Before revision:  Despite its importance, the physical principles that underpin the primary steps of photosynthesis , from photon absorption to electronic charge separation, remain to be understood in full. Previously, electronic coherence within tightly-packed light-harvesting (LH) units or within individual reaction centers (RCs) has been recognized as an important ingredient for a complete understanding of the excitation energy transfer dynamics.
After revision:  Despite its importance, the physical principles that underpin the primary steps of photosynthesis involve the photo-excitation of reaction centres (RCs) has been recognized as an important ingredient for a complete understanding of the excitation energy transfer dynamics.