A molecular beam study of electronic to electronic, vibrational, and rotational energy transfer in the collision of two step laser excited sodium with N2

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Abstract
The quenching of excited Na* (4d,5s,4p,4s) by N2 has been studied in a crossed atomic and molecular beam apparatus at thermal collision energies. The sodium atoms are excited by two laser beams of different wavelengths to either the 42D5/2 or 52S1/2 state, via the intermediate 32P3/2 state. For both excitation schemes optical relaxation processes lead to a population in the 42P3/2 and 42S1/2 states of several percent. The relative densities of the excited states have been calculated from rate equations using stationary conditions. The measured energy transfer spectra show high scattering intensities at low kinetic energies together with some structure at medium energies. This structure can be partially disentangled using the results of the previously studied Na*(32P3/2)+N2 quenching process. The main conclusion is that collisional deexcitation to the Na(3s) ground state is negligible, whereas among the higher levels the collisional energy transfer cross sections are between 0.5 and 7.5 times the magnitude of the 3p–3s quenching cross section and they are strongly forward peaked in the same way. Relative values for the differential quenching cross sections are reported.