Bare-carbon-ion-impact electron emission from adenine molecules: Differential and total cross-section measurements

Abstract

Double-differential ionization cross sections (DDCS) for bare-carbon-ion-induced ionization of vapor-phase adenine molecules (${\text{C}}_{5}{\text{H}}_{5}{\text{N}}_{5}$) have been measured. The experiment has been performed using an electron spectroscopy technique. Electrons ejected from adenine were analyzed by a hemispherical electrostatic deflection analyzer over an energy range of $1\text{--}450\phantom{\rule{0.28em}{0ex}}\mathrm{eV}$ for emission angles from ${20}^{\ensuremath{\circ}}$ to ${160}^{\ensuremath{\circ}}$. The single-differential cross section (SDCS) and total ionization cross section were also deduced. The experimental results have been compared with the continuum distorted wave-eikonal initial-state model calculation. We have observed a very good agreement between the theory and experiment. The angular distribution of the DDCS, SDCS and the asymmetry parameter for low-energy (${E}_{e}\ensuremath{\le}0.5$ a.u.) electron display an oscillatory behavior which is in contrast to that observed in ion-atom collisions. A comparison is also made with available experimental cross-section results for uracil target colliding with the same velocity bare carbon ions and the scalability of ionization cross sections among these molecules is discussed.