Angular momentum polarization in molecular beams of I 2 and Na 2

Abstract

The degree of molecular alignment, due to nozzle expansion, has been determined in supersonic beams of I 2 and Na 2, using the technique of laser-induced fluorescence. It is found that the anisotropic distribution of angular momenta is of the form 1 + α 2 P 2(cos ϑ). The alignment appears to be small for I 2 while for Na 2 a considerably larger effect is measured. Two internal states are studied, v = 0, J = 28 and v = 3, J = 43; both under various source conditions. It is found that the alignment depends on the internal state of the molecule and for each state can be described as a unique function of pd, the product of source pressure and nozzle diameter. The results are explained using a moel based on scattering between atoms and dimers with different velocity distributions. It is suggested that alignment may be a general feature in seeded molecular beams containing nonspherical components.