Excitation energy transfer between monomeric bacterioclorophylls in reaction centers of P-less mutant of purple photosynthetic bacteria.

Excitation energy transfer between bacteriochlorophyll monomers in mutant bacterial reaction centers occurs within 104–98 fs, revealing close pigment interactions.

• Why it matters: Understanding these ultrafast dynamics is crucial for deciphering the physical mechanisms of natural photosynthesis and designing artificial light-harvesting systems.
• What they did: Using femtosecond differential absorption spectroscopy, the study examined excitation shifts in B A and B B monomers of mutant RCs from Rhodobacter sphaeroides, lacking the P dimer, across different wavelengths and temperatures.
• The result: Findings show rapid, reversible energy transfer between B A and B B with rates increasing at lower temperatures, indicating a tightly coupled pigment network that influences excitation dynamics.