Polarization Characteristics Of Fluorescence Research Articles

Super-resolution reconstruction for subsurface defects of optical elements based on CdSe/ZnS quantum dots fluorescence dichroism

The subsurface defects (SSD) of optical elements have a significant impact on the service life and laser damage threshold of the inertial confinement nuclear fusion optical system. Due to the optical diffraction limit, fluorescence microscopy has limited image resolution for detecting SSD in optical elements, making it challenging to meet the requirements for precision detection. A super-resolution method is proposed in this paper for detecting SSD in optical elements based on the fluorescence polarization characteristics of CdSe/ZnS quantum dots fluorescence dichroism. By enhancing the imaging sparsity of adjacent fluorophores through a polarization modulated excitation laser and utilizing the fluorescence polarization modulation algorithm, the resolution is achieved beyond the optical diffraction limit. The results demonstrate that the proposed method in this paper can obtain super-resolution images of SSD in optical elements with at least a two-fold increase in lateral resolution. This approach effectively improves detection accuracy for SSD and holds significant guiding significance. In addition, it also has application value for assessing the quality of high-precision optical elements.

Blood fluorescence polarization characteristics of saturated fatty acid biological effects

The fluorescence spectra of normal and lard diet intake whole blood solution induced by a laser with an excitation wavelength of 407nm, and the polarization fluorescence spectra at angles of 0°, 35°, 55° and 90° were studied experimentally. The polarization state was tested by fluorescence intensity Stokes vector parameters. Through Mueller matrix calculations, we discuss the polarization degrees of whole blood solution during different time, the effects on fluorescence parameters of whole blood solution after lard diet intake. The results show that both the main fluorescence peaks of normal and lard diet intake whole blood solution locate at about 612nm. The polarization degree of the whole blood solution after lard diet intake fluctuates greatly and is evidently higher than that of normal one. It is analyzed that growing blood cells in size and increasing blood viscosity make the molecular rotation of lard diet intake hindered.

Effect of solvation on polarization characteristics of fluorescence for 1,3,4-oxadiazole derivatives in binary solvents

We have studied the degree of fluorescence polarization for 1,3,4-oxadiazole derivatives in the binary solvents hexane-ethanol, toluene-ethanol, toluene-acetonitrile, 2-propanol-water, dioxane-water, 2-propanol-glycerol, glycerol-water vs. the composition of the solvent. We have shown that in systems with predominant universal interactions, the characteristic changes in the degree of polarization reflect the change in the viscosity of the mixture, while in systems with pronounced specific interactions they reflect the characteristic structural features of the fluorescent centers.

Spectral, kinetic and polarization characteristics of luminescence of acriflavine in polymeric matrix under pulsed excitation with different durations and intensities

Spectral, kinetic and polarization characteristics of fluorescence and thermally activated delayed fluorescence (TADF) of dye solid solutions have been investigated. It was shown that the increasing of the excitation pulse duration results in rise of TADF decay time, but an increasing of the long pulse excitation intensity results in a faster TADF decay. In the presence of Förster resonance energy transfer (FRET) the fluorescence spectrum is shifting non-monotonically with time when the intensity of the excitation pulse is high. At the time moment when the excitation is switched off the polarization degree of luminescence of the concentrated dye solutions strongly reduces. The energy transfer from the molecules in the S 1 state to the molecules in the T 1 state reduces the depolarization of luminescence caused by FRET. Numerical simulations were made by means of Monte-Carlo integrations and results were compared with experimental data obtained for acriflavine in polyvinyl alcohol films.

Correlations of Structure and Rates of Energy Transfer for Through-Bond Energy-Transfer Cassettes

Fluorescent DNA-labeling cassettes are designed to have a common absorbing chromophore matched to a single exciting laser wavelength, but up to four different emitters. Experiments reported here have examined the energy-transfer rates and fluorescence polarization characteristics for two different types of cassette, involving three distinct relative orientations of the donor and acceptor transition moments and the axis of the rigid linker. Energy-transfer times range from <200 fs to approximately 20 ps, the fastest transfer times occurring when the transition moments of the donor and acceptor species are aligned parallel to the linker axis. Experimental evidence is presented that supports a through-bond energy-transfer mechanism, in contrast with a commercial DNA-labeling agent, which exhibits much slower transfer times controlled by FRET. These rigid cassettes also exhibit polarized fluorescence from the acceptor species, so that this particular type of DNA-labeling probe has some of the advantages of single-molecule probes such as rhodamine and coumarin dyes.

Spectral-Luminescent Properties of Substituted Tetraazachlorin and of Its Zinc Complex

The spectral, energy, kinetic, and polarization characteristics of fluorescence of di(tert-butylbenzo)barrelene-substituted tetraazachlorin and of its zinc complex in solutions are measured. The results are compared with similar data for tetraazaporphin and unsubstituted chlorin. Quenching of the fluorescence of the tetraazachlorins under investigation is noted.

Luminescence Studies in Ca(PO3)2:Eu3+Glass by Laser-Induced Fluorescence Line-Narrowing Technique. I. Optical Transition Mechanism of the5D0-7F0Line

Fluorescence spectra have been measured in Ca(PO 3 ) 2 :Eu 3+ at 77 K under dye laser excitation at various energies within the absorption lines due to the transitions 7 F 0 , 7 F 1 - 5 D 0 , 5 D 1 . It has been found that the 5 D 0 - 7 F 0 transition probability and the mean energy of the three 5 D 0 - 7 F 1 lines are linearly correlated with the energy of the 5 D 0 - 7 F 0 line, and also that this energy is quadratically correlated with the transition energy between 5 D 0 and the lowest level of 7 F 1 . These results are interpreted in terms that the spreads of these energies and the transition probability are due to the site-to-site variation in the second-order crystal-field parameter. Further, the forbidden 5 D 0 - 7 F 0 transition is concluded to be allowed by the borrowing of the intensity from the 5 D 0 - 7 F 2 ( M J =0) line through the J -mixing. Using polarization characteristics of fluorescence, whether the lines are due to the electric or magnetic dipole transition is determined and the Stark...

