Product Rotational Polarization in the Li+HF ( v=0, j=0) Reaction and Its Isotopic Variants

Product rotational polarization in the title reactions is investigated by employing the quasi-classical trajectory method. An accurate ground 1²A' potential energy surface J. Chem. Phys. 107 (1997) 10085 and a collision energy of 110 meV are adopted in these calculations. The commonly used rotational alignment parameter A₀⁽²⁾ and the three angular distributions P(θ_r), P(φ_r), and P(θ_r ,φ_r) (θ_r and φ_r being the polar angles of the product angular momentum) are computed in the c.m. frame to gain insight into the product rotational alignment and orientation. It is found that the product rotational angular momentum prefers not only to align perpendicular to the reagent relative velocity vector k but also orientate along the negative y axis, which is successfully interpreted by an impulsive mode. The isotope mass effect on the product rotational polarization is also revealed and discussed.