Anisotropic fragmentation in low-energy dissociative recombination

On a dense energy grid reaching up to 75 meV electron collision energy the fragmentation angle and the kinetic energy release of neutral dissociative recombination fragments have been studied in a twin merged beam experiment. The anisotropy and the extracted rotational state contributions were found to sensitively depend on energy. Both show pronounced variations on a likewise narrow energy scale as the rotationally averaged rate coefficient. For the first time angular dependences described by Legendre polynomials higher than 2nd order could be deduced. Moreover, a slight anisotropy at zero collision energy was observed which is caused by the flattened velocity distribution of the electron beam.