Total cross-section measurements for positrons and electrons colliding with alkane molecules: Normal hexane and cyclohexane

Abstract

Total cross sections (TCSs) for $0.2--1000\phantom{\rule{0.3em}{0ex}}\mathrm{eV}$ positrons and $0.4--1000\phantom{\rule{0.3em}{0ex}}\mathrm{eV}$ electrons colliding with normal hexane and cyclohexane molecules are reported. For positron scattering, low-lying peaks at $0.8\phantom{\rule{0.3em}{0ex}}\mathrm{eV}$ for normal hexane and $1.6\phantom{\rule{0.3em}{0ex}}\mathrm{eV}$ for cyclohexane are observed. For both molecules, positron TCSs are larger than electron TCSs below $2.8\phantom{\rule{0.3em}{0ex}}\mathrm{eV}$; for electron scattering, the main resonance peak in the TCS curve is at $7.5\phantom{\rule{0.3em}{0ex}}\mathrm{eV}$, followed by a shoulder at about $22\phantom{\rule{0.3em}{0ex}}\mathrm{eV}$. TCSs for normal hexane are larger than those for cyclohexane for both positrons and electrons over all the energy range. Striking similarities, more pronounced for electron impact, have been observed between $c$-hexane and benzene TCSs and are attributed to the similarity in molecular structure between these two molecules, whereby each has a hexagonal ring based on the six C atoms.