Energy transfer and dynamical structure

1976 ◽  
Vol 9 (1) ◽  
pp. 21-33 ◽  
Author(s):  
Josef Eisinger
Keyword(s):  
Energy Transfer ◽  
Relaxation Times ◽  
Experimental Methods ◽  
Rotational Relaxation ◽  
Biological Macromolecules ◽  
Dynamical Structure ◽  
Analytical Instrument ◽  
Fluorescence Depolarization ◽  
X Ray ◽  
Molecular Weights

It is only some 50 years ago that biophysicists obtained reliable experimental methods for estimating the molecular weights of biological macromolecules, chiefly as a result of Svedberg's work in developing the ultracentrifuge as an analytical instrument (Svedberg & Pedersen, 1940). Having gained some understanding of the size of proteins, interest soon thereafter turned to the shape and rotational relaxation times of these molecules, and Perrin's work on fluorescence depolarization helped to lay the foundations there (Perrin, 1929). Biophysics had to wait for the development of X-ray spectroscopy of proteins and nucleic acids to provide a picture of the interior structure of biological macromolecules.

Investigation of Rotational Relaxation by Double Resonance and Stark Switch Techniques

1980 ◽  
Vol 35 (8) ◽  
pp. 832-840
Author(s):  
W. Schrepp ◽  
H. Dreizler ◽  
A. Guarnieri
Keyword(s):  
Double Resonance ◽  
Relaxation Times ◽  
Experimental Methods ◽  
Rotational Relaxation ◽  
Triple Resonance ◽  
Static Electric Field ◽  
First Order ◽  
Four Levels ◽  
Relative Change

Abstract For the four rotational levels JK₋K₊ = 101, 110,212 and 221 of ethylene oxide all possible four level double resonance experiments for dipole allowed transitions have been performed to investigate collisional effects and to determine the relative change of signal intensity, η = ⊿I/I, due to high power pump radiation. The T1 and T2-relaxation times have been measured for all dipole allowed transitions within these four levels. A combination of the data obtained from both experimental methods allows the determination of rate and bath constants taking into account only first order dipolar transitions. No further restrictions have been used. This approximation is supported by a triple resonance experiment. In addition to the pure gas investigation in the absence of external fields, rotational relaxation has been studied in the presence of a static electric field and in a mixture with hydrogen.

Three-dimensional crystallization of membrane proteins

1988 ◽  
Vol 21 (4) ◽  
pp. 429-477 ◽  
Author(s):  
W. Kühlbrandt
Keyword(s):  
High Resolution ◽  
Membrane Proteins ◽  
Membrane Protein ◽  
Protein Complexes ◽  
Three Dimensional ◽  
Biological Macromolecules ◽  
X Ray ◽  
X Ray Crystallography ◽  
Membrane Protein Complexes ◽  
Essential Prerequisite

As recently as 10 years ago, the prospect of solving the structure of any membrane protein by X-ray crystallography seemed remote. Since then, the threedimensional (3-D) structures of two membrane protein complexes, the bacterial photosynthetic reaction centres of Rhodopseudomonas viridis (Deisenhofer et al. 1984, 1985) and of Rhodobacter sphaeroides (Allen et al. 1986, 1987 a, 6; Chang et al. 1986) have been determined at high resolution. This astonishing progress would not have been possible without the pioneering work of Michel and Garavito who first succeeded in growing 3-D crystals of the membrane proteins bacteriorhodopsin (Michel & Oesterhelt, 1980) and matrix porin (Garavito & Rosenbusch, 1980). X-ray crystallography is still the only routine method for determining the 3-D structures of biological macromolecules at high resolution and well-ordered 3-D crystals of sufficient size are the essential prerequisite.

Color tunable Ca8ZnM(PO4)7 (M = Lu/Tb, Lu/Eu, Tb/Eu) phosphors: luminescence, energy transfer and thermal stability studies for n-UV white LEDs

2021 ◽  
Author(s):  
Jing Yan ◽  
Chunyan Jiang ◽  
Yulun Xian ◽  
Jianbang Zhou ◽  
Hong Li ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Energy Transfer ◽  
High Temperature ◽  
Solid State ◽  
Powder Diffraction ◽  
Stability Studies ◽  
X Ray ◽  
White Leds ◽  
Color Tunable ◽  
Xrd Patterns

A series of Tb3+- and Eu3+-doped Ca8ZnLu(PO4)7 (CZLP:Tb3+ and CZLP:Eu3+) as well as Ca8ZnTb(PO4)7:Eu3+ (CZTP:Eu3+) phosphors have been prepared via the traditional high-temperature solid-state reaction. X-ray powder diffraction (XRD) patterns...

