Vibrational excitation of symmetric and bending modes of H2O by slow electron impact

Electron impact vibrational excitation cross sections (differential, integral and momentum transfer) for the symmetric (100) and the bending (010) modes of the H 2 O molecule are calculated in the fixed-nuclei and the impulse approximations from threshold to 10 eV. The normal coordinate dependent K-matrix elements are augmented with the laboratory frame first Born matrix elements for higher angular momenta in order to obtain converged cross sections via a closure formula. A sharp threshold peak and a broad resonance structure is seen around 6-8 eV in the integral cross section in agreement with the recent observations: while the A 1 scattering state plays a not unimportant role, the major contribution to this broad feature is due to the B 2 state. All results compare well with the crossed-beam experimental results of Seng and Linder (1974).