Mass-selected Ion-molecule Cluster Beam Apparatus for Ultrafast Photofragmentation Studies

We describe an apparatus to study the fragmentation of iodide-molecule clusters triggered by laser excitation and transfer of an electron from the iodide to the neutral molecule. The instrument captures both charged and neutral fragments. The apparatus comprises a source to generate the ion-molecule clusters, a time-of-flight (TOF) spectrometer and a mass filter to select the desired anions, and a detection chamber where the laser excites the clusters and the fragment anions and neutrals are captured. The apparatus performance is tested by measuring the photofragments: I^-, CF₃I^- and neutrals from photoexcitation of ion-molecule cluster CF₃I·I^- using 266 nm UV laser.The experimental results are compared with recent experiments and calculations, with particular attention to the dynamics of the photoexcitation.