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Sample records for electron-spin resonance study

  1. Selectivity of alkyl radical formation from branched alkanes studied by electron spin resonance and electron spin echo spectroscopy

    International Nuclear Information System (INIS)

    Tsuneki, Ichikawa; Hiroshi, Yoshida

    1992-01-01

    Alkyl radicals generated from branched alkanes by γ radiation are being measuring by electron spin resonance and electron spin echo spectroscopy. This research is being conducted to determine the mechanism of selective alkyl radical formation in low-temperature solids

  2. Electron spin resonance intercomparison studies on irradiated foodstuffs

    International Nuclear Information System (INIS)

    Raffi, J.

    1992-01-01

    The results of intercomparison studies organized by the Community Bureau of Reference on the use of electron spin resonance spectroscopy for the identification of irradiated food are presented. A qualitative intercomparison was carried out using beef and trout bones, sardine scales, pistachio nut shells, dried grapes and papaya. A quantitative intercomparison involving the use of poultry bones was also organized. There was no difficulty in identifying meat bones, dried grapes and papaya. In the case of fish bones there is a need for further kinetic studies using different fish species. The identification of pistachio nut shells is more complicated and further research is needed prior to the organization of a further intercomparison. Laboratories were able to distinguish between chicken bones irradiated in the range 1 to 3 KGy or 7 to 10 KGy although there was a partial overlap between the results from different laboratories

  3. Electron spin resonance intercomparison studies on irradiated foodstuffs

    Energy Technology Data Exchange (ETDEWEB)

    Raffi, J [CEA Centre d` Etudes de Cadarache, 13 - Saint-Paul-lez-Durance (FR)

    1992-07-01

    The results of intercomparison studies organized by the Community Bureau of Reference on the use of electron spin resonance spectroscopy for the identification of irradiated food are presented. A qualitative intercomparison was carried out using beef and trout bones, sardine scales, pistachio nut shells, dried grapes and papaya. A quantitative intercomparison involving the use of poultry bones was also organized. There was no difficulty in identifying meat bones, dried grapes and papaya. In the case of fish bones there is a need for further kinetic studies using different fish species. The identification of pistachio nut shells is more complicated and further research is needed prior to the organization of a further intercomparison. Laboratories were able to distinguish between chicken bones irradiated in the range 1 to 3 KGy or 7 to 10 KGy although there was a partial overlap between the results from different laboratories.

  4. Electron spin resonance study of radicals in irradiated polyethylene

    International Nuclear Information System (INIS)

    Fujimura, Takashi

    1979-02-01

    In order to elucidate radiation effect in polyethylene, the nature and behavior of radicals produced in polyethylene and the model compound of polyethylene irradiated at 77 0 K were studied by using electron spin resonance. The structure of radical pairs, which are composed of two radicals produced very closely each other, was investigated in drawn polyethylene and the single crystal of n-eicosane. The radical pairs of intrachain type and interchain type were found in polyethylene and n-eicosane respectively. It was suggested that these two types of radical pairs are the precursors of double bonds and crosslinks respectively. The thermal decay reactions of radicals themselves produced in irradiated polyethylene were investigated. It was made clear that the short range distances between two radicals play an important role in the decay reaction of alkyl radicals at low temperatures. The trapping regions of radicals were studied and it was clarified that allyl radicals, which are produced by the reaction of alkyl radicals with double bonds, are trapped both in the crystalline and non-crystalline regions. (author)

  5. Electron Spin Resonance (ESR) studies of returned comet nucleus samples

    International Nuclear Information System (INIS)

    Tsay, Fundow; Kim, S.S.; Liang, R.H.

