Nitrogen concentration and anisotropic effects on the EPR spectra of natural diamonds

CrystEngComm ◽  
2021 ◽  
Author(s):  
Ira Litvak ◽  
Haim Cohen ◽  
Yaakov Anker ◽  
Sharon Ruthstein
Keyword(s):  
Epr Spectroscopy ◽  
Nitrogen Concentration ◽  
Epr Spectra ◽  
Paramagnetic Centers ◽  
Natural Diamonds

EPR spectroscopy of pre-color treated natural diamonds – yellow and green: correlation between natural pre colored diamond paramagnetic centers and nitrogen concentration.

scholarly journals Effect of microwave power on EPR spectra of natural and synthetic dental biocompatible materials

Nukleonika ◽  
2015 ◽  
Vol 60 (3) ◽  
pp. 449-453
Author(s):  
Jakub Adamczyk ◽  
Paweł Ramos ◽  
Barbara Pilawa
Keyword(s):  
Epr Spectroscopy ◽  
Microwave Power ◽  
Lattice Relaxation ◽  
Biocompatible Materials ◽  
Spin Lattice Relaxation ◽  
Epr Spectra ◽  
Natural Material ◽  
Relaxation Processes ◽  
Paramagnetic Centers ◽  
Natural And Synthetic

Abstract Paramagnetic centers in the two exemplary synthetic and natural dental biocompatible materials applied in implantology were examined by the use of an X-band (9.3 GHz) electron paramagnetic resonance (EPR) spectroscopy. The EPR spectra were measured in the range of microwave power 2.2–70 mW. The aims of this work were to compare paramagnetic centers concentrations in different dental biocompatible materials and to determine the effect of microwave power on parameters of their EPR spectra. It is the very first and innovatory examination of paramagnetic centers in these materials. It was pointed out that paramagnetic centers existed in both natural (~1018 spin/g) and synthetic (~1019 spin/g) dental biocompatible materials, but the lower free radical concentration characterized the natural sample. Continuous microwave saturation of EPR spectra indicated that faster spin-lattice relaxation processes existed in synthetic dental biocompatible materials than in natural material. Linewidths (ΔBpp) of the EPR spectra of the natural dental material slightly increased for the higher microwave powers. Such effect was not observed for the synthetic material. The broad EPR lines (ΔBpp): 2.4 mT, 3.9 mT, were measured for the natural and synthetic dental materials, respectively. Probably strong dipolar interactions between paramagnetic centers in the studied samples may be responsible for their line broadening. EPR spectroscopy is the useful experimental method in the examination of paramagnetic centers in dental biocompatible materials.

Properties of electrochemically generated primary cationradicals of phenyl- and 2-(4-tolyl)-1,3,4,7-tetramethylisoindoles

1980 ◽  
Vol 45 (6) ◽  
pp. 1669-1676 ◽  
Author(s):  
Pavel Kubáček
Keyword(s):  
Electrochemical Oxidation ◽  
Spin Polarization ◽  
High Spin ◽  
Epr Spectroscopy ◽  
Half Life ◽  
Electrochemical Behaviour ◽  
Epr Spectra ◽  
Electrochemical Generation ◽  
Splitting Constant ◽  
Reduced Temperature

The first step of electrochemical oxidation of 2-phenyl- and 2-(4-tolyl)-1,3,4,7-tetramethylisoindoles in anhydrous acetonitrile produces relatively stable cationradicals which have been studied by means of EPR spectroscopy using the method of internal electrochemical generation of radicals under reduced temperature. The same electrochemical behaviour of the both studied derivatives and identical EPR spectra of their cationradicals can be explained within the Huckel MO method. The largest contribution to the magnitude of splitting constant of nitrogen nucleus is due to π-σ-spin polarization of C-N bonds caused by high spin abundance of pz-AO of carbon atoms. Half-life of decomposition of the studied cationradicals is 4 min at -30°C.

scholarly journals EPR Spectroscopy as a Tool to Characterize the Maturity Degree of Humic Acids

Materials ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3410
Author(s):  
Bozena Debska ◽  
Ewa Spychaj-Fabisiak ◽  
Wiesław Szulc ◽  
Renata Gaj ◽  
Magdalena Banach-Szott
Keyword(s):  
Humic Acids ◽  
Epr Spectroscopy ◽  
Plant Material ◽  
Crop Residues ◽  
Triticum Aestivum L ◽  
Epr Spectra ◽  
Thuja Plicata ◽  
Anthropogenic Factors ◽  
Paramagnetic Resonance ◽  
Spin Concentration

