Tandem mass spectrometers longitudinal

The experiments are best performed using tandem mass spectrometers. One mass spectrometer is used to mass-select the incident ion X+, which is subsequently retarded to the required velocity before collision with the gaseous neutral M. The ions M+ and its ionic fragmentation products are extracted from the collision chamber, either perpendicularly or in-line (longitudinally) with the incident beam and mass-analysed with the second mass spectrometer. The incident ion, X+, energies may be as low as 0.1 eV, which loosely corresponds to a translational temperature of something like 800 K. 

Maier [170] and Lindemann et al. [171] have carried out cross-section measurements of reaction (107) as a function of ion kinetic energy. Maier used a longitudinal tandem mass spectrometer and Lindemann et al. a perpendicular tandem mass spectrometer. Thus the ion kinetic energies were rather well defined in both of the studies. C ions were produced by electron bombardment of CO under such conditions that all projectiles were in the ground state. Their results are summarized in Fig. 19 in which cross-sections are plotted versus barycentric energy. 

Fig. 3. The pulsed ejection of product ions from the collision chamber using a pulsed, longitudinal tandem mass spectrometer. The positive ejection pulse is applied to the entrance slit of the collision chamber immediately after the primary ions have left the collision chamber. The figure shows the energy analysis of the product ions (by retarding potential analysis) observed under two conditions ...

Maier (longitudinal tandem mass spectrometer) and Teloy and Gerlich (guided-ion-beam technique). (The former data were taken from their published paper and may be inaccurate, since the figure therein was small and the data were plotted on a logarithmic scale.) Note that in neither case has correction been made for target motion. Ep is the laboratory energy of the neon ion. 

I.Szabo, Theoretical analysis of consecutive ion-molecule reactions. I. The mechanisms in a tandem mass spectrometer of perpendicular type. II. The mechanisms in a tandem mass spectrometer of longitudinal type, Int. J. Mass Spectrom. Ion Phys. 3, 103-129, 169-188(1969). 

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