The Heisenberg’s uncertainty relation between energy and time restricts our ability to achieve high spectral and temporal resolution in a single experiment, although both are needed to investigate the ultrafast primary processes of photosynthetic light-harvesting. Two distinct experimental concepts providing either spectral or temporal resolution have been developed over the years.
We review their basic concepts together with a recent development of new techniques, namely the two-dimensional coherent electronic spectroscopy and the differential fluorescence line-narrowing being applied to the light-harvesting complexes. Extensive collaboration between the Charles University in Prague and the Lund University in Sweden makes it possible to investigate bacterial reaction centers as well as artificial bacteriochlorophyll c aggregates, taking advantages of the both above mentioned techniques.
Future prospects for acquiring new knowledge about the recently observed quantum coherence effects in the light-harvesting are discussed.