Beam orientation and velocity selection

At beam velocities greater than thermal, velocity selection is not normally used (except for sputter-ion sources) since the methods of supersonic beams, seeded supersonic beams and charge-exchange tend to produce very narrow velocity distributions (see Section 3.2.2). 

Velocity and angular analysis of the product CsCl from Cs + CCI4 was obtained by Wilson [142] and Herschbach [8]. This system is intermediate in mechanism between the stripping and rebound mechanisms (see Section 3.3.1), and it was confirmed, as had often been inferred from kinematic arguments, that most of the heat of reaction is liberated as internal excitation, rather than as kinetic energy, of the products. 

Velocity selected beams have been used to determine the threshold translational energies and the variation of the reaction cross-section with relative kinetic energy, e.g. K + CH3I [217] and K + HBr [132, 218]. The 

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