Path integral approximation of state- and angle-resolved inelastic scattering

'We construct a path integral based approximation to rotationally inelastic collisions from which differential scattering cross sections are obtained for a number of atom-diatom systems. These are found to be in good agreemen t with IOS calculations on the same systems. In this approximation, the cla ssical and near-classical paths that control scattering from a quantized sy stem are deduced and this process reveals the origins of interference effec ts seen in theoretical calculations and some experimental measurements of a ngular distributions. This formulation provides physical insight into the i mportant trajectories in systems where one or more degrees of freedom are q uantized and could be regarded as an extension of classical S matrix theory , which for simple systems do not require root finding methods. (C) 1999 Am erican Institute of Physics. [S0021-9606(99)01612-8].