    1989-01-01

    The most important objective of the Comet Nucleus Sample Returm Mission is to return samples which could reflect formation conditions and evolutionary processes in the early solar nebula. It is expected that the returned samples will consist of fine-grained silicate materials mixed with ices composed of simple molecules such as H 2 O, NH 3 , CH 4 as well as organics and/or more complex compounds. Because of the exposure to ionizing radiation from cosmic-ray, gamma-ray, and solar wind protons at low temperature, free radicals are expected to be formed and trapped in the solid ice matrices. The kind of trapped radical species together with their concentration and thermal stability can be used as a dosimeter as well as a geothermometer to determine thermal and radiation histories as well as outgassing and other possible alternation effects since the nucleus material was formed. Since free radicals that are known to contain unpaired electrons are all paramagnetic in nature, they can be readily detected and characterized in their native form by the Electron Spin Resonance (ESR) method. In fact, ESR has been shown to be a non-destructive, highly sensitive tool for the detection and characterization of paramagnetic, ferromagnetic, and radiation damage centers in terrestrial and extraterrestrial geological samples. The potential use of ESR as an effective method in the study of returned comet nucleus samples, in particular, in the analysis of fine-grained solid state icy samples is discussed

  6. Electron spin resonance

    International Nuclear Information System (INIS)

    Wasson, J.R.; Salinas, J.E.

    1980-01-01

    Published literature concerning electron spin resonance (ESR) from July 1977 to July 1979 is reviewed. The 108 literature sources cited were chosen from literally thousands and are intended to serve as a guide to the current literature and to provide an eclectic selection of publications cited for their contributions to the advance and/or applications of ESR spectroscopy. 40 of the sources are reviews, and a table is included to indicate the topic(s) mainly covered in each review. Other divisions of the material reviewed are apparatus and spectral analysis, analytical applications, and selected paramagnetic materials

  7. Study of γ-irradiated lithographic polymers by electron spin resonance and electron nuclear double resonance

    International Nuclear Information System (INIS)

    Schlick, S.; Kevan, L.

    1982-01-01

    The room temperature gamma irradiation degradation of the lithographic polymers, poly(methylmethacrylate) (PMMA), poly(methyl-α-chloroacrylate) (PMCA), poly(methyl-α-fluoroacrylate) (PMFA), and poly(methylacrylonitrile) (PMCN), have been studied by electron spin resonance and electron nuclear double resonance (ENDOR) to assess their molecular degradation processes of relevance to electron beam lithography. Two classes of radicals are found, chain radicals and chain scission radicals. PMMA and PMCA mainly form chain scission radicals consistent with degradation while for PMCN the resolution is poorer, and this is only probable. PMFA forms mainly chain radicals consistent with predominant crosslinking. The total radical yield is greatest in PMCA and PMCN. ENDOR is used to assess the compactness of the radiation degradation region for PMMA and PMCA and hence the potential resolution of the resist; this appears to be about the same for these methacrylate polymers

  8. Electron spin resonance studies of some irradiated pharmaceuticals

    International Nuclear Information System (INIS)

    Gibella, M.; Crucq, A-S.; Tilquin, B.; Stocker, P.; Lesgards, G.; Raffi, J.

    2000-01-01

    Five antibiotics belonging to the cephalosporins and penicillins groups have been irradiated: anhydrous ampicilline acid, amoxicilline acid trihydrate, cefuroxime sodium salt, cloxacilline sodium salt monohydrate and ceftazidime pentahydrate. ESR studies have been carried out, showing the influence of irradiation and storage parameters on the nature and concentration of the free radicals trapped. These results may be used to detect an irradiation treatment on such pharmaceuticals. (author)

  9. Electron spin resonance study of the demagnetization fields of the ferromagnetic and paramagnetic films

    Directory of Open Access Journals (Sweden)

    I.I. Gimazov, Yu.I. Talanov

    2015-12-01

    Full Text Available The results of the electron spin resonance study of the La1-xCaxMnO3 manganite and the diphenyl-picrylhydrazyl thin films for the magnetic field parallel and perpendicular to plane of the films are presented. The temperature dependence of the demagnetizing field is obtained. The parameters of the Curie-Weiss law are estimated for the paramagnetic thin film.

