Electron collisions with small esters: A joint experimental-theoretical investigation

Abstract

A theoretical and experimental investigation on elastic electron scattering by two small esters, namely, methyl formate and ethyl acetate, is reported. Experimental differential, integral, and momentum-transfer cross sections are given in the 30--1000 eV and ${10}^{\ensuremath{\circ}}--{120}^{\ensuremath{\circ}}$ ranges. The relative-flow technique was used to determine such quantities. Particularly for methyl formate, a theoretical study was also carried out in the 1--500 eV range. A complex optical potential derived from a Hartree-Fock molecular wave function was used to represent the collision dynamics, whereas the Pad\'e approximation was used to solve the scattering equations. In addition, calculations based on the framework of the independent-atom model (IAM) were also performed for both targets. In general, there is good agreement between our experimental data and the present theoretical results calculated using the Pad\'e approximation. The theoretical results using the IAM also agree well with the experimental data at 200 eV and above. Moreover, for methyl formate, our calculations reveal a ${}^{2}{A}^{\ensuremath{'}\ensuremath{'}}$ $({\ensuremath{\pi}}^{*})$ resonance at about 3.0 eV and a ${\ensuremath{\sigma}}^{*}$-type resonance centered at about 8.0 eV in the ${}^{2}{A}^{\ensuremath{'}}$ scattering channel. The ${\ensuremath{\pi}}^{*}$ resonance is also seen in other targets containing a carbonyl group.