Theoretical Studies of Ultrafast Electron Dynamics in Molecules Interacting with Intense Laser Pulses

The ability to capture and control in real time the rearrangement and motion of electrons is considered a grand challenge in physics, chemistry, and biology. Ultrashort laser pulses allow for direct probing of the transient properties of (quantum) matter on the natural time scales of its quantum evolution. The present project is directing toward providing theoretical insights into how to identify, understand, and control changes in the electron wavepacket dynamics and rearrangements in the quantum electron density in molecules during laser-induced processes.

Theoretical studies within this project are motivated by recent breakthroughs in making measurements at the attosecond (one quintillionth of a second) time scale and will support experiments that study the molecular ionization process under the impact of high-intensity laser fields, high-order harmonic generation that produces high-energy electromagnetic radiation, and ultrafast multi-electron dynamics in molecules.

One of the central goals of the present project is to apply methods that describe the time evolution of the electronic wavepacket including both ground and excited states as well as continuum. Ab initio numerical simulations within time-dependent density functional theory will explore the properties of quantum dynamics during the sharing and migration of electrons between participating atoms in a molecule.

Of particular interest is the connection between nonadiabatic electron localization features in the dynamics and the unique signatures present for molecular superposition states for nonlinear processes such as intense field ionization and high harmonic generation. (Bi)-circularly polarized laser pulses offer a way to control and explore the ring current related dynamics where a circularly-polarized light pulse transfers its chirality to the molecule, which is manifested in either clockwise or counter-clockwise current. The intellectual merit of the research project arises from the combination of theoretical and numerical challenges, present when attempting the solution of the many-body problem in an external field of nonperturbative strength, and numerical simulations of time-dependent highly nonlinear processes.

The results of the project are envisaged to contribute to understanding the photophysical processes occurring in molecular systems in the presence of intense laser fields and attosecond science. Studies within this project will be directly relevant to experimental work performed to study strong laser field ionization and high order harmonics generation devoted to uncovering the details of electron dynamics occurring in simple and complex systems.

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.