Probing Multi-Electron Dynamics with Absolute Carrier-Envelope-Phase (CEP) Dependent Strong Field Interaction

Wayne State University, Detroit MI

Investigators

Abstract

General audience abstract: Atoms are made of equal numbers of electrons and nuclei and they are charge neutral. Therefore, they should not attract each other. However, it is well known that atoms can group together and form the most complex molecules that are indispensable for life, e. g., proteins and DNAs. The reason for this is because the correlated motions of many electrons can glue atoms together. This is called chemical bonding. If one can fully understand and control these motions, one can solve many practical problems such as making new molecules as cures for diseases. However, because the multi-electron nature of chemical bonding, the issue is very complex and challenging to tackle. In this project Professor Li and students at Wayne State University will use a very intense but well-controlled laser to rip one or two electrons from atoms and small molecules and watch how they interact with the rest of the electrons as well as the laser. This is a new way to study electronic motions and will offer unprecedented knowledge that might lead to novel control methods of chemical reactions. Additional benefit includes developing new laser technologies and training of the next generation of chemists and physicists. Technical audience abstract: In this project an important aspect of multi-electron dynamics - the multi-electron Coulomb potential, its interactions with departing electrons and the consequences of such an interaction in strong field ionization process - will be investigated. The major experimental approach is to use high performing ion-electron coincidence/covariance techniques coupled with few-cycle near infrared laser pulses (<5 fs). The properties of few-cycle pulses such as pulse duration, bandwidth and phase will be fully characterized. Specifically, Professor Li and his students aim to develop a new technique to determine the absolute carrier envelope phase (CEP) of linearly polarized few-cycle pulses for the first time without theoretical input. This will provide independent calibration of phase-dependent phenomena. Furthermore, the absolute CEP dependent data such as double ionization yields, electron momentum distributions and branching ratios of dissociative double ionization will be compared directly with the results of different theoretical modeling with and without the single active electron approximation (SAE) to reveal the importance of multi-electron dynamics in atomic and small molecular systems. The proposed research leverages cutting-edge experimental capabilities and will uncover new information on complex multi-electron dynamics. The research will also provide unprecedented tools for studying strong field dynamics. 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.