Title: Probing ultrafast non-Born-Oppenheimer dynamics in molecules with two-color femtosecond x-ray pulses. Speaker: Ali Belkacem, Lawrence Berkeley National Laboratory Time: Monday, October 10, 11.15 to 12.00 Place: 1525-323 NOTE: not in Phys. Aud.! Abstract: I will start my talk with a brief overview of the on-going work on ultrafast science within the Ultrafast X-ray Science Laboratory (UXSL) at Lawrence Berkeley National Laboratory (LBNL). I will then describe my own research using various x-ray sources including synchrotron radiation at the Advanced Light Source, high intensity high harmonic sources and FELs. This body of work, using different x-ray sources, allows us to tackle dissociation dynamics of molecules both from the energy domain and the ultrafast time-domain. In this talk I will focus on studies in the time domain of non-Born-Oppenheimer dynamics and isomerization in prototypical systems such as ethylene and acetylene using a femtosecond high intensity high harmonic source. Over the last decade, a picture of photochemistry has emerged in which conical intersections between different electronic states provides an efficient ?funnel? decay of electronic energy. But before a photo-excited system can undergo internal conversion through a conical intersection, the molecule must first rearrange to find it. Ethylene is the simplest molecule with a carbon double bond, yet even this simple case exhibits rich internal conversion dynamics. I will show how a combined experiment-theory approach allows to access unique information about the transition through a conical intersection. Jacob Sherson and Aurélien Dantan Coffee, tea and cake will be served at 11.05 Dr. Jacob Friis Sherson Department of Physic and Astronomy Aarhus University Ny Munkegade 120 8000 Århus C Denmark Tel.:+45 8942 3680