Papers by Keyword: Fluorescence Intensity

Abstract: CaWO₄: xNd³⁺ (x = 0.005, 0.008, 0.01, 0.015, 0.02, 0.025 0.03) powders have been synthesized by high-temperature solid state reaction. The results of the XRD indicate that Nd³⁺ ions have entered into the crystal lattice in all compounds successfully. The reflectance spectra show that the matrix has strong absorption. The emission spectra, excitation spectra and different lifetimes between CaWO₄ and CaWO₄: 0.5% Nd³⁺ indicate that efficient energy transfer occurs from WO₄^2- cluster to Nd³⁺ ions. On the basis of the above work, the dependence of fluorescent spectra on temperature was studied. It turned out that, not only the excitation spectra appeared red shift with increasing temperature, but also the dependence of the near infrared fluorescent intensity on temperature is fitting with a linear function. It might be served as a promising phosphor for temperature sensor device.

Abstract: A fluorescent markers based two-dimensional parallel detection technique of Micro-fluidic chip is studied. In a special designed fluid field of test sample, excite fluorescence of micro-spheres probe by pulse-laser and employ high sensitivity CCD to catch it. The entire information from micro-fluidic chip can be obtained via a computer post-processing of the caught signal of fluorescence. Analyzed the probe flow state and fluorescence signal intensity of detection program. Established the expressions of fluorescence signal intensity and the parameters of detection system. Validation experiments indicate that this detection method has the advantages of rapid, accurate and high sensitivity.

Abstract: The fluorescence intensity of double-stranded DNA (ds-DNA) hybridized by fluorescent 2-aminopurine (2-AP) oligonucleotide probe and different mismatched bases was studied by fluorescence spectra in this paper. The experiment designed and synthesised four oligonucleotide sequences with the bases of adenine (A), cytosine (C), guanine (G), thymine (T), and determined the fluorescence intensity of the mismatched double-stranded DNA. The results implied that the fluorescence intensity of oligonucleotide probe was varied due to different mismatched bases. And the fluorescence intensity was 546.9 with the ratio of 3.13, which showed a significantly increase as the mismatched base was A. While the mismatched base was T, the fluorescence intensity quenched to 43.26, as the ratio was 0.25. For C and G, the fluorescence intensity of 2-AP was 99.14 and 89.03, respectively, which showed a different degree of reduction.

Abstract: A novel unsymmetrical photochromic diarylethene 1-(2, 5-dimethyl-3-thienyl)-2-[2-methyl-5-(2,2-dibutylfluorene)-3-thienyperfluorocyclo-pentene (1o) was synthesized and its photochromic and fluorescent properties were investigated. Diarylethene 1 changed the color from colorless to hyacinthine upon irradiation with 297 nm UV light, in which absorption maxima were observed at 554 nm in hexane and at 565 nm in PMMA amorphous film, respectively. This new photochromic system also exhibited remarkable fluorescence intensity both in solution and in PMMA film. The fluorescence spectra showed a systematic red-shift with the emission intensity of diarylethene 1 in a photo-stationary state was quenched to ca. 64%. The cyclization and cycloreversion quantum yields of 1 in hexane were determined to be 0.56 and 0.002. Polarization multiplexed image recording can be carried out in this diarylethene 1c/PMMA film as recording medium film.

Abstract: When an X-ray photon which is generated by the sample enters into the detector, pulses can be produced and recorded. The detector is unable to respond to another photon that enters at the same time when a photon is being detected. The time that the detector takes to respond to a photon is regarded as dead time. For the x-ray fluorescence detector, the recorded count is less than the real count impulse due to dead time. Hence, to correct x-ray intensity of samples whose element content is vastly different, determination of dead time is necessary. In this paper, a new and complete way to determine dead time is proposed, which can be summarized as “intensity pair method”. Three “intensity pairs” were used for determining dead time, which were “intensity pair” of collimators (S2 and S4), “intensity pair” of spectral lines (Kα and Kβ) and “intensity pair” of beads with different flux-sample ratio (higher SH and lower SL analyte content in the beads). It comes to a conclusion that dead time obtained from “intensity pair” of beads is the most practical method for correcting X-ray fluorescence intensity. As for routine analysis, the dead time of proportional counter can be accurate to 1×10-9s, which can make intensity correction error less than 0.1%.

Abstract: Two kinds of dendritic 8-hydroxyquinoline ligands were efficiently prepared by convergent method, and characterized by IR, 1H NMR, 13C NMR and MS. The fluorescent properties of dendritic ligands and their Zn(II) complexs were studied. The results indicate that this new methold is readily, which generates virtually no by-products. All dendritic 8-hydroxyquinoline derivatives have good solubility in most of organic solution. These dendritic derivatives show good fluorescence, which can be anticipated as a type of important functioned materials for OLEDs.

Abstract: This study explores a series of optical, thermal, and structural properties based on zinc-aluminum phosphate glasses that doped with varied rare earth (RE) elements Yb2O3 and P2O5 components replaced by SiO2. It was found that for 60P glasses system, 7 mol% Yb2O3 doped has the maximum fluorescence but quenching when Yb2O3 is doped up to 9 mol%. In addition, with increasing the content of Yb2O3 the absorption intensity increased. According to Raman spectra, we found the Yb3+ and Si4+ ions for the impact of network structure of glass, SiO2 added to make the network structure of phosphate glasses at 450-500cm-1 and 600-650cm-1 were formed O-T-O bond and T-O-T bond(T=Si, Al).

Abstract: This paper discusses the structure design, light conversion agents, vehicles, colorants and the selection of other functional additives of light conversion advanced invisible falsification- resistant ink, the preparation of the light conversion falsification-resistant ink and rare earth metal europium complex, and analyzes rare earth metal europium complex, Eu(C5H7O2)3C12H8N2, through infrared spectrometer, element analyzer and fluorescence spectrometer. The results of the above analysis identify the composition of rare earth metal europium complex, its excitation spectrum ranging from 200nm to 400nm, and its emission spectrum ranging from 580nm to 640nm. Experiments suggest when the mixture of rare earth metal europium complex and white ink with titanium dioxide in a fixed proportion is printed on any objects, it appears reddish orange light under ultraviolet irradiation, which achieves the advanced invisible anti-counterfeiting effect.

Abstract: A new effective imaging detecting system has been used to determinate of intracellular calcium. The fluorescence Image acquisition and analysis was realized with fluorescence imaging detecting system. A designed microfluidic chip has been built. Cell fostering, staining and other operations can be implemented on it. Based on it, a new detecting means was developed for fluorometric measurement. The concentration of intracellular calcium ion can been calculated by using the fluorescence ratio method. A series of experiments were performed by using the detecting system. The experimental results show the ratio of fluorescence intensity was positively correlated to the raising temperature and enhancing shear stress.

Abstract: According to the Lambert-Beer laws, the fluorescence spectra of oil in water were investigated by measuring excitation-emission matrixes with FS920 fluorescence spectrometer. On the basis of the three-dimensional fluorescence spectra of oil in water, the excitation wavelength of 290nm and emission wavelength of 324nm were chosen for the quantitative analysis of oil in water. The results show that the concentration of oil in water is linearly proportional to the fluorescence intensity in the range of 1ppm-100ppm, and the measurement model of concentration is obtained with the linear correlation coefficient of 0.9993. The artificial samples has also been tested and the results are satisfactory. The recovery is in the range of 92%-106%. The research provides experimental basis for the quantitative analysis of multi-component oil in water.