Molecular Movements and Dynamics in Solutions Studied by Fluorescence Depolarization Measurement

1993 ◽  
Vol 58 (2) ◽  
pp. 213-233 ◽  
Author(s):  
Zuzana Limpouchová ◽  
Karel Procházka ◽  
Vlastimil Fidler ◽  
Jiří Dvořák ◽  
Bohumil Bednář
Keyword(s):  
Energy Transfer ◽  
Rotational Diffusion ◽  
Experimental Studies ◽  
Theoretical Models ◽  
Reorientational Motion ◽  
Fluorescence Depolarization ◽  
Time Resolved ◽  
Langevin Model ◽  
Theoretical Predictions ◽  
Media Systems

Theories allowing interpretation of the results of time-resolved polarization spectrofluorimetry in solutions are reviewed and their applicability under various conditions is discussed. For the reorientation of rigid molecules in an isotropic medium, the most frequently employed models are presented, such as rotational diffusion model, the Fokker-Planck-Langevin model, etc. Systems with internal rotation, systems in anisotropic media, systems with a complex electron relaxation and systems with energy transfer are discussed as examples of more complex systems. A special attention is devoted to the polarization fluorimetry of probes bound to/or sorbed at polymer and biopolymer chains. The review focuses on theoretical models of reorientational motion for interpretation of fluorescence anisotropy decays. Experimental studies and computer simulations are discussed only when it is necessary for comparison with theoretical predictions. Complicated models for simultaneous reorientational motion and energy transfer, solvent relaxation, etc., although very important for many applications, exceed the scope of this review and are mentioned only very briefly.

Chromophore Dynamics in Sol-Gel Glasses and Xerogel Clad Fiber Optic Sensors

1994 ◽  
Vol 346 ◽  
Author(s):  
Drew L'Esperance ◽  
Clarice A. Browne ◽  
Eric L. Chronister
Keyword(s):  
Energy Transfer ◽  
Fiber Optic ◽  
Rotational Diffusion ◽  
Sol Gel ◽  
Fiber Optic Sensors ◽  
Fiber Optic Sensor ◽  
Time Resolved ◽  
Optic Sensor ◽  
Sensor Device ◽  
Gel Glasses

ABSTRACTTime-resolved depolarization measurements are used to investigate rotational diffusion and optical energy transfer dynamics of chromophores incorporated into silica and aluminosilica solutions, gels, and glasses. The use of an organically doped sol-gel clad waveguide as a novel intrinsic fiber optic sensor device is also demonstrated, and advantages of time-resolved detection of the fiber optic sensor are illustrated.

Analysis of rotational diffusion of coumarin laser dyes

2015 ◽  
Vol 93 (1) ◽  
pp. 3-6 ◽  
Author(s):  
Y.F. Nadaf ◽  
C.G. Renuka
Keyword(s):  
Rotational Diffusion ◽  
Relaxation Times ◽  
Laser Dyes ◽  
Fluorescence Depolarization ◽  
Time Resolved ◽  
Diffusion Analysis ◽  
Alkane Solvents ◽  
Alcohol Solvents ◽  
Coumarin Laser Dyes ◽  
Coumarin 6

Rotational diffusion analysis of two laser dyes, coumarin 6 and coumarin 30, has been studied in alkane and alcohol solvents using steady-state and time-resolved fluorescence depolarization methods. The rotational diffusion times of these probes vary linearly as a function of viscosity over the range of temperature studied. It is observed that the rotational diffusion time measurements of molecules in alcohol and alkane have relaxation times typically on the order of picoseconds, though they are greater in alcohol than in alkane solvents. However, it was observed that coumarins rotate faster in n-hexane and n-heptane than in n-propanol and n-butanol solvents, and the observed results are discussed in the last section.

scholarly journals Time-Resolved Polarized Fluorescence of C-Phycocyanin and Its Subunits from Mastigocladus laminosus

