Simultaneous 3D coincidence imaging of cationic, anionic, and neutral photo-fragments.

We present the design and simulations of a 3D coincidence imaging spectrometer for fast beam photofragmentation experiments. Coincidence detection of cationic, neutral, and anionic fragments involves spectrometer aberrations that are successfully corrected by an analytical model combined with exact numerical simulations. The spectrometer performance is experimentally demonstrated by characterization of four different channels of intense 800 nm pulse interaction with F ₂ ^- : F ^- + F photodissociation, F + F dissociative photodetachment, F ⁺ + F dissociative ionization, and F ⁺ + F ⁺ coulomb explosion. Improved measurement of F ₂ ^- photodissociation with a 400 nm photon allows a better determination of the F ₂ ^- anion dissociation energy, 1.256 ± 0.005 eV.