Ultrafast Molecular Dynamics probed by Vacuum Ultraviolet Pulses

We present time-resolved measurements of the relaxation dynamics in small molecular systems (CO$_2$ and C$_2$H$_4$) following ultraviolet~(UV) photo-excitation. We probe these excitations through photoionization and velocity map imaging~(VMI) spectroscopy. Vacuum and extreme ultraviolet (VUV/XUV) pump and probe pulses are created by exploiting strong-field high harmonic generation~(HHG) from our state-of-the-art 30~mJ, 1~kHz laser system. Three dimensional photoelectron and photoion momentum images recorded with our VMI spectrometer reveal non-Born Oppenheimer dynamics in the vicinity of a conical intersection, and allow us track the state of the system as a function of time. We also present initial experiments with the goal of controlling the dynamics near a conical intersection using a strong-field IR pulse. Finally, we will show progress towards measurements of time-resolved molecular frame photoelectron angular distributions~(TRMFPADs) by applying our VUV/XUV pulse sequence to an aligned molecular ensemble.