Collisional alignment

Two recent papers [1,2] provide updated views of advances in the production of intense and continuous beams of aligned molecules. In [1], it was demonstrated that in the prototypical case of a seeded supersonic expansion of a molecular beam of benzene, besides acceleration and cooling, orientation of the molecular plane also occurs because of the anisotropy of the intermolecular forces which govern collisions. This work is reviewed in Sec.2.1. Previous studies on the collisional alignment of the rotational... 

Though at high E/N the ion transport depends in a complex way on collision integrals of various orders (2.2.1), all those quantities in classic transport theory are orientationally averaged. This implies free rotation of ions regardless of E, which is true only for atomic ions or at sufficiently low E. Polyatomic ions in gas can be oriented with respect to E by two unrelated mechanisms—collisional alignment considered here and dipole alignment (2.7). 

Collisional alignment was thus far studied only for small species (diatomic and triatomic). The work following pioneering experiments of Richard N. Zare at Stanford has used the velocity slip in molecular beams (e.g., He, Ne, Ar, or H2) seeded by heavier neutrals (e.g., alkali dimers, I2, CO, or Supersonic... 

Unlike collisional alignment (2.5) that requires gas by definition, the dipole alignment may occur in its absence. Efforts to align polar molecules in crossed-beam... 

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