The absorption coefficients of chloroplast of leaf mustard were measured by a spectrophotometer. The leaves were
collected from seven treatments with different lighting. The chlorophyll content was calculated following Arnon
equation. LEDs for filling the light source can increase the conduction of plants. Compared with other treatments,
Chlorophyll in the leaves got an higher concentration under the lamping of red LEDS to blue LEDS for 7:1 .
The ultrafast emission of nanodiamond powder has been detected with ultrafast fluorescence spectroscopy. The ultrafast emission spectrum has been deconvoluted by the Monte-Carlo method and the results show 2 fast decays as 60ps and 350ps, with weighting about 80 percent and 20 percent of the whole emission intensity respectively. Such fast emission has not been detected under the same experimental condition for the samples of pure and defected bulk diamonds. The reason for such ultrafast process has been discussed.
In this letter, self-aligned dual implantation technique was successfully used to speed up the carrier transportation from sidewall quantum well (SQWL) to quantum wire (QWR) region in V-groove AlGaAs/GaAs QWR structure. Photoluminescence (PL) and time resolved photoluminescence (TRPL) show that the lateral confinement was enhanced after intermixing by intermixing the necking region. Lifetime was obviously enlonged after selective intermixing, which comes from the enhanced lateral carrier confinement. Strong hot exciton relaxation process in QWRs region is observed after selective intermixing.
Theoretical descriptions of excitation energy transfer between chromophores in allophycocyanin are presented, including bilateral energy transfer paths between chromophores, and are expressed, based on Foster interaction mechanism, as Pauli master equations. Group analysis in C<SUB>3</SUB> symmetry is performed to carry out analytic expressions for fluorescence decays which is generally of triexponential with effects of chromophore coupling and exciton splitting taken account. It is pointed out that the time constant of each decay component contains mixed information of different energy transfer paths, and therefore show its dependence on subtle configuration of chromophores, probably related to site heterogeneity and thus to inhomogeneous broadening previously observed.
Both theoretical and experimental studies are presented on chromophore excited-state coupling in linker-free allophycocyanin (APC), one of the antenna phycobiliproteins in algal photosynthesis. A three-site-coupling model has been introduced to describe the exciton interaction mechanism amoung the excited (beta) chromophore in APC, and the exciton energy splitting is estimated. Picosecond polarized fluorescence experiments both on monomeric and trimeric APC isolated from alga Spirulina platensis have been performed. The experimental results show that APC monomer and trimer exhibit remarkedly different spectropic characteristics, and satisfy the suggestion of strong excited- state coupling among chromophores in APC.
Single ps pulse spectroscopic techniques have been employed to investigate excited-state dynamics of R-phycoerythrin (R-PE) isolated from two red algae Polysiphonia urceolata and Porphyra yezoensis, respectively, at various excitation photon densities in a range of 8 X 10<SUP>14</SUP> $AP 1 X 10<SUP>17</SUP> photons/cm<SUP>2</SUP>. The fluorescence quantum yields of the R-PE from the two algae are found to decrease in logarithm with increasing of excitation intensity due to S<SUB>1</SUB>-S<SUB>1</SUB> exciton collision. A fast component in addition to a slow one recorded at low excitation density and a large initial anisotropy are observed at higher excitation density. Different dynamical characteristics of exciton collision between the cases of Polysiphonia urceolata and Porphyra yezoensis are shown and proposed to be owing to different numbers of excited pigments available and chromophore architectrue in R-PE from different biological sources.