Many fundamental processes in nature (e.g. photosynthesis, catalysis, metabolism) result from the complex motion of an electron through the potential energy landscape defined by the positions of atoms constituting the polyatomic molecule. However, at the points of electronic degeneracy, called conical intersections, the simplistic Born-Oppenheimer approximation based energy landscape picture breaks down. Near such points the electron is at molecular crossroads and the result of the chemical process depends on the path chosen by the electron. We filmed the complex, coherent evolution of an electron hole near an conical intersection of an molecular ion using extreme ultraviolet, attosecond light bursts as a strobe light. We observe that the character of the electronic states becomes blurred near conical intersections.

We show that the presence of such an intersection in carbon dioxide molecule causes the electron hole distribution to oscillate back and forth within the molecule, and these quantum beats can persist for hundreds of femtoseconds. These results shed light on the question of how strongly electrons and nuclei influence each other during charge transfer reactions. From a technical viewpoint, this work establishes the attosecond spectroscopy as a powerful took for real-time study and control of electronic motion in complex molecules and materials.

Ultrashort XUV pulses can form highly-excited states, where the correlation effects play an important role during attosecond excitation and femtosecond fragmentation phases. Using the attosecond XUV pulses, synchronized with probe IR pulses; we aim to time-resolve the dynamics that occur within attoseconds to few femtoseconds of photon-molecule interaction. To image the photo-fragments we use two-dimensional detection scheme called velocity map imaging (VMI). We performed a direct measurement of the relaxation dynamics of neutral superexcited states of Oxygen. We investigated the competing predissociation and autoionization mechanisms for superexcited molecules and found that autoionization is dominant for the low n Rydberg states.