Methylation and isomerization effects on the elastic electron scattering cross sections by H$_2$O$_2$ and C$_2$H$_6$O$_2$

Abstract

Integral, differential and momentum-transfer elastic cross sections for the scattering of low-energy electrons by hydrogen peroxide (HP), dimethyl peroxide (DMP) and ethylene glycol (ETG) are reported. These cross sections were calculated in the static-exchange and static-exchange plus polarization approximations for energies up to 30 eV by using the Schwinger multichannel method implemented with norm-conserving pseudopotentials. Through the symmetry decomposition of the integral cross section according to the C$_{2h}$ point group and the diagonalization of the scattering Hamiltonian, shape resonances were assigned to all three molecules. One shape resonance, namely $\sigma _\mathrm{{OO}}^{*}$ of $B_u$ symmetry, was observed for HP around 2.5 eV. Due to the elongation of the O–O bond, when methyl groups are added to HP to form DMP, this resonance is shifted toward 2.1 eV in the DMP integral cross section. For DMP and ETG, a second peak, a broad structure that originates from the superposition of shape resonances of $A_g$, $A_u$ and $B_u$ symmetries, was observed for higher impact energies. By comparing the cross sections of DMP and ETG, we found that the most striking differences appear in the low-energy regime, while for higher impact energies the cross sections are very similar, as expected for isomers.

Graphical abstract