Influence of the light excitation on energy transfer in a multi-pigments light-harvesting model of photosynthesis

Most studies on quantum effects in the process of excitation energy transfer in photosynthesis system arebased on the single-excitation initial state hypothesis, which can well describe the initial state of somephotosynthesis systems that people are concerned about. But for natural and artificial photosynthesis systemsthat do not meet the above hypothesis, the excitation process has a non-negligible impact on the systemdynamics. Based on a multi-pigments model excited by Gaussian pulse, the effects of the excitation pulse widthand the excitation interval on system dynamics and excitation energy transfer efficiency are studied. First, thekinetic equations for the overall evolution of the donor system and the acceptor system that can theoreticallycontain any number of pigments are derived. Afterwards, the relationship between the excitation energytransfer efficiency and the related parameters of the system, as well as the optimal range of the correspondingparameters are demonstrated by numerical simulation. It is found that under the condition of donor pigmentsbeing excited by a single Gaussian pulse, there exists optimal pulse width, and the optimal range of the pigmentmolecule numbers, the coupling strength as well as the dephasing rate can be modulated by the pulse width.The mechanism of the above modulation is also analyzed and presented. Under the condition of donor pigmentsbeing excited by two Gaussian pulses sequentially, there exists an optimal combination of pulse width and pulseinterval. The kinetic equations obtained in this paper can be extended to other forms of excitation pulses. Thenumerical results and the related optimal design principles obtained have reference significance for the optimaldesign of artificial photosynthesis systems under different light conditions.

Automated summary

This study investigates the effects of excitation pulse width and excitation interval on the system dynamics and excitation energy transfer efficiency of a multi-pigments model. The results show that there are optimal pulse width and parameter ranges for the system when the donor pigments are excited by a single Gaussian pulse. The mechanism of modulation is analyzed. Additionally, an optimal combination of pulse width and interval is found when the donor pigments are excited by two Gaussian pulses sequentially. The obtained kinetic equations and design principles have reference significance for the optimal design of artificial photosynthesis systems under different light conditions.