Measurements of vibrationally excited molecules by Raman scattering. II. Surface deactivation of vibrationally excited N2

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Abstract
Wall de-excitation of N2(v=1) was studied on a variety of different solid surfaces. Using 4880 Å laser radiation, we used the intensity of the Q branch of the anti-Stokes Raman scattering at 4382 Å to monitor the N2(v=1) concentration. The vibrationally excited nitrogen was produced by a thermal source and by a microwave discharge. The results were interpreted in terms of the two-dimensional diffusion equation with Poiseuille flow. The two sources of N2(v=1) gave somewhat different values for the wall deactivation coefficient γ. Furthermore, the results with the microwave source depended on the length of exposure of the surface to the afterglow. The observed differences are probably related to the fact that the microwave source also produces atoms and the thermal source does not. The lowest values of γ were recorded for quartz and Pyrex after 24 h of exposure to the afterglow. The results are interpreted in terms of a mechanism of heterogeneous vibrational de-excitation.