and NH+H2 was considered by summing up the cross sections for the molecular dissociative excitations to the correlated dissociation channels. The reported cross sections for vibrational excitation of NH3 remain controversial and are unable to distinguish the N–H symmetric and asymmetric stretching modes of close frequencies. Here, the excitation cross section for each vibrational mode of NH3 was computed by applying the theoretical approach combining the fixed-nuclei R-matrix method, normal mode approximation and the vibrational frame transformation. The uncertainties of the cross section sets computed in this study were estimated for convenience of use in the plasma modeling.

Combined experimental and theoretical study on the elastic electron scattering cross sections of ethanol

Combined theoretical and experimental studies on the elastic scattering of electrons on ethanol were performed in the energy range of 30–800 eV. The differential elastic electron scattering cross sections (DCS) of ethanol were measured for scattering angles of 30° to 150° using the relative flow technique and nitrogen (N2) as the reference gas. From these experimental DCS, integral elastic and momentum transfer cross sections were estimated. The comparison of the experimental results from the present work to those of other groups showed good agreement within the experimental uncertainty. In addition to the experimental determination, the DCS of ethanol were calculated by applying the independent atomic model with screening-corrected additivity rule and the modified independent atomic model. These theoretical calculations reproduced the experimental data well within the experimental uncertainty, with agreement better at high electron energies as was expected.Graphical abstract

In situ scanning electron microscopy of hydrogen embrittlement by near atmospheric-pressure hydrogen microplasma jet.

Elucidation of microstructures responsible for hydrogen embrittlement is hoped for research and development of high-strength low-alloy steel. For this purpose, a novel in situ scanning electron microscopy method of hydrogen embrittlement was developed by using a near atmospheric-pressure hydrogen microplasma jet excited by pulsed glow discharge. By the developed method, propagations of hydrogen embrittlement cracks in typical martensitic steel, Japanese Industrial Standards SCM435 steel, were successfully observed at frame rates at least up to 10.2Hz with the same image quality as in high vacuum. The hydrogen microplasma jet neither elevated the specimen temperature nor damaged the specimen surface. Strain evolution prior to the crack propagations was also successfully observed in conjunction with the digital image correlation technique. It was found that a small electron scattering cross section of the hydrogen molecule, a large density of hydrogen ions in the near atmospheric-pressure microplasma jet, and stabilization of the glow discharge by the electron beam of the scanning electron microscope play a crucial role in the realization of the in situ observations.