  10. Study by electron spin resonance of the free radicals created under irradiation in glycine

    International Nuclear Information System (INIS)

    Thomet, P.; Rassat, A.; Servoz-Gavin, P.; Choudens, H. de

    1967-01-01

    The free radicals created by different radiations in glycine are measured by electron spin resonance and their number is evaluated in function of the absorbed dose. This number decreases when the LET of the radiations increases ; in other words,high LET radiations gives less radiochemical effects; in contrary with the fact that high LET radiations creates more damage in biological materials. The decreasing with time of the number of free radicals and the speed of this decrease is a function of temperature; by the study of the kinetics of this decrease, an attempt has been made to prove the presence of three radicals. (authors) [fr

  11. Electron Spin Resonance Spectroscopy for Studying the Generation and Scavenging of Reactive Oxygen Species by Nanomaterials

    Science.gov (United States)

    Yin, Jun-Jie; Zhao, Baozhong; Xia, Qingsu; Fu, Peter P.

    2013-09-01

    One fundamental mechanism widely described for nanotoxicity involves oxidative damage due to generation of free radicals and other reactive oxygen species. Indeed, the ability of nanoscale materials to facilitate the transfer of electrons, and thereby promote oxidative damage or in some instances provide antioxidant protection, may be a fundamental property of these materials. Any assessment of a nanoscale material's safety must therefore consider the potential for toxicity arising from oxidative damage. Therefore, rapid and predictive methods are needed to assess oxidative damage elicited by nanoscale materials. The use of electron spin resonance (ESR) to study free radical related bioactivity of nanomaterials has several advantages for free radical determination and identification. Specifically it can directly assess antioxidant quenching or prooxidant generation of relevant free radicals and reactive oxygen species. In this chapter, we have reported some nonclassical behaviors of the electron spin relaxation properties of unpaired electrons in different fullerenes and the investigation of anti/prooxidant activity by various types of nanomaterials using ESR. In addition, we have reviewed the mechanisms of free radical formation photosensitized by different nanomaterials. This chapter also included the use of spin labels, spin traps and ESR oximetry to systematically examine the enzymatic mimetic activities of nanomaterials.

  12. Study Free Radical Of Irradiated Pulasari (Alexyia reinwadrtii BI) By Using Electron Spin Resonance (ESR)

    International Nuclear Information System (INIS)

    Erizal; Chosdu, Rahayu

    2000-01-01

    In the effort to develop the application of gamma irradiation for medicinal plant preservation especially for seeds i.e. pulasari (Alyxia reinwardtii Bi), the characteristic of free radical of irradiated pulasari (water content 4-6%) at doses of 10; 20; 30 kGy after storage time ranged 0-70 days were studied by using electron spin resonance. It was found that with increasing irradiation dose, the yield of free radicals formation increase. The yield of free radical of pulasari powder more lower than in a chips state. With increasing storage time up 5 days, the yield of free radical decrease up to 60-70 %. At storage time up to 70 days, the free radical remained ranged 10-20%, relatively

  13. Electron spin resonance studies of iron-group impurities in beryllium fluoride glasses

    Energy Technology Data Exchange (ETDEWEB)

    Griscom, D L; Stapelbroek, M [Naval Research Lab., Washington, DC (USA); Weber, M J [California Univ., Livermore (USA). Lawrence Livermore National Lab.

    1980-11-01

    Electron spin resonance investigations have been carried out on unirradiated BeF/sub 2/ glasses. Two relatively intense resonances were observed in a water-free distilled glass known to contain 49 ppM Ni, 13 ppM Mn, and < 20 ppM Fe. One of these was the paramagnetic resonance spectrum of Mn/sup 2 +/. Analysis of the observed /sup 19/F superhyperfine structure demonstrated this manganese to occupy distorted octahedral sites in the glass network. The second resonance was shown by temperature and frequency dependence studies, coupled with computer line shape analysis, to be a ferromagnetic resonance signal due to precipitated ferrite phases. The data suggest that these ferrites are somewhat heterogeneous and most likely comprize magnetite-like phases similar to NiFe/sub 2/O/sub 4/. An optical extinction curve rising into the ultraviolet with an approximate lambda/sup -4/ dependence is tentatively ascribed to light scattering by ferrite particles approximately 1000 Angstroems in diameter.

