Low-energy electron scattering from the water molecule: Angular distributions and rotational excitation

Abstract

The scattering of electrons from the H2O molecule in its ground electronic state is analyzed by carrying out quantum calculations of the coupled equations in the body-fixed (BF) frame and using exact static-exchange interaction forces (ESE) within a single-center expansion (SCE) formulation. The effect of correlation-polarization forces is included via a density functional approach and the necessary corrections to the nonconvergent behavior of the angular distributions from fixed nuclei calculations involving polar molecules are carried out. Elastic and rotationally inelastic differential and momentum transfer cross sections are compared with experiments and the effects on the inelastic processes of the long-range dipolar potential are examined in some detail. The electron efficiency in exciting molecular rotations over a broad range of energies is also obtained and discussed.

Low-energy electron collisions with water: elastic and rotationally inelastic scattering

“…The expected dominant contribution of the dipolar (0→1) rotational transition at forward angles is clearly shown. However, in contrast to the higher energy calculations by Gianturco et al (1998), the pure elastic (0→0) transition becomes dominant at backward angles. This result indicates the crucial role of the shortrange interactions, as described by the low-partial waves, in the backward scattering region.…”

“…Hence, above 7 eV, electronic excitation and geometry effects will start to have some effect. For this reason, we made no attempt to investigate the other energies (15, 40 and 50 eV) reported by Cho et al (2003 Johnstone and Newell (1991) and the theoretical results of Gianturco et al (1998) give good agreement (Faure et al 2003).…”

Transport coefficients and cross sections for electrons in water vapour: Comparison of cross section sets using an improved Boltzmann equation solution

“…Furthermore, since there are insufficient rotational cross sections in the proposed set of Itikawa and Mason, 11 they cannot be comprehensively tested for accuracy against the transport coefficient measurements as they are incomplete. Note that rotational cross sections calculated by the methods of Faure et al 44 and Gianturco et al 45 are more accurate than those from Itikawa. 32 However, once again, their results 44,45 are not available over the entire energy range we require or for the number of channels we need.…”

“…Note that rotational cross sections calculated by the methods of Faure et al 44 and Gianturco et al 45 are more accurate than those from Itikawa. 32 However, once again, their results 44,45 are not available over the entire energy range we require or for the number of channels we need. Therefore, at this time, we have not been able to test them with our approach.In view of this dilemma, we have chosen for the moment to abide by the rotational cross sections used by Ness and Robson, 1 which after all reproduce the measured transport data.…”

Radiation damage to DNA: Electron scattering from the backbone subunits

“…This divergence can be readily eliminated by considering rotations of the molecule, as a Born closure expansion. 31 We have not implemented this here, as in our previous work on the DNA bases, because this level of detail is not our present interest. Moreover, the dipole moments here are also less than half what they were for the DNA and RNA bases, so the correction will be even less important here.…”