Multidimensional femtosecond correlation spectroscopies of electronic and vibrational excitons

Four two-dimensional (2D) four-wave-mixing techniques that can be used to extract information about structure and coupling patterns of interacting chromophores are proposed. These techniques have close conceptual similarities with multiple-pulse NMR spectroscopies. Closed expressions for the signals are derived by solving the nonlinear exciton equations (NEE) which describe the dynamics of multiple excitations using the one-exciton Green function and the exciton-exciton scattering matrix. Possible applications include electronic spectroscopy of aggregates, e. g., photosynthetic antenna complexes, and infrared spectroscopy of localized vibrations (e. g., amid bands in polypeptides). Model calculations are presented for three-chromophore aggregates. (C) 1999 American Institute of Physics. [S0021-9606(99)01011-9].