  14. Silver atom solvation and desolvation in ice matrices: study of solvation shell geometry by electron spin resonance and electron spin echo methods

    Energy Technology Data Exchange (ETDEWEB)

    Kevan, L; Narayana, P A

    1978-01-01

    Results of studies of the solvation shell structure of silver atoms in ice matrix at 4/sup 0/K by electron spin resonance (ESR) and electron spin echo spectrometry are reported. Drastic change in the hyperfine coupling constant of the silver atom was noted when the silver atom initially produced at 4/sup 0/K was warmed to 77/sup 0/K and reexamined by ESR at 4/sup 0/K. This suggested a very drastic rearrangement of the water molecules surrounding the silver atom. The geometric arrangement of water molecules around the silver atom produced at 4/sup 0/K was what would be expected for a solvated silver ion, indicating that no rearrangement had occurred after the silver atom formed. The addition of a little thermal excitation (heating to 77/sup 0/K) results in the geometry changes than can be explained by assuming either that a water molecule rotates around one of its OH bands or by the development of a hydrogen bond between the silver atom and one of the first solvation shell water molecules. Optical excitation in the absorption band of the silver atom in the ice matrix at 400nm resulted in desolvation of the silver ion or a reversion to the structure originally obtained by reaction of solver salts in ic matrix with radiation produced electrons. This was best explained by a charge transfer mechanism. (BLM)

  15. Electron spin resonance and electron spin echo modulation spectroscopic studies on the structure and reactivity of Pd(I) species in SAPO-11 molecular sieves

    International Nuclear Information System (INIS)

    Chul Wee Lee; Jong-Sung Yu; Kevan, L.

    1992-01-01

    This paper explores the possibility of using Pd ions in SAPO-11 by adding [Pd(NH 3 ) 4 ] 2+ during the synthesis of SAPO-11 to form PdSAPO-11, which is compared with solid-state ion exchange PdSAPO-11 and impregnation PdH-SAPO-11 in which palladium is in an extraframework position. Electron spin resonance and electron spin echo modulation spectroscopies are used to determine if the palladium position in PdSAPO-11 is located in a framework or extraframework

  16. The electron spin resonance study of heavily nitrogen doped 6H SiC crystals

    Czech Academy of Sciences Publication Activity Database

    Savchenko, Dariia

    2015-01-01

    Roč. 117, č. 4 (2015), "045708-1"-"045708-6" ISSN 0021-8979 R&D Projects: GA ČR GP13-06697P; GA MŠk(CZ) LM2011029 Grant - others:SAFMAT(XE) CZ.2.16/3.1.00/22132 Institutional support: RVO:68378271 Keywords : electron spin resonance * conduction electrons * 6H SiC * insulator-metal transition Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.101, year: 2015

  17. Electron spin resonance studies of gamma irradiated saccharides. Etudes par resonance paramagnetique electronique de saccharides soumis a un rayonnement gamma

    Energy Technology Data Exchange (ETDEWEB)

    Raffi, J.; Thiery, C.; Battesti, C.; Agnel, J.P.; Triolet, J.; Vincent, P. (CEA Centre d' Etudes de Cadarache, 13 - Saint-Paul-lez-Durance (France). Dept. de Physiologie Vegetale et Ecosystemes)

    1993-04-01

    The radiolysis mechanism of several saccharides was studied in order to understand the radiolysis mechanism of starches. Electron Spin Resonance first performed in powder state did not allow determination of the chemical structure of the induced radicals. The spin-trapping method combined with HPLC however, followed by ESR spectra analysis with the 'Voyons' simulation program was applied to the study of glucose, glucose oligomers and disaccharides. We were thus able to further our understanding of the radiolysis mechanism of starches. 2 tabs., 4 figs.

