BEGIN:VCALENDAR VERSION:2.0 PRODID:Icfo X-PUBLISHED-TTL:P1W BEGIN:VEVENT UID:69d255b846ea9 DTSTART:20230313T090000Z SEQUENCE:0 TRANSP:OPAQUE LOCATION:Auditorium and Online (Teams) SUMMARY:ICFO | STEFANO SEVERINO CLASS:PUBLIC DESCRIPTION:One of the fundamental goals of the physical chemistry communit y has always been to be able to follow the details of the evolution of che mical reactions in real-time. Besides the extreme temporal resolution (sub -femtoseconds) required\, a blurred picture of the dynamics often arises f rom the difficulties of spectroscopically disentangling the interplay betw een the electronic and nuclear degrees of freedom in complex compounds. Th is depends on the observable used for the experiments\, which defines the direct and indirect information that can be retrieved. For example\, elect ron diffraction or X-ray scattering methods directly track the structural changes of a species during a reaction. X-rays Absorption Fine Structure ( XAFS) spectroscopy\, instead\, follows the dynamics from the electron pers pective by probing transitions from a core orbital to an empty valence orb ital. Especially when applied to the soft X-ray wavelength region\, the co re-hole transitions minimize the spectral congestion and provides inherent element\, charge and state sensitivity. At the same time\, the observable is strongly dependent on the geometrical changes and\, hence\, provides i nformation regarding the nuclear dynamics.\nWith the emergence of attoseco nd science\, the remarkable properties of XAFS spectroscopy were combined with unprecedented temporal resolution matching the natural timescales of electronic motion in matter. This equipped the scientific community with a tool capable of disentangling the details of the intricate dynamics that arise from the interaction between light and matter\, and initiated a revo lution in the field of ultrafast spectroscopy. Among the many chemical dyn amics that can be investigated\, Attosecond XAFS (AttoXAFS) spectroscopy i s very appealing for the study of non-adiabatic processes of polyatomic sy stems involving degeneracy points of the potential energy surfaces\, i.e.\ , conical intersections (CIs)\, in which electronic and vibrational cohere nce play a crucial role. In these phenomena\, the ability to disentangle t he nuclear and electronic degrees of freedom is fundamental for a correct interpretation of the process.\nIn this thesis\, AttoXAFS in the soft X-ra ys is applied to the study of the complex non-adiabatic dynamics of a prot otypical heterocyclic molecule\, furan. Analysis of the experimental data\ , with the support of high-level simulations\, provides a clear interpreta tion of the ultrafast coupled electron and nuclear dynamics. The temporal resolution and sensitivity to both electronic occupancies and structural c hanges allow following the dynamics step by step\, revealing information a bout the nuclear and electronic configuration of the molecule with an unpr ecedented level of detail. The resulting picture shows how the passage thr ough subsequent CIs defines the flow of the electronic population through transient dark states and the complete relaxation to the ground state\, as well as the interplay between electronic and vibrational coherence dynami cs.\nIn chapter 1 of this thesis\, I will provide the framework for these results. This consists\, on the one hand\, of the recent development of at tosecond science and its achievements in the study of light-matter interac tion and\, on the other\, the coupled nuclear and electronic dynamics that characterize the photoinduced chemical reaction of polyatomic systems. In chapter 2 I will present the experimental setup developed in Prof. Dr. Je ns Biegert&rsquo\;s lab with which the results of this thesis were obtaine d. In chapter 3\, I will discuss the importance of high photon energy puls es for materials science\, focusing on XAFS and its capabilities\, and sho w its exemplary applications on various solid state and gas phase samples achieved during my PhD. The core of this thesis is presented in chapter 4\ , where I will describe the experimental data on furan and the main result s of the combined theoretical and experimental investigation. Finally\, I will conclude with a summary and an outlook.\n \;\nThesis Director: Pr of Dr. Jens Biegert DTSTAMP:20260405T122944Z END:VEVENT END:VCALENDAR