Time resolved magnetic modulation of ion recombination in organic solutions: spin motion in radical ion pairs

1977 ◽  
Vol 55 (11) ◽  
pp. 2102-2106 ◽  
Author(s):  
Jean Klein ◽  
René Voltz
Keyword(s):  
Solid Solutions ◽  
Organic Liquid ◽  
Ion Pairs ◽  
Lattice Relaxation ◽  
Solute Concentration ◽  
High Energy ◽  
Spin Lattice Relaxation ◽  
Time Resolved ◽  
Spin Lattice ◽  
Organic Solutions

The evolution of the singlet character of correlated ion radical pairs, prepared by high energy impact (3 particles) in organic liquid and solid solutions, is monitored by nanosecond time resolved solute recombination fluorescence. Results obtained show that the relative variations [IB(t) − I0(t)]/I0(t) of the luminescence intensity in presence IB(t) and in absence I0(t) of magnetic fields (B < 5 kG) decrease exponentially with time, according to a field and solute concentration dependent rate, in liquid but not in solid solutions; in the case of 2b PPD as solute, a damped oscillating component could be observed. The results are interpreted in terms of hyperfine interaction induced coherent singlet–triplet mixing and of field and solute concentration dependent spin–lattice relaxation.

Normal and anomalous nuclear spin-lattice relaxation at high temperatures in Sc-H(D), Y-H, and Lu-H solid solutions

1995 ◽  
Vol 51 (6) ◽  
pp. 3503-3511 ◽  
Author(s):  
R. G. Barnes ◽  
J.-W. Han ◽  
D. R. Torgeson ◽  
D. B. Baker ◽  
M. S. Conradi ◽  
...  
Keyword(s):  
High Temperatures ◽  
Solid Solutions ◽  
Nuclear Spin ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
Spin Lattice ◽  
Nuclear Spin Lattice Relaxation

Role of the Heat Sink Layer Ta for Ultrafast Spin Dynamic Process in Amorphous TbFeCo Thin Films

SPIN ◽  
2017 ◽  
Vol 07 (01) ◽  
pp. 1740003
Author(s):  
Y. Ren ◽  
Z. Z. Zhang ◽  
T. Min ◽  
Q. Y. Jin
Keyword(s):  
Spin Dynamic ◽  
Heat Bath ◽  
Lattice Relaxation ◽  
Recovery Process ◽  
Alloy Film ◽  
Spin Lattice Relaxation ◽  
Second Step ◽  
Time Resolved ◽  
Spin Lattice ◽  
20 Nm

The ultrafast demagnetization processes (UDP) in Ta ([Formula: see text] nm)/TbFeCo (20 nm) films have been studied using the time-resolved magneto-optical Kerr effect (TRMOKE). With a fixed pump fluence of 2 mJ/cm2, for the sample without a Ta underlayer ([Formula: see text][Formula: see text]nm), we observed the UDP showing a two-step decay behavior, with a relatively longer decay time ([Formula: see text] around 3.0 ps in the second step due to the equilibrium of spin-lattice relaxation following the 4[Formula: see text] occupation. As a 10[Formula: see text]nm Ta layer is deposited, the two-step demagnetization still exists while [Formula: see text] decreases to [Formula: see text]1.9[Formula: see text]ps. Nevertheless, the second-step decay ([Formula: see text]) disappears as the Ta layer thickness is increased up to 20 nm, only the first-step UDP occurs within 500 fs, followed by a fast recovery process. The rapid magnetization recovery rate strongly depends on the pump fluence. We infer that the Ta layer provides conduction electrons involving the thermal equilibrium of spin-lattice interaction and serves as heat bath taking away energy from spins of TbFeCo alloy film in UDP.

14N Nuclear Magnetic Resonance Relaxation of the Nitrate Ion and Ion Pairing in Aqueous Solution

1995 ◽  
Vol 48 (2) ◽  
pp. 207 ◽  
Author(s):  
G Owens ◽  
P Guarilloff ◽  
BJ Steel ◽  
T Kurucsev
Keyword(s):  
Aqueous Solution ◽  
Ion Pairs ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
Metal Nitrate ◽  
Spin Lattice Relaxation ◽  
Spin Lattice ◽  
Fast Exchange ◽  
Resonance Relaxation ◽  
Two State Model

14 N n.m.r. spin-lattice relaxation times of four metal nitrate salts were measured as a function of concentration in aqueous solution. The concentration dependence of T1 was attributed to the formation of ion pairs with increasing concentration in these solutions. The T1 data, allowing for viscosity corrections, were treated by a two-state model of 'free' and 'bound' nitrate ions and to both possibilities of slow and fast exchange between the two states. In the equilibrium expressions estimates of the relevant activity coefficients were included. The slow nitrate exchange mechanism was favoured and the values obtained for this particular mechanism compared well with those derived from alternative measurements.