  18. Electron Spin Resonance studies on PS, PP and PS/PP blends under gamma irradiation

    International Nuclear Information System (INIS)

    Reyes, J.; Claro, M.; Albano, C.; Venezuela Central University, Caracas; Moronta, D.

    2002-01-01

    Complete text of publication follows. Electron Spin Resonance (ESR) studies on Polystyrene (PS), Polypropylene (PP) and their mixtures at compositions of 80/20 with and without a compatibilizer (SBS in block), 7.5 wt.%, irradiated with gamma rays from a Cobalt-60 source with a dose rate of 4.8 KGy/h at integral doses of radiation of 10, 25, 50, 60, 70, 400, 800 and 1300 KGy in the presence of air and at room temperature (RT) are reported. The dependence of resonance line width, Hpp; resonance line shapes K, and radical concentration, S, with the integral dose of irradiation is investigated. The nature of the free radicals after ten days of air storage is discussed. The free radical concentration, the double integral of the resonance line, S, has been estimated at room temperature, RT, for a group of single lines, characterized by the same giromagnetic, g, value by direct numerical double integration. In the samples studied no spectrum of 0 kGy of integral dose was observed. The concentration of radicals, S, observed when the integral radiation doses was increased, presents a maximum value in the PP samples at high doses (70-1300 kGy) and minimum values in the PS samples with the same doses. This shows that the PP degrades at a faster rate than the PS, owing to the presence of the bencenic ring in the latter. In the PS/PP mixtures studied with and without compatibilizer, the values of the radical concentration is found between the observed values in the homopolymers, being closer to the PS, which might imply that the presence of PS decays the degradation process of the PP in the mixture

  19. Electron spin resonance dosimetric properties of bone

    International Nuclear Information System (INIS)

    Caracelli, I.; Terrile, M.C.; Mascarenhas, S.

    1986-01-01

    The characteristics of electron spin resonance (ESR) dosimetry using bovine bone samples are described. The number of paramagnetic centers created by gamma radiation in the inorganic bone matrix was measured as a function of absorbed dose. The minimum detectable dose was 0.5 Gy for 60Co gamma rays. The response was linear up to the maximum dose studied (30 Gy) and independent of dose rate up to the maximum dose rate used (1.67 Gy min-1). For different bone samples the reproducibility was 5%. This method may be valuable for nuclear accident dosimetry

  20. Electron spin resonance of particulate soot samples from automobiles to help environmental studies

    International Nuclear Information System (INIS)

    Yamanaka, C.; Matsuda, T.; Ikeya, M.

    2005-01-01

    The application of electron spin resonance (ESR) was studied for diesel soot samples and suspended particulate matter (SPM) from automobile engines. Soot samples or diesel exhaust particles (DEP) were recovered at various points: in the exhaust pipe of a diesel engine, at the dust sampler of a highway tunnel (standard DEP), on the soundproofing wall alongside a heavy traffic road, and on the filters of a dust sampler for SPM. The diesel soot samples apparently showed two ESR spectra: one was a broad spectrum at g=2.1 with a line width of ca. 80-120mT and the other was a sharp signal of a carbon radical at g=2.003 with a line width of 0.4mT. Annealing experiments with a DEP sample at 250 deg. C revealed drastic enhancement of the sharp ESR signal, which suggested a thermal process of carbonization of remnant organics. An oximetric study by ESR showed an enhancement of the broad signal in the diesel soot sample as well as in the sharp ESR signal. Therefore, the main part of the broad ESR signal would be attributed to carbon radicals, which form a different configuration, probably closely interacting aggregates. Enhancement of the sharp ESR signal was not observed in the standard DEP sample under vacuum condition, which suggested less adsorption sites on the surface of DEP samples

  1. Electron spin resonance study on γ-ray-induced ethyl radical in ethane hydrate

    International Nuclear Information System (INIS)

