Coincident Fragment Detection in Strong Field Photoionization and Dissociation of $H_2$

Electron-ion momentum spectroscopy is used to investigate the correlated electronic and nuclear motion in fragmentation of ${\mathrm{H}}_2$ in $4\times {10}^{14}\mathrm{W}/{\mathrm{cm}}^2$, 25 fs laser pulses at 795 nm. Reaction channel dependent photoelectron spectra indicate that besides the main, stepwise ${\mathrm{H}}_2$ ionization ${\mathrm{H}}_2^{+}$ dissociation mechanism resulting in the products $\mathrm{H}\left(1s\right)+{\mathrm{H}}^{+}{+e}^{-}$ a second new mechanism has to be assumed. The momentum distribution of ${\mathrm{H}}^{+}$ ions in the dissociation channels $\mathrm{H}\left(1s\right)+{\mathrm{H}}^{+}{+e}^{-}$ and $2{\mathrm{H}}^{+}{+2e}^{-}$ is found to be independent of the kinetic energy of the photoelectrons.