Uncovering Non-Adiabatic Dynamics in Strong Field Molecular Ionization

This work will study how electrons and nuclei move inside of molecules. Observing such motion will advance physicists' understanding of many processes in nature such as vision, energy storage, energy conversion, and chemical transformation. It is also important for fundamental approaches to the development of new technologies such as solar cells, ultrafast molecular switches, and quantum computers. While lasers are natural tools for manipulating and measuring electrons in molecules, one requires very short laser pulses in order to manipulate electrons in real time. The investigators in this project will use intense ultrashort laser pulses in order to ionize molecules, removing one of the many electrons bound to the molecule. They will take pictures of the electrons as they come off the molecules, making use of a technique called velocity map imaging. These pictures can be used to understand the coupled dynamics of electrons and nuclei during ionization, which is important for understanding chemical dynamics and for developing high speed electronics. This project will make use of shaped few cycle laser pulses to study non-adiabatic and correlated strong field ionization of small molecules (~5-10 atoms). The investigators will control the shape of sub 10 fs (3-4 optical cycles) laser pulses, and make use of velocity map imaging in order to study the angle and momentum resolved photoelectron spectrum (in coincidence with fragment ions) as a function of laser pulse shape. This will help develop a deeper understanding of how electrons are removed from multiple orbitals, and the extent to which electron correlation and non-Born Oppenheimer dynamics play a role in the ionization dynamics. The investigators will also make use of strong field ionization as a probe of excited state dynamics, studying dissociation and internal conversion in families of homologous molecules in order to understand similarities and differences. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.