Nonperturbative theory of femtosecond time-resolved spectroscopy: optical N-wave mixing and strong-pulse spectroscopies

• Applicant: Professor Dr. Wolfgang Domcke
• Subject Area: Theoretical Chemistry: Electronic Structure, Dynamics, Simulation ; Physical Chemistry of Molecules, Liquids and Interfaces, Biophysical Chemistry
• Term: from 2012 to 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 226726153

This research project aims at the further development of the theory of multiple-pulse UV/vis laser spectroscopy of polyatomic molecules. Deviating from the main-stream approach, which is based on the formalism of perturbative nonlinear optics, we elaborate a nonperturbative description of femtosecond time-resolved spectroscopy. In the weak-field regime, the nonperturbative theory is computationally more efficient than the traditional approach when applied to complex material systems. In the strong-field regime, there is no alternative to a nonperturbative description. We will investigate the potential of two-dimensional UV/vis spectroscopy and of polarization-sensitive pump-probe spectroscopy (two examples of four-wave-mixing spectroscopies) for the detection of ultrafast dynamics at conical intersections of electronic potential-energy surfaces. We will perform computational simulations of the signals of two novel six-wave-mixing spectroscopies (femtosecond stimulated Raman spectroscopy and heterodyned three-dimensional optical spectroscopy). We will develop a theoretical description of the novel and very promising technique of femtosecond double-pump single-molecule spectroscopy and will consider applications. We will explore to which extent strong-field phenomena, such as electronic Rabi cycling, can provide novel spectroscopic information on the ultrafast nonadiabatic dynamics of complex molecular systems.

• DFG Programme: Research Grants