Magnetically confined electron beam system for high resolution electron transmission-beam experiments

Lozano, A.; Oller, J.C.; Krupa, K.; Silva, F. Ferreira da; Limão‐Vieira, P.; Blanco, F.; Muñoz, Antonio; Colmenares, Rafael; García, Gustavo

doi:10.1063/1.5030068

Cited by 23 publications

(89 citation statements)

References 20 publications

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“…1 are the TCS results from the previous measurements of Wan et al 14 and Karwasz et al, 15 along with theoretical IAM-SCAR+I and IAM-SCAR+I+rotations total cross sections of Krupa et al 12 and an SCOP result of 15 (green crosses) and theoretical IAM-SCAR+I (blue solid curve) 12 and IAM-SCAR+I+rotations (blue short dashed curve) 12 and SCOP (brown dotted curve) 16 results. The IAM-SCAR+I+rotations result when corrected for the "missing angle" effect (black dotted-dashed curve) 19 and the measured elastic ICSs of Hlousek et al 13 (red open circles) are also shown. Note that the uncertainties on the present data are statistical only.…”

Section: Resultsmentioning

confidence: 99%

“…Other random uncertainties are related to the temperature measurement (∼1% according to the manufacturer's data) and the numerical fitting procedure (∼1%) associated with the analysis of the RPA cut-off curves. 19 By combining these uncertainties, a total error limit of ±6% has been determined for the present TCSs. Systematic errors linked to the experimental configuration are those connected to the so-called "missing angles."…”

Section: Methodsmentioning

confidence: 98%

“…The present apparatus and our measurement techniques have been explained in detail previously, [17][18][19] but nonetheless, to ensure this paper is largely self-contained, some of their more important facets are summarised here again. Our transmission-beam attenuation spectrometer consists of a linear electron beam that is confined by an intense (∼0.1 T) axial magnetic field, which converts any scattering event into a kinetic energy loss in the forward direction (i.e., parallel to the applied magnetic field 19 ). The primary electron beam, generated through thermionic emission from a tungsten filament, is cooled and confined in a magnetic molecular nitrogen (N 2 ) gas trap (GT), which reduces the initial energy spread (∆E) of 500 meV down to about 200 meV (see Table I).…”

Section: Methodsmentioning

confidence: 99%

“…The primary electron beam, generated through thermionic emission from a tungsten filament, is cooled and confined in a magnetic molecular nitrogen (N 2 ) gas trap (GT), which reduces the initial energy spread (∆E) of 500 meV down to about 200 meV (see Table I). Pulsed voltages, applied to the trap electrodes, 19 produce a pulsed electron beam with a well-defined energy (and relatively narrow ∆E) to enter into the scattering cell. The scattering chamber (SC) is a 40 mm long gas cell, defined by two 1.5 mm diameter entrance and exit apertures, through which the pulsed electron beam passes when the CH 2 Cl 2 pressure inside the chamber is varied from 0 to 2.5 mTorr (as measured by a MKS-Baratron 627B absolute capacitance manometer), with the upper limit being chosen to ensure multiple scattering effects are avoided.…”

Section: Methodsmentioning

confidence: 99%

“…As detailed in Ref. 19, and also in the studies of Fuss et al 17 and Sanz et al, 18 the magnitude of this systematic error (σ(∆θ)) can be evaluated from the available theoretical data (in this case, the IAM-SCAR+I+ rotations results of Krupa et al 12…”

Section: Methodsmentioning

confidence: 99%

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Total cross section measurements for electron scattering from dichloromethane

Lozano

Álvarez

Blanco

et al. 2018

The Journal of Chemical Physics

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Using our magnetically confined electron transmission apparatus, we report the results of total cross sections (TCSs) for electron scattering from dichloromethane (CH 2 Cl 2). The energy range of this study is 1-300 eV. Wherever possible, the present data are compared to earlier measured TCSs of Wan et al. [J. Chem. Phys. 94, 1865 (1991)] and Karwasz et al. [Phys. Rev. A 59, 1341 (1999)] and to the corresponding theoretical independent atom model with screening corrected additivity rule and interference term (IAM-SCAR+I) results of Krupa et al. [Phys. Rev. A 97, 042702 (2018)] and a spherical complex optical potential formulation calculation of Naghma et al. [J. Electron Spectrosc. Relat. Phenom. 193, 48 (2014)]. Within their respective uncertainties, the present TCS and those of Karwasz et al. are found to be in very good agreement over their common energy range. However, agreement with the results of Wan et al. is quite poor. The importance of the experimentally inherent 'missing angle' effect (see later) on the measured TCS is investigated and found to be significant at the lower energies studied. Indeed, when this effect is accounted for, agreement between our measured TCSs and the corrected IAM-SCAR+I+rotations calculation results are, for energies above about 3 eV, in good accord (to better than 8%). Finally, we observe two σ * shape resonances, consistent with the earlier electron transmission spectroscopy results of Burrow et al. [J. Chem. Phys. 77, 2699 (1982)], at about 2.8 eV and 4.4 eV incident electron energy, in our measured TCS.

