The Decrease of the ESEEM Frequency of $${\text{P}}_{700}^{ + } {\text{A}}_{1}^{ - }$$ P 700 + A 1 - Ion-Radical Pair in Photosystem I Embedded in Trehalose Glassy Matrix at Room Temperature can be Explained by Acceleration of Spin–Lattice Relaxation

2018 ◽  
Vol 49 (9) ◽  
pp. 1011-1025 ◽  
Author(s):  
A. A. Sukhanov ◽  
M. D. Mamedov ◽  
K. Möbius ◽  
A. Yu. Semenov ◽  
K. M. Salikhov
Keyword(s):  
Photosystem I ◽  
Room Temperature ◽  
Radical Pair ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
Glassy Matrix ◽  
Spin Lattice

scholarly journals Temperature and Pressure Variation of the Cl-NQR in A2PbCl6-Crystals

1986 ◽  
Vol 41 (1-2) ◽  
pp. 311-314 ◽  
Author(s):  
Y. M. Seo ◽  
J. Pelzl ◽  
C. Dimitropoulos
Keyword(s):  
Relaxation Rate ◽  
Room Temperature ◽  
Lattice Relaxation ◽  
Pressure Variation ◽  
Mixed Crystals ◽  
Spin Lattice Relaxation ◽  
Structural Transitions ◽  
Spin Lattice Relaxation Rate ◽  
Spin Lattice ◽  
Temperature And Pressure

The 35Cl NQR frequency and spin-lattice relaxation rate in the compounds A2PbCl6 (A = Cs, Rb, NH4, K) have been investigated in the range 4.2 K to 500 K, and as a function of pressure at room temperature. NQR experiments conducted on (K: NH4)2PbCl6 mixed crystals have been used to complete the NQR-frequency versus temperature diagram of K2PbCl6, revealing two structural transitions at Tc1 ≅ 358 K and at TC2 ≅ 333 K.

NUCLEAR MAGNETIC RELAXATION IN GAS MIXTURES

1962 ◽  
Vol 40 (8) ◽  
pp. 1027-1035 ◽  
Author(s):  
D. Llewelyn Williams
Keyword(s):  
Room Temperature ◽  
Lattice Relaxation ◽  
Lattice Relaxation Time ◽  
Proton Spin ◽  
Spin Lattice Relaxation ◽  
Spin Lattice ◽  
Gas Molecules ◽  
De Broglie Wavelength ◽  
Diffraction Effects ◽  
Good Agreement

Measurements of the proton spin–lattice relaxation time using pulse techniques have been made on the hydrogen–nitrogen, hydrogen–neon, and hydrogen–helium systems from room temperature to 60° K. The results are in good agreement with the Oppenheim–Bloom theory and illustrate the importance of the radial distribution of the gas molecules and of diffraction effects associated with the de Broglie wavelength.

NQR Relaxation Studies on Halogenomethyl Groups in Halogenoacetates

1998 ◽  
Vol 53 (6-7) ◽  
pp. 480-483 ◽  
Author(s):  
Maria Zdanowska-Fnjczek
Keyword(s):  
Room Temperature ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
Effect Of Temperature ◽  
Relaxation Theory ◽  
Temperature Range ◽  
Spin Lattice ◽  
Relaxation Studies

Abstract The effect of temperature on the chlorine NQR spin-lattice relaxation times in CsH(ClH2-CCOO)2 , KH(Cl3 CCOO) 2 and N(CH3)4 H(ClF2CCOO)2 has been studied in the temperature range 77 K to room temperature. The results were discussed on the basis of NQR relaxation theory.

81Br Nuclear Quadrupole Relaxation in Aluminium Tribromide

1995 ◽  
Vol 50 (8) ◽  
pp. 737-741 ◽  
Author(s):  
Noriaki Okubo ◽  
Mutsuo Igarashi ◽  
Ryozo Yoshizaki
Keyword(s):  
Room Temperature ◽  
Lattice Relaxation ◽  
Lattice Relaxation Time ◽  
Spin Lattice Relaxation ◽  
Quadrupole Relaxation ◽  
Spin Lattice ◽  
Raman Process ◽  
Nuclear Spin Lattice Relaxation ◽  
Nuclear Quadrupole ◽  
Nuclear Quadrupole Relaxation

Abstract The 81Br nuclear spin-lattice relaxation time in AlBr3 has been measured between 8 K and room temperature. The result is analyzed using the theory of the Raman process based on covalency. A Debye temperature of 67.6 K and covalency of 0.070 and 0.072 for terminal and 0.022 for bridging bonds are obtained. The correspondence of the latter values to those obtained from the NQR frequencies is low, in contrast to the previously examined compounds.

