OPTICAL FARADAY ROTATION STUDIES OF PARAMAGNETIC RESONANCE AND RELAXATION IN PRASEODYMIUM ETHYLSULPHATE

1965 ◽  
Vol 43 (12) ◽  
pp. 2361-2373 ◽  
Author(s):  
David J. Griffiths ◽  
Hans Glättli
Keyword(s):  
Hyperfine Structure ◽  
Liquid Helium ◽  
Faraday Rotation ◽  
Broad Band ◽  
Relaxation Times ◽  
Electron System ◽  
Epr Spectrum ◽  
Paramagnetic Resonance ◽  
Helium Bath ◽  
Half Power

The technique of detecting electron paramagnetic resonance and measuring paramagnetic relaxation times at liquid-helium temperatures by the magneto-optical Faraday rotation has been applied to the even number (4f2) electron system of Pr3+ in praseodymium ethylsulphate (PrES). The EPR spectrum (X band) of undiluted PrES at 1.37 °K is a broad band extending over several kilo-gauss with no evidence of hyperfine structure. The band intensity decreases at [Formula: see text] and covers [Formula: see text] from its maximum to half-power point. The absence of any hyperfine structure indicates that crystal-field distortion is the main source of line broadening.The relaxation times measured as a function of temperature over the range 1.40 to 2.18 °K and at 4.22 °K range from 0.1 to 10 msec. For [Formula: see text], τ decreases from 0.40 to 0.15 msec, is proportional to T−(3.5 ± 0.6), and is considered to be the phonon–bath relaxation time. Values of τ show a scatter within 0.20 ± 0.02 msec for [Formula: see text]. Near the λ point [Formula: see text], τ exhibits a very rapid increase, having a value of 0.20 msec at 2.155 °K and 0.85 msec at 2.165 °K. This behavior appears to be related to the energy exchange between the crystal and liquid-helium bath. Measurements of τ at 2.18 °K and 4.22 °K indicate that the rate at which the spin–phonon system returns to initial thermal equilibrium is governed by the thermal conductivity of the liquid-helium bath.

Synthesis and photophysical properties of new Ln(III) (Ln = Eu(III), Gd(III), or Tb(III)) complexes of 1-amidino-O-methylurea

2014 ◽  
Vol 68 (2) ◽  
Author(s):  
L. Singh ◽  
R. Singh
Keyword(s):  
Uv Light ◽  
Photophysical Properties ◽  
Broad Band ◽  
Green Emission ◽  
Spectroscopic Studies ◽  
Emission Characteristic ◽  
Central Metal ◽  
Epr Spectrum ◽  
Paramagnetic Resonance ◽  
The Eu

AbstractThree new solid lanthanide(III) complexes, [Ln(1-AMUH)3] · (NO3)3 (1-AMUH = 1-amidino-O-methylurea; Ln = Eu(III), Gd(III), or Tb(III)) were synthesised and characterised by elemental analysis, infrared spectra, magnetic moment measurement, and electron paramagnetic resonance (EPR) spectra for Gd(III) complex. The formation of lanthanide(III) complexes is confirmed by the spectroscopic studies. The photophysical properties of Gd(III), Eu(III), and Tb(III) complexes in solid state were investigated. The Tb(III) complex exhibits the strongest green emission at 543 nm and the Eu(III) complex shows a red emission at 615 nm while the Gd(III) complex shows a weak emission band at 303 nm. Under excitation with UV light, these complexes exhibited an emission characteristic of central metal ions. The powder EPR spectrum of the Gd(III) complex at 300 K exhibits a single broad band with g = 2.025. The bi-exponential nature of the decay lifetime curve is observed in the Eu(III) and Tb(III) complexes. The results reveal them to have potential as luminescent materials.

Radiation Effects on Hollandite Ceramics developed for Radioactive Cesium Immobilization

2003 ◽  
Vol 792 ◽  
Author(s):  
V. Aubin ◽  
D. Caurant ◽  
D. Gourier ◽  
N. Baffier ◽  
S. Esnouf ◽  
...  
Keyword(s):  
Radiation Effects ◽  
Liquid Waste ◽  
Fission Products ◽  
Radioactive Cesium ◽  
Radioactive Liquid Waste ◽  
Epr Spectrum ◽  
Paramagnetic Resonance ◽  
Γ Radiation ◽  
The Stability ◽  
High Level

