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Subject: Pump-probe spectroscopy ×

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    Time-resolved investigation of transient charges in laser-produced nanoplasmas
    (Bristol : IOP Publ., 2015) Schütte, Bernd; Vrakking, Marc J. J.; Rouzée, Arnaud
    We report on the observation of a transient C4+ ion charge state in nanoplasmas produced by the interaction of intense near-infrared (NIR) laser pulses with CH4 clusters. The underlying dynamics are studied by pump-probe spectroscopy, which reveals that the ion charge states are lowered by electron-ion recombination. Furthermore, we present direct evidence that autoionization of multiply-excited ions plays an important role in expanding nanoplasmas, in contrast to models that neglect quantum phenomena.
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    Terahertz radiative coupling and damping in multilayer graphene
    (Bristol : IOP, 2014) Bowlan, P.; Martinez-Moreno, E.; Reimann, K.; Woerner, M.; Elsaesser, T.
    The nonlinear interaction between intense terahertz (THz) pulses and epitaxial multilayer graphene is studied by field-resolved THz pump-probe spectroscopy. THz excitation results in a transient induced absorption with decay times of a few picoseconds, much faster than carrier recombination in single graphene layers. The decay times increase with decreasing temperature and increasing amplitude of the excitation. This behaviour originates from the predominant coupling of electrons to the electromagnetic field via the very strong interband dipole moment while scattering processes with phonons and impurities play a minor role. The nonlinear response at field amplitudes above 1 kV cm-1 is in the carrier-wave Rabi flopping regime with a pronounced coupling of the graphene layers via the radiation field. Theoretical calculations account for the experimental results.