Electron-impact vibrational excitation of water molecules

Cross sections (differential and integral) for the electron-impact vibrational excitation of H 2 O are calculated at the collision energies 6-50 eV. Excitation of the three fundamental modes of vibration, (100), (010) and (001), is considered separately. The calculation is based on the rotationally sudden and a vibrationally close-coupling method taking an ab initio electrostatic potential. The effects of electron exchange and target polarization are taken into account approximately. The resulting cross sections are compared with the experimental data available. A comparison is also made with the Born cross section, which is often cited in experimental papers. Qualitatively, the present differential cross sections well reproduce the experimental data, particularly the angular dependence of the cross section. Quantitatively, on the other hand, there are some disagreements between the present calculation and the experimental data.