Behavior of Electrical Properties of Synthetic Chlorophyll Pigment Solution by using the T.E-Model (original) (raw)
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Study of the Photo-Electric Behavior of Spinacea pleracea using the T.E-Model of Chlorophyll Pigment
Objective: To Study the photo-electric behavior of Spinacea pleracea by using the T.E-model of chlorophyll pigment. Methods/Statistical Analysis: The technic and method employed consisted on modeling the chlorophyll as an electrical circuit, to make a statistical analysis of electric conductance process of S. pleracea in light and in darkness by evaluating, the statistical average and statistical autocorrelation function, and make a temporal analysis by evaluating, the temporal average and temporal autocorrelation function. Finding: The electric conductance of Spinacea pleracea leaf plant increases when one passes from darkness to light; the spectral density of power (DSP) of the electric conductance process G(ω,t) under darkness is up to the DSP of the signal when S. pleracea is under light for the whole value of the reduced normalized frequency; the process is non-statistics in the broad sense (SSL) and non ergotic. The resemblance of the flow charge evaluated by autocorrelation functions for different values of the shift parameter is higher in light than in darkness. Application/Improvements: This study provided an additional tool to have an idea about the state of reactional center of photosystem II, knowing that the fluorescence emission testifies the loss of energy during the transfer of excitation to the reactional centers. In the same way, the electric conductance testifies the transfer of electrons released from the special chlorophyll 'a' of the reactional center to the photosynthetic channel.
Insight into incident photon to current conversion efficiency in chlorophylls
Authorea (Authorea), 2020
Photovoltaic properties of the natural dyes of chlorophylls consist of Chl a, Chl b, Chl c2, Chl d, Phe a, Phe y and Mg-Phe a, were studied in the gas phases and water. The extension of the π-conjugated system, the substitution of the central Mg2+ and proper functional groups in the chlorophyll structures can amplify the charge transfer and photovoltaic performance. Chl a shows more favorable dynamics of charge transfer than other studied chlorophylls. Chl d, Phe a, Phe y and Mg-Phe a, have a greater rate of the exciton dissociation in comparison with Chl a, Chl b, and Chl c2 originated from a lower electronic chemical hardness, a lower exciton binding energy, and a bigger electron-hole radius. As a result, better efficiencies of the light-harvesting and energy conversion of the chlorophylls mainly appear in the Soret band. The LHE values of the chlorophylls in water show that solvent favorably affects the ability of light-harvesting of the photosensitizers. Finally, based on the energy conversion efficiency, Chl a, Phe a, and Mg-Phe a, are proposed as the best candidates for using in the dye-sensitized solar cells.
The polyphasic chlorophyll a fluorescence rise measured under high intensity of exciting light
Chlorophyll a fluorescence rise caused by illumination of photosynthetic samples by high intensity of exciting light, the O–J–I–P (O–I1–I2–P) transient, is reviewed here. First, basic information about chlorophyll a fluorescence is given, followed by a description of instrumental setups , nomenclature of the transient, and samples used for the measurements. The review mainly focuses on the explanation of particular steps of the transient based on experimental and theoretical results, published since a last review on chlorophyll a fluorescence induction [Lazár D (1999) Biochimica et Biophysica Acta 1412, 1–28]. In addition to 'old' concepts (e.g. changes in redox states of electron acceptors of photosystem II (PSII), effect of the donor side of PSII, fluorescence quenching by oxidised plastoquinone pool), 'new' approaches (e.g. electric voltage across thylakoid membranes, electron transport through the inactive branch in PSII, recombinations between PSII electron acceptors and donors, electron transport reactions after PSII, light gradient within the sample) are reviewed. The K-step, usually detected after a high-temperature stress, and other steps appearing in the transient (the H and G steps) are also discussed. Finally, some applications of the transient are also mentioned.
