An Implementation of General Polarization-Resolved Two-Dimensional Electronic Spectroscopy

Two-dimensional electronic spectroscopy (2DES) is a powerful tool to study the dynamics of complex molecular systems. Polarization control in 2DES allows enhancement of selective signals, providing information about the transition dipole orientations and rotational motion. In this work, we discuss an implementation of polarization-resolved 2DES (p-2DES) in the pump-probe beam geometry that simultaneously acquires signals under parallel and perpendicular pump-probe polarizations. This approach is general, as these two sets of signals can be combined as desired to obtain 2DES spectra of various polarization schemes, such as magic angle, cross-peak specific, diagonal-peak enhancing, and anisotropy. We demonstrate the approach using (1) phthalocyanine, a molecular system with two orthogonal electronic transitions and (2) the photosynthetic light-harvesting complex II, which exhibits a highly congested spectrum with many concurrent energy transfer processes. We show how the polarization schemes can help resolve hidden spectral and kinetic features. This implementation can help to streamline the use of p-2DES and provide more insights into the structural and dynamical properties of complex systems.