Simultaneous measurements of angular and velocity distributions

A pioneering work on the simultaneous measurement of the angular and velocity distributions was carried out by Champion et al. [98—101] following the velocity work of Vance and Bailey [94] described above. Their apparatus, a tandem mass spectrometer system, consists essentially of three sections a primary ion gun, a collision chamber, and a product-ion analyser and detector. A mass-analysed, velocity-selected ion beam is directed into the collision chamber containing target gas at low pressure. The product ions are velocity-analysed with a 127° electrostatic velocity selector and mass-analysed in a quadrupole mass filter. The angular distributions of the product ions are obtained by rotating the analyser-detector system about the centre of the collision chamber. 

the Ms and Fa are the masses and the energy of the particle indicated by the subscripts, and E and Q are the centre-of-mass energy and the energy transformed from internal to translational motions, respectively. The positive and negative signs in eqn. (75) refer to x = 0° and 180°, respectively. Thus it follows that if product ions are observed at 0 = 0° with energies less than 

Doverspike et al. [99] explained the back-scattering as partly due to head-on collisions and partly to complex formation. The complex forma- 

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