T. Frohnmeyer et T. Baumert, Femtosecond pump-probe photoelectron spectroscopy on Na-2: a tool to studybasic coherent control schemes, APP PHYS B, 71(3), 2000, pp. 259-266
Femtosecond pump-probe photoelectron spectroscopy has become a common tool
in ultrafast gas-phase science because of its sensitivity both to structura
l and electronic changes in a molecule upon excitation. Here a summary and
extended discussion of our experiments is presented. We focus on the potent
ial of this method to study basic femtosecond coherent control schemes. Mul
ti-photon excitation of the Na-2 molecule with femtosecond laser pulses lea
ds to preparation of vibrational wave packets. Mapping of the vibrational w
ave-packet dynamics by time-resolved photoelectron spectroscopy offers the
high spatial and temporal resolution required to investigate a variety of l
aser-control parameters in great detail. Besides an illustration of the Tan
nor-Kosloff-Rice scheme we demonstrate electronic transitions at Franck-Con
don forbidden internuclear distances due to the intensity of the applied la
ser pulses. Further we discuss the influence of simple phase-modulated (lin
early chirped) laser pulses on a molecular multi-photon process. An enhance
d population transfer is derived due to synchronization of the wave-packet
motion on an electronic potential to an appropriate chirp of the laser puls
es. In addition, the influence of the temporal profile on the population tr
ansfer and the role of the pulse duration are studied.