Femtosecond Dynamics and Multiphoton Ionization driven with an Intense High Order Harmonic Source

We have constructed a high intensity high order harmonic source at the Lawrence Berkeley National Lab delivering $\sim $10$^{9}$ extreme ultraviolet photons/shot on a gas target and used it to observe multiphoton ionization and conduct femtosecond EUV-pump IR-probe experiments. Following excitation by 20-25 eV photons, we observed that the excited ethylene cation (H$_{2}$C-CH$_{2})^{+}$ experienced isomerization to the ethylidene configuration (HC-CH$_{3})^{+}$ in 50$\pm $25 fs, followed by an H$_{2}$ stretch motion. Experimental data and analysis from several experiments as well as a future outlook of our efforts will be presented.