Positron and electron collisions with nitrous oxide: Measured and calculated cross sections

Abstract

. Positron and electron collisions with nitrous oxide: measured and calculated cross sections. Physical Review A: Atomic, Molecular and Optical Physics, 88 (2), 022708-1-022708-10. Positron and electron collisions with nitrous oxide: measured and calculated cross sections AbstractWe present cross-section results from an experimental and theoretical study on positron scattering from nitrous oxide. Total cross sections (TCSs) have been measured at incident energies between 0.1 and 70 eV with a linear-transmission-based positron spectrometer. Elastic differential and integral cross sections, as well as inelastic integral cross sections and TCSs, have been computed with two different theoretical approaches: the independent atom model with screening-corrected additivity rule (IAM-SCAR), at energies in the 1-to 1000-eV range, and the Schwinger multichannel method at energies between 0.1 and 10 eV. Note that the latter method specifically reports cross sections for the elastic channel. We find good qualitative agreement between the theories and the TCS experiment at all common energies. That level of accord is found to also become quantitative above the ionization energy of nitrous oxide. Electron-impact TCSs calculated with the IAM-SCAR approach are also presented and compared to the existing results in order to uncover any similarities or differences in the scattering processes between these two leptons and nitrous oxide. We present cross-section results from an experimental and theoretical study on positron scattering from nitrous oxide. Total cross sections (TCSs) have been measured at incident energies between 0.1 and 70 eV with a linear-transmission-based positron spectrometer. Elastic differential and integral cross sections, as well as inelastic integral cross sections and TCSs, have been computed with two different theoretical approaches: the independent atom model with screening-corrected additivity rule (IAM-SCAR), at energies in the 1-to 1000-eV range, and the Schwinger multichannel method at energies between 0.1 and 10 eV. Note that the latter method specifically reports cross sections for the elastic channel. We find good qualitative agreement between the theories and the TCS experiment at all common energies. That level of accord is found to also become quantitative above the ionization energy of nitrous oxide. Electron-impact TCSs calculated with the IAM-SCAR approach are also presented and compared to the existing results in order to uncover any similarities or differences in the scattering processes between these two leptons and nitrous oxide.

Cross Sections for Positron Impact with 2,2,4-Trimethylpentane

“…First, the geometrical length of the interaction region (L = 22.1 ± 0.1 mm) was corrected for the gyration of the positrons in the magnetic field. 24 That correction increased L by 5.5% (with B ≈ 11 G) at all incident energies, except at E ≥ 37.5 eV when the magnetic field was reduced to B ≈ 4 G, and hence, the correction was just 2%. Moreover, as an MKS 627B capacitance manometer operating at 45 °C was used to measure the pressure in the scattering chamber, whereas the temperature of the vacuum chamber was ∼64 ± 2 °C, a thermal transpiration correction was applied to the pressure readings.…”

“…The measured data were corrected for some inevitable instrumental effects before being used to determine the TCSs. First, the geometrical length of the interaction region ( L = 22.1 ± 0.1 mm) was corrected for the gyration of the positrons in the magnetic field . That correction increased L by 5.5% (with B ≈ 11 G) at all incident energies, except at E ≥ 37.5 eV when the magnetic field was reduced to B ≈ 4 G, and hence, the correction was just 2%.…”

“…The IAM-SCAR method has been widely employed to compute both electron ,− and positron ,,− scattering cross sections for a large variety of molecular targets and over an extensive energy range, typically from 1 to 5000 eV. Therefore, we only briefly summarize the main features of that formalism here.…”

Cross sections for positron and electron collisions with an analog of the purine nucleobases: Indole

“…Given the largely polar nature of indole, which has both a very large permanent dipole moment and static dipole polarizability (Table I), the observed TCS behavior is likely to be related to those important intrinsic physicochemical properties of the target. In fact, we have seen in our earlier studies on polar polyatomic species (see, e.g., [58,[68][69][70]) that those properties can play an important role in the low-energy scattering dynamics. This point was also examined in depth by Brunger and Zecca [71].…”

Low energy positron interactions with uracil—Total scattering, positronium formation, and differential elastic scattering cross sections

“…Representing the Ps formation channel is a challenging task and we have adopted a phenomenological approach, as discussed in Ref. 25.…”