Molecular Motion in Tetraphenyltin Studied by NMR

1999 ◽  
Vol 54 (8-9) ◽  
pp. 488-494
Author(s):  
A. Pajzderska ◽  
J. Wąsicki ◽  
S. Lewicki
Keyword(s):  
Phenyl Ring ◽  
Room Temperature ◽  
Molecular Motion ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
Spin Lattice ◽  
Ring Rotation ◽  
Phenyl Rings ◽  
Correlated Motion

NMR second moment and spin-lattice relaxation times in the laboratory (60 and 25 MHz) and in therotating frame (B1 = 2.1 mT) were studied for polycrystalline tetraphenyltin Sn(C6H5)4 in a wide temperaturerange. Two kinds of motions were detected: isotropic rotation of whole molecules and reorientations/oscillations of phenyl rings. A dependence of the potential energy of the molecule in the crystalon the angle of the phenyl ring rotation about the Sn-C bond was obtained on the basis of atom-atomcalculations. The amplitude of the ring-oscillations at 133 K was estimated as ± 7°. Below room temperaturethe magnetisation recovery is significantly non-exponential, which may be interpreted as dueto the correlated motion of phenyl rings.

NQR and Phase Transitions of Tetramethylammonium Tetrahalogenomercurates (II)

1996 ◽  
Vol 51 (5-6) ◽  
pp. 755-760 ◽  
Author(s):  
Hiromitsu Terao ◽  
Tsutomu Okuda ◽  
Koji Yamada ◽  
Hideta Ishihara ◽  
Alarich Weiss
Keyword(s):  
Phase Transitions ◽  
Room Temperature ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
Temperature Phase ◽  
Reorientational Motion ◽  
Spin Lattice ◽  
Increasing Temperature

NQR and DTA revealed phase transitions in [(CH3)4N] 2HgBr4 and [(CH3)4N] 2HgI4 at 272 K and 264 K, respectively. The NQR resonance lines faded out with increasing temperature. From preliminary measurements of 81Br NQR spin-lattice relaxation times and 199Hg NMR a reorientational motion of HgBr4 ions around one of their pseudo C3 axes in the room temperature phase of [(CH3)4N] 2HgBr4 is suggested.

MOLECULAR REORIENTATION IN FERROELECTRIC LITHIUM HYDRAZINIUM SULPHATE

1967 ◽  
Vol 45 (10) ◽  
pp. 3257-3263 ◽  
Author(s):  
W. D. MacClement ◽  
M. Pintar ◽  
H. E. Petch
Keyword(s):  
Low Temperatures ◽  
Room Temperature ◽  
Lattice Relaxation ◽  
Lattice Relaxation Time ◽  
Resonance Absorption ◽  
Spin Lattice Relaxation ◽  
Kcal Mole ◽  
Molecular Reorientation ◽  
Hindered Rotation ◽  
Spin Lattice

The temperature dependence of the spin-lattice relaxation time T1 and of the second moment of the magnetic-resonance absorption signal has been determined for protons in powdered lithium hydrazinium sulphate over the range 80–480 °K. These measurements indicate that the hydrazinium ion is rigid only at very low temperatures. As the temperature is raised, the −NH3 group begins to undergo hindered rotation about the N–N axis with an activation energy of 4.2 kcal/mole and the effect of this motion on the line width becomes pronounced in the region of 85 °K. Further molecular reorientation begins above room temperature and is probably reorientation of the −NH2 group about either the N–N axis or the bisectrix of the H–N–H angle. Above 435 °K the hydrazinium ion begins to tumble about several axes and at 480 °K diffuses through the structure.

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