Ultrafast dynamics in polyatomic molecules on the attosecond and femtosecond time scale

Ultrafast dynamical processes in molecules are determined by subtle effects such as electron correlation and non-adiabatic couplings that are, beyond textbook cases of quantum mechanics, responsible for many mechanisms in natural and synthetic systems. With the emergence of ultrashort XUV pulses it has become possible to excite or probe valence electrons in molecules and to reveal the role of electron-ion entanglement, electron correlation and non Born-Oppenheimer effects on ultrashort timescales possibly reaching the attosecond domain.
In this talk we will describe recent experiments where XUV pulses that are synthetized with the help of high harmonic generation, have been used to track light induced time-dependent molecular dipoles on the attosecond times scale, offering the possibility to control molecular photoionization and to probe dynamical variations of the electron density on atomic length scale. We will show that XUV pulses can also generate excited states for which electron correlation and non-adiabatic couplings play an essential role on very short time scales in relevance with astrochemistry.