New theory and computational methods are crucial to unlock the full potential of new ultrafast experiment soon to be made possible by light sources currently under construction, such as the European XFEL in Hamburg and the LCLS in Stanford. This proposal focuses on ultrafast diffraction imaging, either by x-rays or electrons, and a new intense-laser technique, high harmonic spectroscopy.
The distinct advantage of diffraction based techniques is that they allow a direct interpretation of molecular dynamics in terms of the motion of atoms, while the high harmonic spectroscopy is spectacularly sensitive to the electronic changes that accompany chemical transformations and which often govern the outcome of photochemical reactions. In short, these two sets of techniques have the potential to revolutionize our ability to observe and control photochemistry and ultrafast dynamics, but the theoretical tools to interpret them are missing. I will develop these tools and significantly advance the state-of-the-art in quantum simulations by making realistic start-to-finish simulations of the experiments possible. This can only be achieved by adapting cutting-edge techniques from atomic, molecular and optical physics.