Comparative Spectroscopic Studies on Luminescence Performance of Er3+ Doped Tellurite Glass Embedded with Different Nanoparticles (Ag Co and Fe) at 0.55 μm Emission

2021 ◽  
Vol 317 ◽  
pp. 81-86
Author(s):  
Syariffah Nurathirah Syed Yaacob ◽  
Md. Rahim Sahar ◽  
Faizani Mohd Noor ◽  
Nur Liyana Amiar Rodin ◽  
Siti Khadijah Mohd Zain ◽  
...  
Keyword(s):  
Energy Transfer ◽  
Ground State ◽  
Tellurite Glass ◽  
Spectroscopic Studies ◽  
The Other ◽  
X Ray Diffraction ◽  
Melt Quenching ◽  
X Ray ◽  
Doped Glass ◽  
Luminescence Performance

The spectroscopic performance of Er3+ doped glass at 0.55 mm emission contain different nanoparticles NPs have been comparatively evaluated. Glass containing 1.0 mol % of Er3+ doped with different NPs (Ag, Co and Fe ) have been prepared using melt quenching technique. X-ray diffraction analysis reveals the all the prepared samples are amorphous. The UV-Vis absorption spectra of all glasses show several prominent peaks at 525 nm, 660 nm, 801nm, 982 nm and 959 nm due to transition from ground state 4I15/2 to different excited of 2H11/2, 4F9/2, 4I9/2, 4I11/2, and 4I13/2. The emission of Er3+ at 0.55 mm for glass contain Ag NP shows significant enhancement about 3 folds up to 0.6 mol%. On the other hand, the emission of Er3+ at 0.55 mm for glass containing Fe NPs and Co NPs intensely quench probably due to the energy-transfer from Er3+ ion to NPs and magnetic contributions.

scholarly journals The calculation of TV, VT, VV, VV' − rate coefficients for the collisions of the main atmospheric components

1998 ◽  
Vol 16 (7) ◽  
pp. 838-846 ◽  
Author(s):  
A. S. Kirillov
Keyword(s):  
Experimental Data ◽  
Energy Transfer ◽  
Vibrational Energy ◽  
Relaxation Times ◽  
Atmospheric Composition ◽  
Rate Coefficients ◽  
Frequency Change ◽  
Vibrational Energy Transfer ◽  
Ion Chemistry ◽  
Vibrationally Excited

Abstract. The first-order perturbation approximation is applied to calculate the rate coefficients of vibrational energy transfer in collisions involving vibrationally excited molecules in the absence of non-adiabatic transitions. The factors of molecular attraction, oscillator frequency change, anharmonicity, 3-dimensionality and quasiclassical motion have been taken into account in the approximation. The analytical expressions presented have been normalized on experimental data of VT-relaxation times in N2 and O2 to obtain the steric factors and the extent of repulsive exchange potentials in collisions N2-N2 and O2-O2. The approach was applied to calculate the rate coefficients of vibrational-vibrational energy transfer in the collisions N2-N2, O2-O2 and N2-O2. It is shown that there is good agreement between our calculations and experimental data for all cases of energy transfer considered.Key words. Ionosphere (Auroral ionosphere; ion chemistry and composition). Atmospheric composition and structure (Aciglow and aurora).

A Study on the Luminescent Properties and Energy Transfer of Na2BaMgP2O8:Tb3+, Eu3+ Phosphor

2014 ◽  
Vol 700 ◽  
pp. 113-116
Author(s):  
Yu Jie Chen ◽  
Feng Lan Han ◽  
Zhao Luo
Keyword(s):  
Energy Transfer ◽  
Solid State ◽  
Powder Diffraction ◽  
Luminescent Properties ◽  
Solid State Lighting ◽  
Diffraction Measurement ◽  
Effective Energy ◽  
X Ray ◽  
Red Color ◽  
Effective Energy Transfer

Na2BaMgP2O8phosphors were synthesized by a standard solid state reaction and their luminescent properties were investigated. The phase structure was analyzed by X-ray powder diffraction measurement. Under the excitation of 365nm, Na2BaMgP2O8:Tb3+, Eu3+phosphors show two color bands of green and red color due to5D4−7F5transition of Tb3+ions and5D0−7F2transition of Eu3+ions, respectively. The emission intensity of Tb3+deceased with the increasing concentration of Eu3+, which verified that an effective energy transfer occurred from Tb3+to Eu3+in Na2BaMgP2O8host. The present study indicated that the phosphors have a high potential application in solid state lighting.

Sign in / Sign up

Export Citation Format

Share Document