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J. Ullrich, A. Rudenko, Th. Ergler, B. Feuerstein, K. Zrost,
C.D. Schröter and R. Moshammer A series of time-resolved experiments is reported aiming to (i) map, characterize and finally to control ultra-fast nuclear motion in simple molecules and (ii) to study corre-lated sub-fs few-electron dynamics in strong-field multiple ionization. For that purpose, we have developed a unique combination of a 'reaction microscope' spectrometer imag-ing the complete final-state momentum space and a pump-probe setup providing two 7 fs, 1014 W/cm2 pulses at variable delays between 0 and 3300 fs, reaching absolute and relative precisions as good as 70 and 1 as, respectively. Via Coulomb explosion imaging we reconstruct the time-dependent probability density of the dissociating, rotating and vibrating nuclear wave-packets in the most fundamental molecular systems, the hydrogen and deuterium molecular ions. We observe the 'collapse' and 'revival' of their vibrational wave packets, investigate their composition via Fourier analysis, show novel routes to directly visualize field modified potential curves yielding a complete characterization of the field-induced ultra-fast molecular dynamics and, most recently, study the formation of H2+ ions in laser-induced fragmentation of methane. A one attosecond relative accuracy is demonstrated mapping the vibrational motion in the neutral D2 molecule and the corresponding excitation mechanism is iden-tified by determination of the absolute quantum phase of the motion. For multiple ionization of atoms recoil-ion momentum distributions allow us to distin-guish different ionization pathways and to reveal first time information on few-electron emission. For Ne we observe signatures of highly correlated recollision-induced three- and four-electron processes measured to occur on a 500 as time scale. |
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