Angle-Resolved Electron Scattering from H2O near 0°

An electron beam, characterized by a high-angular discrimination (similar or equal to 0.7 degrees), has been used to measure the total (elastic plus inelastic) cross section of H2O in the energy range 3-100 eV. Broad coincidence is found with recent experiments, including a pronounced shoulder in the 6-12 eV region. However, at energies less than or similar to 6 eV, the present cross sections are similar or equal to 30% higher. Furthermore, forward scattering has been probed in the angular range 0 degrees-3.5 degrees and measures of the average (rotationally and vibrationally summed) differential elastic cross sections for incident energies <= 12 eV are obtained at a scattering angle similar or equal to 1 degrees. The measurements, which provide the first test of theoretical predictions in an angular region experimentally unexplored until now, are found to be within 1 standard deviation of corresponding ab initio R-matrix calculations.