ABSTRACTProgress on separating the long-lived fission products from the high level radioactive liquid waste (HLW) has led to the development of specific host matrices, notably for the immobilization of cesium. Hollandite (nominally BaAl2Ti6O16), one of the main phases constituting Synroc, receives renewed interest as specific Cs-host wasteform. The radioactive cesium isotopes consist of short-lived Cs and Cs of high activities and Cs with long lifetime, all decaying according to Cs+→Ba2++e- (β) + γ. Therefore, Cs-host forms must be both heat and (β,γ)-radiation resistant. The purpose of this study is to estimate the stability of single phase hollandite under external β and γ radiation, simulating the decay of Cs. A hollandite ceramic of simple composition (Ba1.16Al2.32Ti5.68O16) was essentially irradiated by 1 and 2.5 MeV electrons with different fluences to simulate the β particles emitted by cesium. The generation of point defects was then followed by Electron Paramagnetic Resonance (EPR). All these electron irradiations generated defects of the same nature (oxygen centers and Ti3+ ions) but in different proportions varying with electron energy and fluence. The annealing of irradiated samples lead to the disappearance of the latter defects but gave rise to two other types of defects (aggregates of light elements and titanyl ions). It is necessary to heat at relatively high temperature (T=800°C) to recover an EPR spectrum similar to that of the pristine material. The stability of hollandite phase under radioactive cesium irradiation during the waste storage is discussed.

scholarly journals Purification and Characterization of an Iron Superoxide Dismutase and a Catalase from the Sulfate-Reducing BacteriumDesulfovibrio gigas

2000 ◽  
Vol 182 (3) ◽  
pp. 796-804 ◽  
Author(s):  
Wagner G. Dos Santos ◽  
Isabel Pacheco ◽  
Ming-Yih Liu ◽  
Miguel Teixeira ◽  
António V. Xavier ◽  
...  
Keyword(s):  
Superoxide Dismutase ◽  
High Spin ◽  
Specific Activity ◽  
Ligand Field ◽  
Strictly Anaerobic ◽  
Oxygen Utilization ◽  
Epr Spectrum ◽  
Paramagnetic Resonance ◽  
Sulfate Reducing ◽  
Link Type

ABSTRACT The iron-containing superoxide dismutase (FeSOD; EC 1.15.1.1 ) and catalase (EC 1.11.1.6 ) enzymes constitutively expressed by the strictly anaerobic bacterium Desulfovibrio gigas were purified and characterized. The FeSOD, isolated as a homodimer of 22-kDa subunits, has a specific activity of 1,900 U/mg and exhibits an electron paramagnetic resonance (EPR) spectrum characteristic of high-spin ferric iron in a rhombically distorted ligand field. Like other FeSODs from different organisms, D. gigas FeSOD is sensitive to H2O2 and azide but not to cyanide. The N-terminal amino acid sequence shows a high degree of homology with other SODs from different sources. On the other hand, D. gigas catalase has an estimated molecular mass of 186 ± 8 kDa, consisting of three subunits of 61 kDa, and shows no peroxidase activity. This enzyme is very sensitive to H2O2and cyanide and only slightly sensitive to sulfide. The native enzyme contains one heme per molecule and exhibits a characteristic high-spin ferric-heme EPR spectrum (g y,x = 6.4, 5.4); it has a specific activity of 4,200 U/mg, which is unusually low for this class of enzyme. The importance of these two enzymes in the context of oxygen utilization by this anaerobic organism is discussed.

Evaluation of systemic blood NO dynamics by EPR spectroscopy: HbNO as an endogenous index of NO

2003 ◽  
Vol 285 (2) ◽  
pp. H589-H596 ◽  
Author(s):  
Kazuyoshi Kirima ◽  
Koichiro Tsuchiya ◽  
Hiroyoshi Sei ◽  
Toyoshi Hasegawa ◽  
Michiyo Shikishima ◽  
...  
Keyword(s):  
Endothelial Dysfunction ◽  
Whole Blood ◽  
Computer Assisted ◽  
Subtraction Method ◽  
Epr Spectrum ◽  
Systemic Blood ◽  
Paramagnetic Resonance ◽  
Species Overlap ◽  
Epr Signal ◽  
Electron Paramagnetic

