  The ability of gas-surface dynamics studies to resolve the velocity
distribution of the scattered species in the 2D sacattering plane has been
limited by technical capabilities and only a few different approaches have been
explored in recent years. In comparison, gas-phase scattering studies have been
transformed by the near ubiquitous use of velocity map imaging. We describe an
innovative means of introducing a surface within the electric field of a
typical velocity map imaging experiment. The retention of optimum velocity
mapping conditions was demonstrated by measurements of iodomethane-d3
photodissociation and SIMION calculations. To demonstrate the systems
capabilities the velocity distributions of ammonia molecules scattered from a
PTFE surface have been measured for multiple product rotational states.
