Apparatus for investigating low energy ion-molecule reactors and its application to the reactive scattering of N+ by H2

An apparatus was designed and constructed for measuring the scattering of ions from neutral molecules in a laboratory energy range of 6 to 50 eV. A beam of monoenergetic ions of a specified mass is generated by ionizing the parent neutral in an electron impact source and chen passing the resulting ions through a magnetic momentum analyzer and electrostatic focusing system. The ion beam then passes through a collision cell which contains the neutral target molecules. The scattering ions are detected by a detection system which consists of a crossed electric and magnetic field velocity filter, a quadrupole mass filter and a magnetic electron multiplier. The primary ion source and collision cell are mounted on a rotable cable in a large vacuum chamber and the detection system is mounted on the side of the vacuum chamber. This arrangement allows intensity distributions as a function of angle, mass and velocity to be determined.