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Aufsatz
Femtosecond two-photon ionization spectroscopy of the B state of Na_3 clusters
(1993)
We report time-resolved experiments studying the dynamics of the Na_3 B-X system. Femtosecond pump-probe techniques combined with ion time-of-flight (TOF) and zero kinetic energy (ZEKE) photoelectron spectroscopy allow us to observe the three-dimensional wavepacket motion in the excited Na_3 B state and in the Na_3 X state. The ground state wavepacket is induced by stimulated emission pumping during the pump pulse. The X-state dynamics is dominated by the three vibrational modes of the Na_3. Furthermore we observed ...
Aufsatz
High laser field effects in multiphoton ionization of Na_2
(1992)
Femtosecond pump/probe multiphoton ionization experiments on Na_2 molecules are performed. The dependence of the total Na^+_2 ion signal on the delay time and the intensity of the femtosecond laser pulses is studied in detail. It is observed that molecular vibrational wavepacket motion in different electronic states dominates the time dependence of the ion signal. For higher laser intensities the relative contributions from the A ^1 \summe^+_u and the 2 ^1 \produkt__g states change dramatically, indicating the ...
Aufsatz
Molecular photochemistry with femtosecond laser pulses
(1990)
Femtosecond laser pulses generated from an amplified coiliding pulse modelocked ring dye laser have been employed in molecular beam experiments to study the dynamics and the pathways of multiphoton induced ionization, autoionization and fragmentation of Na2 . Energy distributions of photoelectrons arising from these processes and the mass and released kinetic energy of the corresponding fragment ions are measured by time-of-flight spectroscopy.
Aufsatz
Time-resolved studies of neutral and ionized Na_n clusters with femtosecond light pulses
(1993)
The real-time dynamics of Na_n (n=3-21) cluster multiphoton ionization and fragmentation has been studied in beam experiments applying femtosecond pump-probe techniques in combination with ion and electron spectroscopy. Three dimensional wave packet motions in the trimer Na_3 ground state X and excited state B have been observed. We report the first study of cluster properties (energy, bandwidth and lifetime of intermediate resonances Na_n^*) with femtosecond laser pulses. The observation of four absorption resonances ...
Aufsatz
Femtosecond pump-probe study of the spreading and recurrence of a vibrational wave packet in Na_2
(1992)
The motion of a vibrational wave packet in the bound A(^1 \summe^+_u) electronic state of the sodium dimer is detected in a femtosecond pump/probe molecular beam experiment. For short times harmonic motion is seen in the total ion yield of Na^+_2 as a function of delay time between the two laser pulses. The spreading of the wave packet results in the loss of the periodic variation of the ion signal. For longer delay times (47 ps) the wave packet regains its initial form which is reflected in the revival structure of ...
Aufsatz
Femtosecond time-resolved molecular multiphoton ionization: the Na_2 system
(1991)
We report here the first experimental study of femtosecond time-resolved molecular multiphoton ionization.
Femtosecond pump-probe techniques are combined with time-of-flight spectroscopy to measure
transient ionization spectra of Na_2 in a molecular-beam experiment. The wave-packet motions in
different molecular potentials show that incoherent contributions from direct photoionization of a singly
excited state and from excitation and autoionization of a bound doubly excited molecular state determine
the observed ...
Aufsatz
Autoionization and fragmentation of Na_2 studied by femtosecond laser pulses
(Ed. by Michael S. Feld u.a., 1989)
Aufsatz
Femtosecond probing of sodium cluster ion Na_n ^+ fragmentation
(1992)
We report on the first femtosecond time-resolved experiments in cluster physics. The photofragmentation
dynamics of small sodium cluster ions Na_n ^+ have been studied with pump-probe techniques. Ultrashort
laser pulses of 60-fs duration are employed to photoionize the sodium clusters and to probe the
photofragments. We find that the ejection of neutral dimer Na_2 and, observed for the first time, neutral
trimer Na_3 photofragments occur on ultrashort time scales of 2.5 and 0.4 ps, respectively. This and the
absence ...
Aufsatz
Femtosecond spectroscopy of molecular autoionization and fragmentation
(1990)
Femtosecond laser pulses are applied to the study of the dynamics and the pathways of multiphoton-induced ionization, autoionization, and fragmentation of Na_2 in molecular-beam experiments. In particular,
we report on first results obtained studying electronic autoionization (leading to Na_2{^+} + {e ^-}) and
autoionization-induced fragmentation (leading to Na{^+} + Na + {e ^-}) of a bound doubly excited molecular state. The final continuum states are analyzed by photoelectron spectroscopy and by measuring the ...