Imaging of oriented molecules

Hexapole state selection and orientation of parent molecules is combined with two-dimensional ion imaging of photofragments to study the direct photolysis of deuterated methyl iodide molecules (CD3I) at 266 nm. The combination of these two techniques allows us to create an essentially single quantum state-selected beam of oriented molecules, which are subsequently photodissociated, and to measure the final state-, velocity-, and angle-resolved recoil distribution of the photofragments. Extensive measurements have been done on the variation of the recoil distribution with the orientation field strength applied. These measurements allow a quantitative comparison of the orientation distribution of state-selected methyl iodide molecules with theoretical Stark effect calculations. For the prompt dissociation of CD3I at 266 nm the angular recoil distribution of the I(P-2(1/2)) photofragment reflects predominantly the initial spatial orientation of the state-selected parent. A comparison is presented between the fragment recoil distributions when different initial oriented parent states are selected.