Fluorescence polarization and intramolecular dynamics in S1 of pyrazine, pyrimidine, and s-triazine vapors

The excitation polarization (EP) spectra of fluorescence of pyrazine, pyrimidine, and s-triazine in the vapor phase have been obtained at room temperature along the rotational contour of the absorption bands belonging to the S0→S1 transition. The decay curves of the parallel and perpendicularly polarized fluorescence of these molecules have also been observed. At low pressures, the degree of polarization of both fast and slowly decaying components of fluorescence emitted from the initially prepared vibronic level (IPL) exhibits a remarkable variation along the rotational contour in every case, whereas the broad fluorescence of pyrimidine and s-triazine emitted from the levels to which nonradiative transition occurs from the IPL is not polarized with excitation to any rotational level. The EP spectra of the IPL fluorescence are well reproduced theoretically by considering the resonance fluorescence from fully resolved rotational levels in S1 and by employing a symmetric top approximation. The EP spectra of the broad fluorescence are also reproduced fairly well by assuming that K scrambling occurs within the singlet manifold following the intramolecular vibrational redistribution from the IPL and that the broad fluorescence is emitted from such K scrambled levels. On the basis of these results, polarization characteristics of fluorescence and the role of molecular rotation in the intramolecular dynamics of these molecules are discussed.

Research in the field of 2,4,5-triarylimidazoles. Communication 3. Spectral-luminescence properties of 1,4-BIS(4,5-diphenyl-1H-imidazol-2-yl)benzene

1. The polarization characteristics of fluorescence and phosphorescence have been measured for 1,4-bis(4,5-diphenyl-1H-imidazol-2-yl)benzene in 1-propanol at 77°K. 2. The S0 → S1 transition is due to oscillation of charge in the π-conjugated system of the molecule along its long axis; the S0 → S2 transition is localized in the imidazole fragments.

Analysis of the spatial organization of anisotropic structures on the basis of fluorescence polarization characteristics

Analysis of the spatial organization of anisotropic structures on the basis of fluorescence polarization characteristics

Fluorescence polarization characteristics of the complexes between ethidium bromide and rRNA, tRNA, and DNA

Fluorescence polarization studies show that the rotational relaxation times for ethidium bromide intercalated in tRNA, rRNA, or DNA increase in that order and are quite different. Polarization is strongly affected by salt concentration and by association of nucleic acid with protein. Evidence for a change in rotational characteristics above the transition temperature of 32 ° is presented. Fluorescence properties of use in intracellular investigations with ethidium bromide are described.

Fluorescence methods in polymer science

AbstractVarious aspects of the application of fluorescence characteristics in the field of polymer research are described. The polarization characteristics of fluorescence, that is, the angular distribution of the intensity of the polarized component, are indicative of the distribution patterns of fluorescent molecules in the medium. This principle can be utilized for the investigation of molecular orientation behavior in polymer solids. Examples are given for the molecular orientation behaviors during the deformation of poly(vinyl alcohol) and polypropylene films. The phenomenon of rotational depolarization of fluorescence is applied to the measurement of micro‐Brownian motions of polymer chains and the local viscosity of polymer solutions and melts. The internal structure of concentrated poly(styrene) solutions and the molecular motions in the melts of n‐paraffins and polyethylene homologs are discussed. Rotational relaxation time ranging from 10−12 to 10−5 sec can be measured by this method by using the lifetime of excitation of fluorescent groups as the reference time scale. The phenomenon of the excimer fluorescence emitted from the excited dimer provides a new method for studying molecular configuration and conformation of polymer molecules. Examples are given for the case of naphthalenecontaining polymers. The sequence of monomeric units in copolymers of vinylnaphthalene and styrene are studied from the intensity of excimer fluorescence relative to that of ordinary fluorescence from the naphthalene groups. The intramolecular excimer formations of polymer molecules are also discussed in relation to molecular motions.

Fluorescence methods in polymer science

Various aspects of the application of fluorescence characteristics in the field of polymer research are described. The polarization characteristics of fluorescence, that is, the angular distribution of the intensity of the polarized component, are indicative of the distribution patterns of fluorescent molecules in the medium. This principle can be utilized for the investigation of molecular orientation behavior in polymer solids. Examples are given for the molecular orientation behaviors during the deformation of poly(vinyl alcohol) and polypropylene films. The phenomenon of rotational depolarization of fluorescence is applied to the measurement of micro-Brownian motions of polymer chains and the local viscosity of polymer solutions and melts. The internal structure of concentrated poly(styrene) solutions and the molecular motions in the melts of n-paraffins and polyethylene homologs are discussed. Rotational relaxation time ranging from 10−12 to 10−5 sec can be measured by this method by using the lifetime of excitation of fluorescent groups as the reference time scale. The phenomenon of the excimer fluorescence emitted from the excited dimer provides a new method for studying molecular configuration and conformation of polymer molecules. Examples are given for the case of naphthalenecontaining polymers. The sequence of monomeric units in copolymers of vinylnaphthalene and styrene are studied from the intensity of excimer fluorescence relative to that of ordinary fluorescence from the naphthalene groups. The intramolecular excimer formations of polymer molecules are also discussed in relation to molecular motions.