Electron-Impact Vibrational Excitation of H₂O

Cross sections for excitations of the three fundamental vibrational modes of H 2 O by electron collisions are calculated with the use of the Born theory for the collision energies from the threshold to 100 eV. Electron-molecular multipole (dipole and quadrupole) interactions, as well as polarization force, are taken into account. The dominance of the quadrupole interaction relative to the dipole one prevents the cross section from falling rapidly as the energy increases, resulting in a fairly large cross section even in the high energy range (\({}10\) eV). Differential cross sections are also calculated at 1, 15, and 53 eV. For the latter two incident energies, a comparison is made with the relative differential cross section measured by Trajmar et al.