The spectral properties and the subunit components of an R-phycoerythrin that was stable at 37°C in phosphate buffer (pH 7.0) with sodium dodecyl sulfate (SDS) were investigated. The R-phycoerythrin was obtained from the phycobilisome that was prepared from the marine red algae <i>Polysiphonia urceolata</i> by step-gradient sucrose centrifugation. By Sephadex G-150 column chromatography and polyacrylamide gel electrophoresis the R-phycoerythrin was prepared from the phycobilisome disassociatin that was incubated at 37¡C for 6 hr in 0.05M phosphate buffer (pH 7.0) containing 5% (w/v) SDS, 2% (w/v) mercaptoethanol and 10% (v/v) glycerol. The absorption spectrum of the R-phycoerythrin in 0.05M phosphate buffer (pH 7.0) showed that it has three absorption peaks at 498 nm, 537 nm and 566 nm, respectively; and therefore, it belongs to three-peak R-phycoerythrin. At room temperature, its fluorescence emission spectrum showed that the emission peak occurs at 578nm. The component analysis by SDS-polyacrylamide gel electrophoresis showed that the R-phycoerythrin is composed of 17.8 KD, 21 KD and 31KD of three colored polypeptides. Linker peptides existed in the R-phycoerythrin may account for its stability in SDS Solution at 37°C. The stable feature, together with its high fluorescence emission efficiency, like most other phycobiliproteins, may let the obtained R-phycoerythrin be a promising agent of fluorescence label for diagnostic uses of various purposes.
This paper reports investigation on time-dependant transmittance of Chl b on nanosecond and picosecond time scale. Temporal anisotropy in Chl b solution were observed by streak camera. The transmitted TEM<sub>00</sub> mode pumped light was distorted by Chl b solution. The distortion may originate from the temporal anisotropy in Chl b solution induced by the high intensity laser pulses. The state of the temporal anisotorpy was contiued and piled up owing to accumulation of the triplet state within the succeeding pulses in the Chl b solution.
This paper reports investigation on third-order nonlinear optical properties of chlorophyll a (Chl a), a kind of natural porphyrin derivative in organisms, by using Z-scan streak- camera system on nanosecond and picosecond time scale. Time- dependant behavior of the third-order optical nonlinearity was examined within duration of a picosecond pulse train along Z direction, and modulation of the transmitted pulses in the pulse train was temporally observed. A slow-accumulated optical nonlinearity was occurred in the diluted Chl a solution besides fast response optical nonlinearity of electronic origin. We propose that the slow-accumulated optical nonlinearity is originated from pileup of triplet states, and that the triplet states accumulation is attributed to enhancement of singlet-triplet orbit coupling brought about by intense optical field of the laser pulse.
Based on a novel concept that intensive optical field may improve alignment of polymer films photopolymerized by linearly polarized laser light, we investigated effects of instantaneous intensity of the laser light and viscosity of the films on alignment of liquid crystals on the photopolymerization-induced anisotropic films. The intensity and the viscosity are the two essential factors related intimately to magnitude and relaxation time of the reorientation Kerr effect. The experiments demonstrated that the increase in the intensity and the decrease of the viscosity improved the photopolymerization-induced orientation of the films. Based on the photochemical points, we discussed causes of the improvement.
AC electroluminescence from organic thin film electroluminescent (OTFEL) devices based on polymer poly(p- phenylene-vinylene) and molecular compound tris(8- hydroxyquinoline) aluminum (Alq<SUB>3</SUB>)was observed. The emission spectra of these devices driven by ac were recorded. The current-voltage (I-V) and brightness-voltage (B-V) were measured. It shows that the performances of OTFEL devices which were driven by ac is as good as those driven by dc. It opens a new application field that organic thin film electroluminescent devices can be driven by both dc and ac.
The luminescence of BaFCl:Eu<SUP>2+</SUP> after ultraviolet under different temperature is studied in this paper. According to the spectra, the temperature effects of two kinds of electron traps is compared and the electron transfer process in read process is discussed.