Imaging Techniques in Experiments on Dynamics

Spatial distributions of dynamic systems with resolved translational energy and selected internal states provide indispensable information about the corresponding physical and chemical mechanisms. From an experimental viewpoint, two‐dimensional imaging techniques are well suited to explore dynamic aspects of collisional processes. The advantages of imaging techniques over conventional methods are demonstrated in laser ablation of metal targets and collisionally induced electronic excitation of metal atoms. Approaching the ultimate goal in chemical dynamics, a unique method which combines laser‐induced fluorescing illumination and gated two‐dimensional imaging techniques can directly measure the three‐dimensional distributions of number density, angle and velocity of scattered products from photofragmentation and from inelastic and reactive collisions in the center‐of‐mass frame. The physical principle behind this direct method and its experimental arrangement are outlined.