Femtosecond Laser Induced Energy Transfer Kinetics Between Pigment Molecules Of Ps Ii

Study on the mechanism of photosynthesis is always a compelling research field in the world. In China, it was listed into the State Key Basic Research and Development Plan ("973") with a definite goal to serve for the Sustainable Agriculture. Elucidation of the photosynthesis mechanism will provide important theory supply for enhancing efficiency of light energy utilize, increasing crop yield in acreage of unit and even simulating photosynthesis to synthesize food.Transient state and steady state fluorescence spectroscopy technology, time-resolved difference absorption spectroscopy technology had been used to study the energy transfer kinetics between the pigments of photosystem II in photosynthesis.The main works were described as the following:1 Molecule mechanisms of energy absorption and transfer in photosynthesis and three mechanisms of excitation energy transfer were universally dissertated. The previous results of the structure and components of PS II and its function units were summarized.2 Measurement principles of transient and steady state fluorescence spectroscopy technology and time-resolved absorption difference spectroscopy technology were expatiated. According to the compare results among several methods on data processing , using Metlab program , software of data processing was designed3 The femtosecond time-resolved transient and steady state fluorescence spectrophotometer with great performance features was integrated and established successfully. The excitation laser can be tuned in super wide range, from 300 nmto 3 U m. The time and spectral resolutions are about 30 ps and 0.5 A. In addition, polarizer and liquid nitrogen low temperature controller are appended, which extend the research field. These are the specialties of the instrument.4 The femtosecond time-resolved absorption difference spectrophotometer was established innovatively, of which the time resolution is very high to 100 fs or so. Its pump beam is super wide harmonious laser pulse, and probe beam is white light pulse. Using the instrument to study sample, we can obtain more information.5 The femtosecond time-resolved transient and steady state fluorescence spectrophotometer was carried out and at 83k, the fluorescence spectral properties of LHCII excitated at 436 and 507 nm were studied, respectively.6 Using the femtosecond time-resolved transient and steady state fluorescence spectrophotometer, at 273k, fluorescence spectral properties and time properties of LHC II excitated at 507nm was studied and six spectral analytical components and three energy transfer time components were obtained and ascribed. Furthermore, the theory of exciton transform mechanism was used to calculate energy transfer time constant between adjacent chlorophylls. The calculation is in agreement with experiment result.7 Spectral and energy transfer properties of homotrimer and heterotrimer of LHC II from Bryopsis Corticulans were firstly studied and compared by the super-wide harmonious femtosecond time-resolved fluorescence spectroscopy instrument. Four and five spectral properties of characteristic pigments were obtained from homotrimer and heterotrimer, respectively. Energy transfer lifetimes of 165 ?.5fs, 2.2?.6ps, and 5.1 ?.1ns of Chi molecules from homotrimer were obtained by fitting fluorescence decays curves. Lifetimes of 255?.3fs, 4?.8ps and 3.8?0.1ns were obtained from heterotrimer. It can be seen that the energy transfer speed of homotrimer was faster than that of homotrimer. Thus it could be deduced that the link between the same apoprotein of homotrimer is more compact thanthat between the different apoprotein of heterotrimer, and the former is more propitious to transfer energy fast.8 Influence of temperature on energy transfer kinetics of the pigment molecules in reaction center was studied at low temperature using the femtosecond time-resolved transient and steady state fluorescence spectrophotometer. After analyzed, the fluorescence spectra were compared, and it sh...