Electron-ion coincidence momentum imaging of molecular dissociative ionization in intense laser fields: Application to CS2

An electron-ion coincidence momentum imaging apparatus has been developed and applied to dissociative ionization of CS2 in ultrashort intense laser fields. Photoelectron images of CS2 in 35 fs intense laser fields (2 x 1013 W/cm2, 800 nm, linearly polarized) recorded in coincidence with the parent ion, CS2+, show clear concentric ring patterns due to the above-threshold ionization (ATI) process. On the other hand, broad structureless distributions elongated along the direction of the laser polarization are observed in the coincidence electron images for the CS+ and S+ fragment ions. The difference in the electron images indicates that the dissociative ionization does not proceed sequentially by the formation and photodissociation of CS2+ in intense laser fields