A compact electrostatic lens for velocity map imaging experiments

The traditional three-electrode Velocity Map Imaging (VMI) electrostatic lens developed by Eppink and Parker has proven to be a useful tool in a wide range of applications in molecular dynamics, including photodissociation experiments taking place in a molecular beam. However, in some other cases, such as crossed molecular beam experiments, the large diameter (typically similar to 70 mm) of this conventional VMI lens can be inconvenient. We describe here a VMI lens with a much smaller diameter (down to similar to 20 mm) using tubular electrodes. The performance is evaluated by imaging O+ fragments produced by the photodissociation of O-2 at around 225 nm, and by inelastic scattering of NO with Ar. Our results suggest that the recorded images are of acceptable quality compared to those from a standard lens while achieving a fourfold reduction of the VMI lens diameter.

Automated summary

A VMI lens with a smaller diameter (around 20 mm) using tubular electrodes is described in this study, and its performance is evaluated in photodissociation and inelastic scattering experiments, showing acceptable image quality compared to a standard lens with a fourfold reduction in diameter.