  Fluorescence-detected two-dimensional electronic spectroscopy (F-2DES)
projects the third-order non-linear polarization in a system as an excited
electronic state population which is incoherently detected as fluorescence.
Multiple variants of F-2DES have been developed. However, none have
demonstrated analysis of kinetics and coherences routine in photon-echo 2DES.
Here, we report phase-modulated F-2DES measurements on a strongly coupled
symmetric bacteriochlorin dyad, a relevant 'toy' model for photosynthetic
energy and charge transfer. Coherence map analysis shows that the strongest
frequency observed in the dyad is well-separated from the excited state
electronic energy gap, and is consistent with a vibrational frequency readily
observed in bacteriochlorin monomers. Kinetic rate maps show a picosecond
relaxation timescale between the excited states of the dyad. To our knowledge
this is the first demonstration of coherence and kinetic analysis using any
variant of F-2DES.
