Photofragmentation of Bin+/- clusters (n=2-19) in an electrostatic ion beam trap

Photofragmentation spectra for small bismuth-cluster cat- and anions are recorded for the investigation of their fragmentation pathways as a function of cluster size. To this end, the ions of interest are stored and size-selected in an electrostatic ion beam trap/a multi-reflection time-of-flight mass spectrometer with high resolving power. The subsequent photoexcitation is timed to their turn-around point in the trap's mirror potential. In this novel approach, charged fragment clusters exhibit the same energy as the precursor ions and, thus, can be further stored and investigated with identical trap configurations. The results suggest a high stability of the neutral bismuth tetramer in accordance with previous reports, which is attributed to bismuth clusters exhibiting semimetal properties. Additionally, there is evidence for the loss of larger neutral fragments.