    Takeya, Kei; Nango, Kouhei; Sugahara, Takeshi; Ohgaki, Kazunari; Tani, Atsushi; Ito, Hironori; Okada, Michio; Kasai, Toshio

    2007-01-01

    Electron spin resonance (ESR) studies have been performed to investigate radicals induced in ethane hydrate irradiated by γ-rays at 77K. Two ESR spectra are observed and identified as the induced ethyl radical (g=2.0031±0.0005, A α sub(perpendicular)=2.2±0.1mT, A α sub(parallel)=2.5±0.1mT, A β =2.7±0.1mT) and induced atomic hydrogen (g=2.0026±0.0005, A=50.5±0.1mT). From the results of ESR analysis and gas mass spectroscopy, it is concluded that the ethyl radical decays into butane by dimerization in the first-order reaction in the temperature region of 250-265K. The activation energy of the decay reaction is 73.1±6.3kJ/mol, which is near the dissociation enthalpy change of ethane hydrate to liquid water and gaseous ethane. This finding implies that ethane hydrate does not dissociate into ice but supercooled water in the present temperature region, similar to the dissociation of methane hydrate in our previous study. (author)

  2. Electron spin resonance study on γ-ray-induced radical species in ethylene hydrate

    International Nuclear Information System (INIS)

    Takeya, Kei; Sugahara, Takeshi; Ohgaki, Kazunari; Tani, Atsushi

    2007-01-01

    Electron spin resonance (ESR) study on γ-irradiated synthetic ethylene hydrate was performed to investigate induced radicals and their thermal stability. ESR spectra of induced 3-butenyl radical (.CH 2 C 2 H 3 =CH 2 ,g=2.0039±0.0005,A α =2.2±0.1mTandA β =3.0±0.1mT) and induced ethyl radical (.C 2 H 5 , g=2.0044±0.0005, A α =2.2±0.1mT and A β =2.7±0.1mT) were observed in irradiated ethylene hydrate. The decay of the 3-butenyl radicals was observed above 200 K with the activation energy of 51.9±4.4kJ/mol. The obvious decay of ethyl radicals starts above 240 K that is close to the dissociation temperature of ethylene hydrate at atmospheric pressure. The activation energy of the ethyl radical decay is estimated as 63.4±8.2kJ/mol and nearly equal to the enthalpy change of ethylene hydrate into liquid water and gaseous ethylene. It is suggested that the decay of ethyl radicals would be caused by the hydrate dissociation and that ethylene hydrate dissociates into water (supercooled) and ethylene at 240-265 K.

  3. Thermoluminescence and electron spin resonance studies of irradiated biological single crystals

    International Nuclear Information System (INIS)

    Cooke, D.W.

    1977-01-01

    Single crystals of x-irradiated L-alanine:Cr 3+ have been studied between 90 and 300K by electron spin resonance (ESR) and thermoluminescence (TL) techniques. Ultraviolet (uv) photobleaching of the Cr 3+ electron traps and L-alanine radical centers was also investigated. The results demonstrate that the x-ray generated radical centers can be destroyed by uv-induced electron transport activity, and this destruction follows first order kinetics. Also, the transformation of the primary neutral radical species to a secondary radical in L-alanine was found not to be induced by intermolecular electron transport. The TL glow was determined to proceed by first-order kinetics at a temperature of 160K with an activation energy of 0.3 eV and a frequency factor of 1.0 x 10 8 s -1 . The emission spectrum consisted of a broad band (FWHM approx. = 100 nm) which peaked at approximately 420 nm. Scintillation activity was observed in the ferroelectric crystals triglycine sulfate (TGS), deuterated TGS, and TGS: L-alanine. The emission spectrum of TGS:L-alanine was obtained. New observations of scintillations and current pulses from glycine, a nonferroelectric crystal, which result from heating or cooling the sample between 77 and 300K with no previous irradiation were made. The scintillations and current pulses occur approximately in coincidence. Scintillations were also observed from the potent oncogen 3-hydroxyxanthine by cooling the sample from 300 to 90K with no previous irradiation

