Excitation of the Q1 1Σg+ doubly excited state of H2 by electron impact

400 eV electrons were used to excite the autoionizing state Q(1)(1)Sigma (+)(g) of H(2). The relative cross section was measured as a function of: (1) the angle between the internuclear axis and the momentum transfer vector of the collision; and (2) energy loss for a fixed orientation of the molecular axis in the laboratory frame. In the first set of measurements electrons scattered at 18 degrees with an energy loss of 29 eV were detected in coincidence with a 2 eV H(+) ion resulting from dissociation following autoionization. The angular distribution of the 2 eV ions was recorded and fitted to calculated values. A maximum was found when the internuclear axis was aligned with the momentum transfer vector. Secondly, the relative yield of 2 eV H(+) ions was measured as a function of energy loss in the electron-H(2) collisions. Energy loss ranged from 23 to 35 eV. The lowest lying Q(1)(1)Sigma (+)(g), (1)Sigma (+)(u) and (1)Pi (g) were included in the calculated fit to the data.