Absolute measurements of elastic scattering and vibrational excitation of the NO molecule by low energy electron impact (0.4–2.5 eV) are presented. They show that previous estimates of these cross sections may be in error by as much as a factor of 3 and provide compelling evidence for a reassessment of the balance between elastic scattering and vibrational excitation at incident energies below 2 eV. They also confirm the critical contribution that intermediate negative ion resonances ($\mathrm{N}{\mathrm{O}}^{\mathrm{-}}$) make to the various scattering processes for this molecule at low incident energies.

• Received 17 February 2003

DOI:https://doi.org/10.1103/PhysRevLett.90.203201