Figure 1
(a) Sketch of a molecular interferometer: we use as reference the ionization signal retrieved upon interaction with a single pulse. This interaction leads to ionization, but it also excites the molecule. The excitation dynamics however can only be captured by introducing a second pulse (probe). A series of experiments introducing a second pulse with different time delays (\(\tau _1\), \(\tau _2,\ldots \)) with respect to the first one is then performed. The probe pulse can ionize from the ground state or from the coherently populated excited states. Optical and quantum interferences are then imprinted in the measurable ionization signal. The electron wave packet created upon ionization by the pump pulse alone (i.e., our reference wave) interfere with the one resulting after the interaction with the probe, thus imprinting the information of the excitation dynamics in our signal. (b) Schematic representation of the energetics and the attosecond pump-probe scheme using 2-fs pulses with a carrier frequency of 14 eV. The interaction with the pump pulse creates a wave packet with components in the ground, excited (through 1-photon absorption) and ionized molecule (through 1 and 2-photon absorption processes). We include the realistic distributions of the nuclear wave packet components for pump and probe pulses with 2-fs duration, \(T_1=T_2=2\) fs, and a time delay \(\tau \) between them of 6 fs. (c) The interaction with the probe pulse creates a replica of the wave packet generated by the identical pump pulse, but also induces ionization from the evolving wave packet in the excited molecule.