The measurement of hemoglobin-nitric oxide (NO) adduct (HbNO) in whole blood by the electron paramagnetic resonance (EPR) method seems relevant for the assessment of systemic NO levels. However, ceruloplasmin and unknown radical species overlap the same magnetic field as that of HbNO. To reveal the EPR spectrum of HbNO, we then introduced the EPR signal subtraction method, which is based on the computer-assisted subtraction of the digitized EPR spectrum of HbNO-depleted blood from that of sample blood using the software. Rats were treated with Nω-nitro-l-arginine methyl ester (l-NAME; 120 mg · kg–1 · day–1) for 1 wk to obtain HbNO-depleted blood. When this method was applied to the analysis of untreated fresh whole blood, the five-coordinate state of HbNO was observed. HbNO concentration in pentobarbital-anesthetized rats was augmented (change in [HbNO] = 1.6–5.5 μM) by infusion of l-arginine (0.2–0.6 g/kg) but not d-arginine. Using this method, we attempted to evaluate the effects of temocapril on HbNO dynamics in an l-NAME-induced rat endothelial dysfunction model. The oral administration of l-NAME for 2 wk induced a serious hypertension, and the HbNO concentration was reduced (change in [HbNO] = 5.7 μM). Coadministration of temocapril dose dependently improved both changes in blood pressure and the systemic HbNO concentration. In this study, we succeeded in measuring the blood HbNO level as an index of NO by the EPR HbNO signal subtraction method. We also demonstrated that temocapril improves abnormalities of NO dynamics in l-NAME-induced endothelial dysfunction rats using the EPR HbNO signal subtraction method.

scholarly journals Zero- and Nonzero-Nuclear-Spin Isotope Response in Resonantly Enhanced Multiphoton Ionization of Kr nd Xe With Broad Band Lasers

1993 ◽  
Vol 13 (2) ◽  
pp. 159-165
Author(s):  
D. Charalambidis ◽  
Y. L. Shao ◽  
S. D. Moustaizis ◽  
C. Fotakis
Keyword(s):  
Hyperfine Structure ◽  
Nuclear Spin ◽  
Intermediate State ◽  
Broad Band ◽  
Multiphoton Ionization ◽  
Mass Analysis ◽  
Experimental Conditions ◽  
Broadband Laser ◽  
Photon Ionization ◽  
Ionization Response

The abundance of the 83Kr isotope, determined by ion mass analysis following three photon resonant four photon ionization via the 5s’ [1/2]1 state with a broadband laser is found to differ from the expected natural value. This effect is discussed in terms of a change of the ionization response due to the decay of coherence in the intermediate state to its hyperfine structure coupling. The nonzero nuclear spin isotopes of Xe have not shown any effect of this type in three different ionization schemes under the present experimental conditions.

Spin reorientation transition and spin dynamics study of perovskite orthoferrite TmFeO3 detected by electron paramagnetic resonance

2020 ◽  
Vol 22 (37) ◽  
pp. 21403-21411
Author(s):  
Poorva Sharma ◽  
Jiyu Fan ◽  
Ashwini Kumar ◽  
Arvind Yogi ◽  
Yisheng Chai ◽  
...  
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Spin Dynamics ◽  
Spin Reorientation ◽  
Epr Spectrum ◽  
Paramagnetic Resonance ◽  
Spin Reorientation Transition ◽  
Different Temperatures ◽  
Electron Paramagnetic

(Right) EPR spectrum of TmFeO3 from 20–300 K. (Left) (a) Asymmetry behavior w.r.t. temperature (K), (b) ΔHppvs. T, (c) Plot as ln(ΔHpp × T) vs. 1000/T, (d) DIN (inset represents χdcvs. T at different temperatures).

scholarly journals Concentration of Fe(3+)-Triapine in BEAS-2B Cells

2019 ◽  
Vol 20 (12) ◽  
pp. 3062 ◽  
Author(s):  
William E. Antholine ◽  
Charles R. Myers
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Tumor Cells ◽  
Iron Uptake ◽  
Antitumor Agent ◽  
Epr Spectrum ◽  
Paramagnetic Resonance ◽  
Epr Method ◽  
First Time ◽  
Electron Paramagnetic ◽  
In Cells

An electron paramagnetic resonance (EPR) method was used to determine the concentration of the antitumor agent Triapine in BEAS-2B cells when Triapine was bound to iron (Fe). Knowledge of the concentration of Fe-Triapine in tumor cells may be useful to adjust the administration of the drug or to adjust iron uptake in tumor cells. An EPR spectrum is obtained for Fe(3+)-Triapine, Fe(3+)(Tp)2+, in BEAS-2B cells after addition of Fe(3+)(Tp)2+. Detection of the low spin signal for Fe(3+)(Tp)2+ shows that the Fe(3+)(Tp)2+ complex is intact in these cells. It is proposed that Triapine acquires iron from transferrin in cells including tumor cells. Here, it is shown that iron from purified Fe-transferrin is transferred to Triapine after the addition of ascorbate. To our knowledge, this is the first time that the EPR method has been used to determine the concentration of an iron antitumor agent in cells.

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