Few-femtosecond passage of conical intersections in the benzene cation.

Observing the crucial first few femtoseconds of photochemical reactions requires tools typically not available in the femtochemistry toolkit. Such dynamics are now within reach with the instruments provided by attosecond science. Here, we apply experimental and theoretical methods to assess the ultrafast nonadiabatic vibronic processes in a prototypical complex system-the excited benzene cation.

Stark-assisted quantum confinement of wavepackets. A coupling of nonadiabatic interaction and CW-laser.

When a nonadiabatic system that has an ionic state (large dipole moment) and a covalent state (small dipole moment) is located in a strong laser field, the crossing point of the two potential energy curves is forced to oscillate due to the oscillating laser field and to meet wavepackets moving on the potential curves many times. This leads to additional transitions between the two states, and under favorable conditions, the wavepacket may be confined in a spatial region rich in nonadiabatic interaction. In this paper, taking the LiF molecule system in a continuous-wave driving field as a prototypical example, the dynamical origins of the wavepacket confinement are theoretically investigated.

Induced photoemission from driven nonadiabatic dynamics in an avoided crossing system.

When vibrational dynamics on an ionic state (large dipole moment) is coupled to that on a neutral state (small dipole moment) such as at an avoided crossing in the alkali halide system, the population transfer between the states cause oscillation of the molecular dipole, leading to dipole emission. Such dynamics may be driven by an external field. We study how the coupled wavepacket dynamics is affected by the parameters (intensity, frequency) of the driving field with the aim of making use of the photoemission as an alternative detection scheme of femtosecond and subfemtosecond vibrational and electronic dynamics or as a characteristic optical source.

Control scheme of nonadiabatic transitions with the dynamical shift of potential curve crossing.

We investigate how the nuclear dynamics at an avoided crossing is affected and can be controlled by the introduction of a laser field whose cycle is comparable to the time-scale of the nuclear dynamics. By introducing the concepts of light-induced effective potential energy curves and dynamical avoided crossing, we describe the laser controlled nuclear dynamics and present basic control scenarios, giving a detailed explanation of the underlying dynamical mechanisms. The scenarios presented allow for examples to understand from a different perspective the results of dynamic Stark control experiments.

Time-resolved measurement of interatomic coulombic decay in Ne2.

The lifetime of interatomic Coulombic decay (ICD) [L. S. Cederbaum et al.