  4. Electron spin resonance scanning tunneling microscope

    International Nuclear Information System (INIS)

    Guo Yang; Li Jianmei; Lu Xinghua

    2015-01-01

    It is highly expected that the future informatics will be based on the spins of individual electrons. The development of elementary information unit will eventually leads to novel single-molecule or single-atom devices based on electron spins; the quantum computer in the future can be constructed with single electron spins as the basic quantum bits. However, it is still a great challenge in detection and manipulation of a single electron spin, as well as its coherence and entanglement. As an ideal experimental tool for such tasks, the development of electron spin resonance scanning tunneling microscope (ESR-STM) has attracted great attention for decades. This paper briefly introduces the basic concept of ESR-STM. The development history of this instrument and recent progresses are reviewed. The underlying mechanism is explored and summarized. The challenges and possible solutions are discussed. Finally, the prospect of future direction and applications are presented. (authors)

  5. Theoretical foundations of electron spin resonance

    CERN Document Server

    Harriman, John E

    2013-01-01

    Theoretical Foundations of Electron Spin Resonance deals with the theoretical approach to electron paramagnetic resonance. The book discusses electron spin resonance in applications related to polyatomic, probably organic, free radicals in condensed phases. The book also focuses on essentially static phenomena, that is, the description and determination of stationary-state energy levels. The author reviews the Dirac theory of the electron in which a four-component wave function is responsible for the behavior of the electron. The author then connects this theory with the nonrelativistic wave f

  6. Electron spin resonance (ESR) studies on irradiated cocoa beans and niger seeds

    International Nuclear Information System (INIS)

    Mangaonkar, S.R.; Natarajan, V.; Sastry, M.D.; Desai, S.R.P.; Kulkarni, P.R.

    1997-01-01

    Electron spin resonance (ESR) spectra of irradiated (10kGy) and unirradiated cocoa beans and niger seeds have been compared. Unirradiated cocoa beans failed to give any ESR signal, whereas after irradiation (10kGy) an ESR signal at g = 2.0042 was observed. However, ESR signals are given by both irradiated and unirradiated niger seeds. The intensity of signal was found to be dose-dependent up to 10kGy for both seeds. The signals were stable up to 180 days in both cases. The results indicate the possibility of using ESR for distinguishing between irradiated and unirradiated cocoa beans but not for niger seeds

  7. Mechanism of free radical generation in platelets and primary hepatocytes: A novel electron spin resonance study.

    Science.gov (United States)

    Wang, Chiun-Lang; Yang, Po-Sheng; Tsao, Jeng-Ting; Jayakumar, Thanasekaran; Wang, Meng-Jiy; Sheu, Joen-Rong; Chou, Duen-Suey

    2018-01-01

    Oxygen free radicals have been implicated in the pathogenesis of toxic liver injury and are thought to be involved in cardiac dysfunction in the cirrhotic heart. Therefore, direct evidence for the electron spin resonance (ESR) detection of how D‑galactosamine (GalN), an established experimental hepatotoxic substance, induced free radicals formation in platelets and primary hepatocytes is presented in the present study. ESR results demonstrated that GalN induced hydroxyl radicals (OH•) in a resting human platelet suspension; however, radicals were not produced in a cell free Fenton reaction system. The GalN‑induced OH• formation was significantly inhibited by the cyclooxygenase (COX) inhibitor indomethasin, though it was not affected by the lipoxygenase (LOX) or cytochrome P450 inhibitors, AA861 and 1‑aminobenzotriazole (ABT), in platelets. In addition, the present study demonstrated that baicalein induced semiquinone free radicals in platelets, which were significantly reduced by the COX inhibitor without affecting the formed OH•. In the mouse primary hepatocytes, the formation of arachidonic acid (AA) induced carbon‑centered radicals that were concentration dependently enhanced by GalN. These radicals were inhibited by AA861, though not affected by indomethasin or ABT. In addition, GalN did not induce platelet aggregation prior to or following collagen pretreatment in human platelets. The results of the present study indicated that GalN and baicalein may induce OH• by COX and LOX in human platelets. GalN also potentiated AA induced carbon‑centered radicals in hepatocytes via cytochrome P450. The present study presented the role of free radicals in the pathophysiological association between platelets and hepatocytes.

