Coherent 2D spectroscopy

This technique has the following projects (and possibly other techniques) related to it:

• 2D spectroscopy of astaxanthin in solution and in carotenoprotein crustacyanin
• 2D spectroscopy studies of coupling and energy transfer in light-harvesting complexes of marine organisms

To understand the function of the molecules and complex molecular systems, complementary information about structure and dynamics is required. Two-dimensional (2D) femtosecond spectroscopy in the visible and infrared (IR) spectral regions has a potential to revolutionize understanding of complex molecular systems. 2D spectroscopy measures polarization evolution of the system that carries information about the population and coherence dynamics of excited molecules. Even more importantly, it provides direct information about intermolecular couplings, which are directly related to the molecular structure. In addition, the multidimensional spectroscopy presents a window into immediate molecular environments and intramolecular geometries that are frozen on femtosecond time scale, thus allowing to peek under the ensemble average exposing the fundamental properties of molecules and their interaction with the environment. Using the information of intra-complex interactions and dynamics combined with rigorous theoretical modeling and available static structure allows determining spatio-energetic distribution of chromophores and gaining a deeper understanding of ultrafast photophysical and photochemical processes.

Hypothetical 2D spectrum

Diagonal peaks correspond to linear spectrum. Cross peaks and asymmetry of the 2D spectrum show couplings between electronic excitations. Shape of the 2D spectrum reveals distribution of the environments.

Coherent 2D spectroscopy features

• The most comprehensive femtosecond nonlinear optical spectroscopy technique to date.
• Enables direct measurement of electronic coupling and energy transfer pathways on the energy landscape leading to dynamical structure information.
• Allows observation of the coherence dynamics effects.
• Complementary spectral and temporal resolution is not limited by the uncertainty principal of the laser pulse leading to unprecedented richness of functional detail.

Using 2D electronic spectroscopy we are going explore electronic couplings and energy transfer pathways of an array of natural and artificial photosynthetic complexes.