Ion Imaging

Ion imaging, developed at the CRF by Dave Chandler and Professor Paul Houston of Cornell University in 1987, is a technique for determining the velocity distribution (speed and angle) of molecules or molecular fragments and then using that distribution to deduce the dynamic properties of the parent molecule. In the first ion-imaging experiments, laser-induced dissociation products were state-selectively ionized, allowed to drift for a period of time, then subsequently detected on a two-dimensional array. Ion imaging has found many uses, often as a diagnostic probe on varying experiments. From the first study of the unimolecular dissociation of CD₃I to the more recent determinations of differential cross sections of collisional bimolecular reactions and velocity mapping, the technique continues to evolve. Most recently, in the Chemical Dynamics Visitor's Research Laboratory, ion imaging together with a crossed molecular-beam apparatus has been used to measure the differential cross sections of collisional energy transfer between HCl and the alignment and orientation of NO after collision with argon.