Angle-Dependence of Ion Kinetic Energy Spectra Obtained by Using Mass Spectrometers. II. Experimental Considerations and Preliminary Results on Non-Fragmenting Systems

Experimental problems associated with studies of the scattering of kilovolt projectile ions in mass spectrometers designed primarily for chemical analysis are discussed. The parameters that are important in satisfactorily controlling and defining the actual scattering angle in relation to the observation angle are considered in detail. Two different experimental configurations are considered; angular selection before, or after kinetic energy analysis of the collision products. A modification to a VG ZAB-2F double-focusing mass spectrometer, in order to observe angle-resolved ion kinetic energy spectra of collisionally scattered ion beams, is described. Initial angle-resolved experiments on systems that do not involve fragmentation, have been performed. The results are presented for the angle-resolved energy loss spectra of Ar^+ and N^+_2 and the angle-resolved charge-stripping of Ar^+. A feature of the apparatus described is the small uncertainty in the angular selection of the analysing angle-resolved slit.