1984 ◽  
Vol 39 (6) ◽  
pp. 606-616 ◽  
Author(s):  
P. Hefferle ◽  
P. Geiselhart ◽  
T. Mindl ◽  
S. Schneider ◽  
W. John ◽  
...  
Keyword(s):  
Energy Transfer ◽  
Protein Conformation ◽  
Streak Camera ◽  
Fluorescence Decay ◽  
Polarized Fluorescence ◽  
Fluorescence Depolarization ◽  
Time Resolved ◽  
Α Subunit ◽  
Induced Changes ◽  
Kinetics Of

The influence of aggregation and temperature on the excited state kinetics of C-phycocyanin from Mastiqocladus laminosus has been studied. Polarized fluorescence decay curves have been recorded using a synchronously pumped dye laser in conjunction with a synchroscan streak camera. The experimental data for all samples can be fit satisfactorily assuming a biexponential decay law. Fluorescence depolarization times have been interpreted in terms of energy transfer among the different chromophores. The influence of temperature is only moderate on the intra­molecular relaxation, but pronounced on the rates of energy transfer. Both are dependent on the size of the aggregate. The biexponential decay of the α-subunit containing only one chromophore, indicates the presence of different subsets of chromophores in these samples. The results are discussed in terms of variations of the chromophore arrangements upon temperature induced changes in the protein conformation.

Optical Energy Transfer and Photochromism in Doped Sol-Gel Glasses

1992 ◽  
Vol 276 ◽  
Author(s):  
Drew L'Espérance ◽  
John M. Pelo ◽  
Eric L. Chronister
Keyword(s):  
Energy Transfer ◽  
Sol Gel ◽  
Optical Power ◽  
Time Resolved Fluorescence ◽  
Fluorescence Depolarization ◽  
Time Resolved ◽  
Optical Energy ◽  
Aluminum Phthalocyanine ◽  
Aluminosilicate Glasses ◽  
Gel Glasses

ABSTRACTOrganically doped sol-gel glasses are investigated by optical absorption and time-resolved fluorescence depolarization measurements. Silicate and aluminosilicate glasses have been doped with quinizarin (Q) and aluminum phthalocyanine chloride (CAP). The structure and bonding in these inorganic sol-gel solids is different from that in frozen liquids and organic polymers, and the unique dynamics of these systems are a motivation for this study. Both rotational dynamics and optical energy transfer of doped chromophores in sol-gel glasses are investigated by time-resolved fluorescence depolarization measurements. Since the dipole-dipole energy transfer rate is very sensitive to transfer distance, these measurements are used to probe the spatial distribution of dopant molecules within these solids. We also present photochromic results on aluminum phthalocyanine chloride doped silicate sol-gel glasses and discuss possible uses as an optical power limiting material.

A Relativistic Newtonian Mechanics Predicts with Precision the Results of Recent Neutrino-Velocity Experiments

2014 ◽  
Vol 6 (1) ◽  
pp. 1032-1035 ◽  
Author(s):  
Ramzi Suleiman
Keyword(s):  
Null Hypothesis ◽  
Experimental Studies ◽  
Theoretical Models ◽  
Newtonian Mechanics ◽  
Speed Of Light ◽  
Symmetry Principle ◽  
Proposed Model ◽  
Significant Difference ◽  
The One ◽  
Complete Collapse

The research on quasi-luminal neutrinos has sparked several experimental studies for testing the "speed of light limit" hypothesis. Until today, the overall evidence favors the "null" hypothesis, stating that there is no significant difference between the observed velocities of light and neutrinos. Despite numerous theoretical models proposed to explain the neutrinos behavior, no attempt has been undertaken to predict the experimentally produced results. This paper presents a simple novel extension of Newton's mechanics to the domain of relativistic velocities. For a typical neutrino-velocity experiment, the proposed model is utilized to derive a general expression for . Comparison of the model's prediction with results of six neutrino-velocity experiments, conducted by five collaborations, reveals that the model predicts all the reported results with striking accuracy. Because in the proposed model, the direction of the neutrino flight matters, the model's impressive success in accounting for all the tested data, indicates a complete collapse of the Lorentz symmetry principle in situation involving quasi-luminal particles, moving in two opposite directions. This conclusion is support by previous findings, showing that an identical Sagnac effect to the one documented for radial motion, occurs also in linear motion.

Sign in / Sign up

Export Citation Format

Share Document