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 98%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Total cross section measurements for electron scattering from dichloromethane

Lozano

Álvarez

Blanco

et al. 2018

The Journal of Chemical Physics

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Total electron scattering cross section from sevoflurane by 1–300 eV energy electron impact

Lozano

Silva

Blanco

et al. 2018

Chemical Physics Letters

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We report on novel total electron scattering cross section (TCS) measurements for electrons scattering from sevoflurane, at incident electron impact energies in the range 1-300 eV. The experimental results, obtained from a newly implemented magnetic beam apparatus based in Madrid, are compared with theoretical results from the independent atom model with screening corrected additivity rule including interference effects and rotational excitation (IAM-SCAR+I+R). A very good level of agreement has been found between the present experimental and theoretical data at above about 20 eV electron impact and to within the experimental uncertainties.

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Electron and Positron Scattering Cross Sections from CO₂: A Comparative Study over a Broad Energy Range (0.1–5000 eV)

et al. 2022

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In this Review, we present a comparative study between electron and positron scattering cross sections from CO 2 molecules over a broad impact energy range (0.1–5000 eV). For electron scattering, new total electron scattering cross sections (e-TCS) have been measured with a high resolution magnetically confined electron beam transmission system from 1 to 200 eV. Dissociative electron attachment processes for electron energies from 3 to 52 eV have been analyzed by measuring the relative O – anion production yield. In addition, elastic, inelastic, and total scattering cross section calculations have been carried out in the framework of the Independent Atom Model by using the Screening Corrected Additive Rule, including interference effects (IAM-SCARI). Based on the previous cross section compilation from Itikawa ( J. Phys. Chem. Ref. Data 2002 31 749 767 ) and the present measurements and calculations, an updated recommended e-TCS data set has been used as reference values to obtain a self-consistent integral cross section data set for the elastic and inelastic (vibrational excitation, electronic excitation, and ionization) scattering channels. A similar calculation has been carried out for positrons, which shows important differences between the electron scattering behavior: e.g., more relevance of the target polarization at the lower energies, more efficient excitation of the target at intermediate energies, but a lower total scattering cross section for increasing energies, even at 5000 eV. This result does not agree with the charge independence of the scattering cross section predicted by the first Born approximation (FBA). However, we have shown that the inelastic channels follow the FBA’s predictions for energies above 500 eV while the elastic part, due to the different signs of the scattering potential constituent terms, remains lower for positrons even at the maximum impact energy considered here (5000 eV). As in the case of electrons, a self-consistent set of integral positron scattering cross sections, including elastic and inelastic (vibrational excitation, electronic excitation, positronium formation, and ionization) channels is provided. Again, to derive these data, positron scattering total cross sections based on a previous compilation from Brunger et al. ( J. Phys. Chem. Ref. Data 2017 46 023102 ) and the present calculation have been used as reference values. Data for the main inelastic channels, i.e. direct ionization and positronium formation, derived with this procedure, show excellent agreement with the experimental results available in the literature. Inconsistencies found between different model potential calculations, both for the elastic and inelastic collision processes, suggest that new calculations using more sophisticated methods are required.

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Magnetically confined electron beam system for high resolution electron transmission-beam experiments

Cited by 23 publications

References 20 publications

Total cross section measurements for electron scattering from dichloromethane

Total cross section measurements for electron scattering from dichloromethane

Total electron scattering cross section from sevoflurane by 1–300 eV energy electron impact

Electron and Positron Scattering Cross Sections from CO₂: A Comparative Study over a Broad Energy Range (0.1–5000 eV)

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Magnetically confined electron beam system for high resolution electron transmission-beam experiments

Cited by 23 publications

References 20 publications

Total cross section measurements for electron scattering from dichloromethane

Total cross section measurements for electron scattering from dichloromethane

Total electron scattering cross section from sevoflurane by 1–300 eV energy electron impact

Electron and Positron Scattering Cross Sections from CO2: A Comparative Study over a Broad Energy Range (0.1–5000 eV)

Contact Info

Product

Resources

About

Total electron scattering cross section from sevoflurane by 1–300 eV energy electron impact

Electron and Positron Scattering Cross Sections from CO₂: A Comparative Study over a Broad Energy Range (0.1–5000 eV)