The major indicator of soil fertility and productivity are humic acids (HAs) arising from decomposition of organic matter. The structure and properties of HAs depend, among others climate factors, on soil and anthropogenic factors, i.e., methods of soil management. The purpose of the research undertaken in this paper is to study humic acids resulting from the decomposition of crop residues of wheat (Triticum aestivum L.) and plant material of thuja (Thuja plicata D.Don.ex. Lamb) using electron paramagnetic resonance (EPR) spectroscopy. In the present paper, we report EPR studies carried out on two types of HAs extracted from forest soil and incubated samples of plant material (mixture of wheat straw and roots), both without soil and mixed with soil. EPR signals obtained from these samples were subjected to numerical analysis, which showed that the EPR spectra of each sample could be deconvoluted into Lorentzian and Gaussian components. It can be shown that the origin of HAs has a significant impact on the parameters of their EPR spectra. The parameters of EPR spectra of humic acids depend strongly on their origin. The HA samples isolated from forest soils are characterized by higher spin concentration and lower peak-to-peak width of EPR spectra in comparison to those of HAs incubated from plant material.

Radiation Defects in Lime Mortars and Plasters Studied by EPR Spectroscopy

Radiocarbon ◽  
2020 ◽  
Vol 62 (3) ◽  
pp. 713-724
Author(s):  
Zuzanna Kabacińska ◽  
Danuta Michalska ◽  
Bernadeta Dobosz
Keyword(s):  
Epr Spectroscopy ◽  
Organic Radical ◽  
Radiation Defects ◽  
Paramagnetic Centers ◽  
Γ Irradiation ◽  
Paramagnetic Resonance ◽  
Crystalline Materials ◽  
Lime Mortars ◽  
Radiation Induced ◽  
Artificial Uv

ABSTRACTElectron paramagnetic resonance (EPR) spectroscopy is a well-established method of dating based on trapped charges, applied to various crystalline materials, including carbonates, bones, and teeth. It provides a detailed insight into the structure of radiation defects—paramagnetic centers generated by irradiation, without the need of a painstaking sample preparation, often challenging in other methods. Using EPR we studied the effect of γ radiation on lime mortars and plasters from ancient settlement Hippos in Israel, in order to analyze the process of defect generation. Analysis of the complex spectra revealed the presence of radiation-induced species, including CO2–, NO32– and organic radical. Using an artificial UV source, we generated relatively strong signals of paramagnetic centers, analogous to those created by γ irradiation, reaching their maximum intensity after 5–6 hr of UV exposure. Our results confirm the previous reports that radiation defects can also be generated, instead of bleached, in calcite by UV radiation, which is crucial for identifying the issues related to light exposition, affecting the accuracy of age determinations in trapped-charge dating methods.

EPR spectra of Gd3+ ions and localized paramagnetic centers in La0.5Gd0.5Ba3Cu2O6+χ

2000 ◽  
Vol 341-348 ◽  
pp. 573-574 ◽  
Author(s):  
N. Guskos ◽  
V. Likodimos ◽  
J. Typek ◽  
M. Wabia ◽  
H. Fuks
Keyword(s):  
Epr Spectra ◽  
Paramagnetic Centers

EPR Spectra from “EPR-Silent” Species:  High-Frequency and High-Field EPR Spectroscopy of Pseudotetrahedral Complexes of Nickel(II)

2002 ◽  
Vol 41 (17) ◽  
pp. 4478-4487 ◽  
Author(s):  
J. Krzystek ◽  
Ju-Hyun Park ◽  
Mark W. Meisel ◽  
Michael A. Hitchman ◽  
Horst Stratemeier ◽  
...  
Keyword(s):  
Epr Spectroscopy ◽  
High Frequency ◽  
High Field ◽  
Epr Spectra

Paramagnetic centers in graphite oxide according to EPR spectra and DFT calculations

2020 ◽  
Vol 754 ◽  
pp. 137722
Author(s):  
Andrey Kh Vorobiev ◽  
Dmitriy A. Astvatsaturov ◽  
Alexander V. Fionov ◽  
Natalia A. Chumakova
Keyword(s):  
Dft Calculations ◽  
Graphite Oxide ◽  
Epr Spectra ◽  
Paramagnetic Centers

Paramagnetic centers with S=5/2 in irradiated natural diamonds

1978 ◽  
Vol 19 (2) ◽  
pp. 327-328
Author(s):  
V. A. Nadolinnyi ◽  
M. Ya. Shcherbakova ◽  
E. V. Sobolev
Keyword(s):  
Paramagnetic Centers ◽  
Natural Diamonds

A general procedure for simulating EPR spectra of partially oriented paramagnetic centers

1979 ◽  
Vol 36 (2) ◽  
pp. 259-268 ◽  
Author(s):  
James C Swartz ◽  
Brian M Hoffman ◽  
Raymond J Krizek ◽  
Dimitrios K Atmatzidis
Keyword(s):  
General Procedure ◽  
Epr Spectra ◽  
Paramagnetic Centers
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