From non-sequential to sequential strong-field multiple ionization: identification of pure and mixed reaction channels

Momentum distributions of Ne 3–4+ ions created by 795 nm, 25 fs laser pulses have been measured at 10 15 –2 × 10 16 W cm −2 using a 'reaction microscope' in order to characterize the transition regime between non-sequential and sequential strong-field ionizations. We can clearly separate pure and/or mixed recollision-induced (e, n e)-like reactions and sequential (field-induced) processes, and observe transition intensities which agree with recently reported ion-yield data. Our results provide consistent qualitative description of Ne strong-field multiple ionization for all non-relativistic intensities.