270170 VO Principles of Two-Dimensional Electronic Spectroscopy (2012S)

The Lectures will survey a broad class of coherent spectroscopic techniques and address tools and theoretical microscopic descriptions for the interpretation of non-linear observables in the study of complex molecules, biological systems, and selected semi-conductors. Experiments include excitation/probing with a sequence of laser-pulses with controllable inter-pulse relative phase, tuning-frequency and widths, and from the theoretical point-of-view, the development and design of formalisms suitable to cover molecular features such as electronic/nuclear motions) to establish, systematically, spectroscopy in polarization- (coherent regime) and population space (incoherent regime).
With the culmination of two-dimensional Fourier-Transform (FT) electronic spectroscopy (2D-ES), cutting edge experiments have emerged that probe molecular correlations on the 500 THz scale of the electronic transition dipole oscillation, thereby recording the diffracted molecular Four-Wave-Mixing - electrical field both under controlled phase at the amplitude level and along two frequency axes via double FT. In particular, the cross-peaks carrying the off-diagonal signals are directly sensitive to the presence of molecular quantum-interference and coherent phenomena. This has led, over the past few years, to exciting prototypical studies on electronic oscillators in biological light harvesting complexes and, in later experiments, to investigations on artificial aggregates by directly probing electronic coupling, quantum-oscillatory motion, and non-perturbative exciton dephasing.
From the theoretical point-of view, a correlation-function framework for computing NL optical signals will be introduced using superoperator techniques for describing the measurements via the evolution of the density-matrix in terms of the various Feynman quantum-pathways in Louville-space. Connection between multi-point correlation and optical response-functions will be established and the relationship between various FT-projections in multi-dimensional correlation spectroscopies will be surveyed. Very recent experimental highlights of 2D- spectroscopic science will be demonstrated from ground-breaking studies on excitonic (organic and semi-conductor) nanostructures, conjugated polymers, proteins, biological & synthetic aggregates , hydrogen bonded liquids and related bio-functional molecular systems