Rotational Excitation ofH2by Slow Electrons in a Beam Experiment

Rotational excitation and de-excitation $J_f-J_i=\pm 2$, $J_i=0,\cdots ,3\mathrm{}$, of ${\mathrm{H}}_2$ by slow electrons with and without the simultaneous excitation of one vibrational quantum has been measured. The absolute total cross section for pure rotational excitation $J=3\mathrm{}\leftarrow 1$ in the energy range 1-10 eV is presented. The measurements of angular dependences indicate $s$-, $p$-, and $d$-wave scattering.