MOLECULAR-BEAM SCATTERING OF NITROGEN MOLECULES IN SUPERSONIC SEEDED BEAMS - A PROBE OF ROTATIONAL ALIGNMENT

Measurements of total integral cross sections for scattering of nitrog en molecules by Xe atoms in the glory collision energy range (40-600 m eV) are reported under two different experimental conditions, using ei ther a rotationally ''hot'' (most probable levels J = 8, 9) effusive b eam of nitrogen (obtaining information on the isotropic component of t he interaction potential) or rotationally ''cold'' N-2 Seeded beams em erging from supersonic expansions (obtaining quantitative information on rotational alignment of molecular nitrogen). The scattering results presented in this paper allow us to establish that the recently repor ted phenomenon of the strong correlation between the degree of collisi on-induced alignment and the speed of the molecules within a supersoni c seeded velocity distribution, as previously observed for the first t ime in molecular oxygen, also occurs for the case of nitrogen molecule s. Alignment parameters are reported for both the ortho and para forms of nitrogen, which are cooled down in the seeded supersonic expansion process to their lowest rotational levels J = 0, 1, 2.