Bioelectrochemistry, 2006
A set of expressions is derived which quantifies the chlorophyll fluorescence yield in terms of rate constants of primary light reactions of PSII, the fraction of open and semi-open RCs and of the electric field sensed by the RC in the thylakoid membrane. The decay kinetics of the chlorophyll fluorescence yield after a single turnover excitation in the presence of DCMU show at least two components, one reversible within approx. 1 s and one with a dark reversion lasting more than 30 s. The latter is attributed to photochemical quenching; the fast component is interpreted to be associated at least partially with photo-electrochemical control. It will be illustrated that (i) the sub-maximal fluorescence yield in single turnover excitation is associated with semi-closure of RCs, (ii) the trapping efficiency of semi-closed centers is less than 50% of that of open centers and (iii) the fluorescence yield of antennas with semi-closed RCs has the highest sensitivity to changes in strength of photo-electric fields. D
Excitation kinetics during induction of chlorophyll a fluorescence
Photosynthetica, 2009
We present a chlorophyll fluorometer module system which adapts the intensity to the individual leaf sample by adjusting the quantum flux density of the excitation light so that the fluorescence signal is kept constant. This is achieved by means of a feedback power adjustment of the fluorescence exciting laser diode. Thus, the intensity of the excitation light is adapted to the actual need of a particular sample for quantum conversion without applying exaggeratedly high quantum flux density. We demonstrate the influence of the initial laser power chosen at the onset of irradiation and kept constant during fluorescence rise transient within the first second. Examples are shown for measuring upper and lower leaf sides, a single leaf with different pre-darkening periods, as well as yellow, light green and dark green leaves. The novel excitation kinetics during the induction of chlorophyll fluorescence can be used to study the yield and regulation of photosynthesis and its related non-photochemical processes for an individual leaf. It allows not only to sense the present state of pre-darkening or pre-irradiation but also the light environment the leaf has experienced during its growth and development. Thus, the individual physiological capacity and plasticity of each leaf sample can be sensed being of high importance for basic and applied ecophysiological research which makes this new methodology both innovative and informative.
Stochastic Electrical Behavior of Splina Liquid Chlorophyll Drink
Objective: Our purpose is to study the stochastic electrical behavior of Splina liquid chlorophyll by using the T. E.-model and to compare it with the natural one. Methods/Statistical Analysis: The technic and method employed consisted of modeling the chlorophyll as an electrical circuit, to make a statistical analysis of the extra chlorophyll space resistance process of Splina solution in light and in darkness by evaluating, the statistical average and statistical autocorrelation function, and make a temporal analysis by evaluating, the temporal average and temporal autocorrelation function. Findings: It comes out from our study that, for a suitable lighting angle, and repartition of Splina solution component, after adding of purified water, RO-EDI (Reverse Osomosis-Electrode Ionization) water and sodium copper chlorophyll in to the natural chlorophyll, the electric behavior of Splina chlorophyll solution is like the natural one. For the three different disposition of liquid chlorophyll glass, the Spectral Density of Power (DSP) of the extra-chlorophyll space resistance process R(ω,t) when the splina solution is under light is up to the DSP of the signal when the splina solution is under darkness for the whole value of the reduced normalized frequency; the process is non-statistics in the broad sense (SSL) and non ergotic. The resemblance of the flow charge with him for different value of the shift parameter is high in light than in darkness. Application/Improvements: This study provided an additional tool to verify if after the addition of new substances, that the photoelectric, statistical and temporal behavior of the resulting product is identical to that of the initial natural one.
Biochimica et Biophysica Acta (BBA) - Bioenergetics, 1978
Absorption and fluorescence spectra in the red region of water-soluble chlorophyll proteins, Lepidium CP661, CP663 and Brassica CP673, pigment System II particles of spinach': chloroplasts and chlorophyll a in diethylether solution at 25°C were analyzed by the curve-fitting method (French, C.S., Brown, J.S. and Lawrence, M.C, (1972) Plant Physiol. 49, 421--429). It was found that each of the chlorophyll forms of the chlorophyll proteins and the pigment System II particles had a corresponding fluorescence band with the Stokes shift ranging from 0.6 to 4.0 nm.