The aim of this project will be to examine predictions of the hypothesis of our collaborator, Professor Alexandra Olaya-Castro (AOC), that the interplay between excitonic and vibrational motions is involved in maintaining long-lived coherence in photosynthesis complexes. A key, testable, prediction of the theory is that adding single mass units to atomic nuclei of key atoms in the pigments that are involved in vibrational coherence will shift the vibration frequencies to perturb coherence and thereby decrease the efficiency of energy transport. This project will build on an existing QB-DTC project to clone, express and purify bespoke photosynthetic complexes in E. coli, which will subsequently be investigated by a number of optical techniques including two-dimensional optical spectroscopy (2DOS). The aim of the current project to use metabolic approaches to add single mass units at particular atomic positions in pigment molecules that will thereafter be purified and examined by optical methods including Raman spectroscopy and 2D optical spectroscopy. The project will thereby test key predictions of the excitonic-vibrational coherence hypothesis.