scholarly journals Comparison of Structure and Local Dynamics of Two Peptide Dendrimers with the Same Backbone but with Different Side Groups in Their Spacers

Polymers ◽  
2020 ◽  
Vol 12 (8) ◽  
pp. 1657 ◽  
Author(s):  
Sofia Mikhtaniuk ◽  
Valeriy Bezrodnyi ◽  
Oleg Shavykin ◽  
Igor Neelov ◽  
Nadezhda Sheveleva ◽  
...  
Keyword(s):  
Ion Pairs ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
Spin Lattice ◽  
Peptide Dendrimers ◽  
Wide Range ◽  
Dynamics Method ◽  
Perform Computer Simulation ◽  
Good Agreement

In this paper, we perform computer simulation of two lysine-based dendrimers with Lys-2Lys and Lys-2Gly repeating units. These dendrimers were recently studied experimentally by NMR (Sci. Reports, 2018, 8, 8916) and tested as carriers for gene delivery (Bioorg. Chem., 2020, 95, 103504). Simulation was performed by molecular dynamics method in a wide range of temperatures. We have shown that the Lys-2Lys dendrimer has a larger size but smaller fluctuations as well as lower internal density in comparison with the Lys-2Gly dendrimer. The Lys-2Lys dendrimer has larger charge but counterions form more ion pairs with its NH 3 + groups and reduce the bare charge and zeta potential of the first dendrimer more strongly. It was demonstrated that these differences between dendrimers are due to the lower flexibility and the larger charge (+2) of each 2Lys spacers in comparison with 2Gly ones. The terminal CH2 groups in both dendrimers move faster than the inner CH2 groups. The calculated temperature dependencies of the spin-lattice relaxation times of these groups for both dendrimers are in a good agreement with the experimental results obtained by NMR.

scholarly journals 81Br and 27Al NQR of AlBr3 · 2C5H5N, AlBr3 · 1.5CH3CN, and AlBr3 · 2CH3CN

1986 ◽  
Vol 41 (1-2) ◽  
pp. 230-235 ◽  
Author(s):  
Koji Yamada ◽  
Tsutomu Okuda ◽  
Hisao Negita
Keyword(s):  
Ion Pairs ◽  
Relaxation Times ◽  
Structural Models ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
Reorientational Motion ◽  
Metal Ligands ◽  
Spin Lattice ◽  
Solid Compounds ◽  
Nqr Parameters

81Br NQR was studied in AlBr3 · 2C5H5N, AlBr3 · 1.5CH3CN, and AlBr3 · 2CH3CN. From the NQR spectra it is apparent that the solid compounds are build up by ion pairs [AlBr2(C5H5N )4+, AlBr4-], [Al(CH3CN)63+, 3AlBr4-], and [AlBr(CH3CN)52+, 2AlBr4-- CH3CN], respectively. 27Al NQR detected by SEDOR technique supports these structural models. Using these NQR parameters, the metal-ligands interactions in the six-coordinated complexes is discussed on the basis of the donor strength. In the case of AlBr3 ·2CH3CN two types of reorientational motion of the AlBr4- tetrahedra were detected from the spin lattice relaxation times and from fade-out phenomena of the 81Br NQR signals.

An electron spin resonance and CIDEP study of the primary processes in the photoreductions of furaldehyde, furyl methyl ketone, and acetylthiophene by phenols

1981 ◽  
Vol 59 (1) ◽  
pp. 116-122 ◽  
Author(s):  
Kuang S. Chen ◽  
Jeffrey K. S. Wan
Keyword(s):  
Double Bond ◽  
Methyl Ketone ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
Triplet States ◽  
Time Resolved ◽  
Spin Lattice ◽  
Carbon Double Bond ◽  
Photochemical Systems

The primary processes in the photoreduction of 2-furaldehyde, 2-furyl methyl ketone, and 2-acetylthiophene by phenol, 2,6-di-tert-butylphenol, and pentachlorophenol, respectively, were studied by esr and time-resolved CIDEP techniques. These furan derivatives, in their excited triplet states, can abstract a hydrogen atom from phenol via either the carbonyl group or the carbon–carbon double bond. The present results suggest that they all behave in the primary processes predominantly as carbonyl compounds. The spin–lattice relaxation times of all transient and polarized radicals observed in these photochemical systems were estimated by the CIDEP technique. The photoreductions of furaldehyde and furyl methyl ketone were also examined by high-field CIDNP. The nuclear polarization is mainly due to the cage products and the results are consistent with triplet carbonyl abstraction mechanism. Secondary radical addition to the carbon–carbon double bond of the furan ring was also observed in the furaldehyde–phenol system.

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