Detection of vibrationally excited nitrogen by trapped electron and electron transmission methods

摘要

Two techniques for detection of vibrationally excited nitrogen using low-energy electron scattering are described. The first technique uses the trapped electron method to observe excitation from N2ν into the B3Пg state near threshold. From the known Franck-Condon factors, the contribution from excited vibrational levels may be unfolded. The second technique employs the electron transmission method to detect sharp structure in the total scattering cross section resulting from the formation of temporary negative ions. Because of uncertainties in the total scattering cross sections from each of the vibrational levels, the transmission method is less accurate than the trapped electron technique. As a consistency check, the vibrational temperature of N2 downstream from a microwave discharge is determined as a function of the discharge power. Within their respective error limits, the two methods are in good agreement.