Total cross sections for electron scattering by 1-propanol at impact energies in the range 40-500 eV

Abstract

Absolute total cross section (TCS) measurements for electron scattering from 1-propanol molecules are reported for impact energies from 40 to 500 eV. These measurements were obtained using a new apparatus developed at Juiz de Fora Federal University-Brazil, which is based on the measurement of the attenuation of a collimated electron beam through a gas cell containing the molecules to be studied at a given pressure. Besides these experimental measurements, we have also calculated TCS using the Independent-Atom Model with Screening Corrected Additivity Rule and Interference (IAM-SCAR+I) approach with the level of agreement between them being typically found to be very good.

Electron scattering from 1-butanol at intermediate impact energies: Total cross sections

“…19,20 It is well-known [21][22][23] that the valence electronic properties of a molecule, such as its permanent dipole moment (µ) and dipole polarizability (α), affect the scattering dynamics and therefore the scattering cross sections. Here, we are particularly interested in comparing our earlier measured results for methanol, 24 ethanol, 24 and 1-propanol 25 with those we report here for 1-butanol. Each of these species are linear primary alcohols and all have permanent dipole moments in the narrow range µ = 1.55D-1.70 D. 26,27 On the other hand, the dipole polarizabilities for these species are very different, with methanol having α = 3.21 Å 3 , 28 ethanol having α = 4.92 Å 3 , 28 1-propanol having α = 6.67 Å 3 , 28 and 1-butanol having α = 8.57 Å 3 .…”

“…We previously described our experimental apparatus and measurement techniques in some detail 25 so that only a précis of that discussion, in order to make this paper self-contained, needs to be given here. The current apparatus consists of an electron gun, a gas cell, an electron energy analyzer composed of an array of decelerating electrostatic lenses and a cylindrical dispersive 127 ○ analyzer, and a Faraday cup.…”

“…The second, with pumping speed 600 l/s, services the scattering cell and analyzer region. 25 Our apparatus utilizes an in-house designed electron gun and its associated control electronics, which, in principle, covers an energy range from 5 to 500 eV. The performance of this gun was typically very good, providing a suitable focus and collimation into the scattering cell that is necessary for the successful application of the linear transmission technique.…”

“…With these precautions, the variation of ln(It/I 0 ) with P is a straight line whose slope is proportional to the TCS. Similar to our work in 1-proponal, 25 the current measurements were carried out for at least five runs, each run taking at least seven sets of values for P, I 0 , and It. An averaging procedure, with an associated calculation of the standard deviation, was subsequently applied to determine the TCS at a given energy.…”

Recent total cross section measurements in electron scattering from molecules

“…Because alcohols are also used as additions to fuels, their interaction with electrons in scattering processes is important for modeling alcohol combustion through a spark ignition within an engine. Figure 18 shows electron-scattering TCSs for homologous series of linear primary alcohols: methanol, ethanol, 1-propanol, and 1-butanol (C n H 2n+1 OH, n = 1-4), measured recently by Silva et al [118,119] and Gomes et al [120] at intermediate impact energies using the same apparatus; some previous experimental TCS results [121][122][123] are also included for comparison. At energies above 250 eV, TCS measurements of Silva et al for ethanol agree well with respect to the magnitude with earlier data of Sueoka et al [122], being distinctively higher at lower energies.…”