  8. Simultaneous electrochemical-electron spin resonance studies of carotenoid cation radicals and dications

    International Nuclear Information System (INIS)

    Khaled, M.; Hadjipetrou, A.; Xinhai Chen; Kispert, L.

    1989-01-01

    Carotenoids are present in the chloroplasts of photosynthetic green plants and serve as photoprotect devices and antenna pigments, and active role in the photosynthetic electron-transport chain with the carotenoid cation radical as an integral part of the electron-transfer process. The research reported herein has confirmed that carotenoid cation radicals have a lifetime that is sensitive to solvent, being longest in CH 2 Cl 2 and are best prepared electrochemically. Semiempirical AM1 and INDO calculations of the trans and cis isomers of β-carotene, canthaxanthin and β-apo-8'-carotenal cation radicals predicted the unresolved EPR line whose linewidth varies to a measurable degree with carotenoid, which subsequent experimental observations affirmed. Simultaneous electrochemical - electron spin resonance studies of carotenoid cation radicals and dications have shown the radicals detected by EPR are formed by the one electron oxidation of the carotenoid, that dimers are not formed upon decay of the radical cations and an estimate of the rate of comproportionation as a function of carotenoid can be given. The formal rate constant K' for heterogenous electron transfer rate at the electrode surface has been deduced from rotating disc experiments. Upon deuteration, and in the presence of excess β-carotene, the half-life for decay of the carotenoid radical cation increased an order of magnitude due to the reaction between diffusion carotenoid dications and carotenoids to form additional radical cations. The carotenoid diffusion coefficients deduced by chronocoulometry substantiates this measurement. The produces formed upon electrochemical studies are being studied by HPLC and the isomers formed thermally are being separated. Additional radical reactions are currently being studied by EPR and electrochemical methods

  9. A study on the characteristics of enamel to electron spin resonance spectrum for retrospective dosimetry

    International Nuclear Information System (INIS)

    Hong, Dae Seok; Lee, Kun Jai

    2003-01-01

    Electron Spin Resonance (ESR) spectroscopy is one of the methods applicable to retrospective dosimetry. The retrospective dosimetry is a part of dose reconstruction for estimation of exposed dose occurred years before the estimation. A tooth can be separated as enamel, dentine and cementum. Among the three parts, enamel is known as to show the best sensitivity to the absorbed dose and is most widely used. Since the later 80s, ESR dosimetry with tooth enamel has been studied and applied for the retrospective dosimetry. There are some factors affecting the sensitivity of enamel to absorbed dose. One of the factors is a size of enamel. Grain size of the 1.0mm∼0.1mm range is commonly used and 0.6mm∼0.25mm is recommended in other study. But the sensitivity can be varied by the grain size. In this study, the granular effect of enamel to the sensitivity is examined for application to retrospective dosimetry. In the enamel separation, to minimize the physically induced ESR spectrum, only chemical separation method was used. Separated enamels were divided by their size. The sizes of each sample is 1.0mm∼0.71mm, 0.5mm∼0.3mm, and below 0.1mm, respectively. All enamel samples show ESR spectrum related to the absorbed dose and the ESR spectrum shows linearity to the absorbed dose. The sensitivities are similar for each sample. But the enamel of size below 0.1mm shows poor characteristics relative to other enamel size. So, it is not recommended to use enamel samples below 0.1mm

  10. Electron-spin-resonance study of radiation-induced paramagnetic defects in oxides grown on (100) silicon substrates

    International Nuclear Information System (INIS)

    Kim, Y.Y.; Lenahan, P.M.

    1988-01-01

    We have used electron-spin resonance to investigate radiation-induced point defects in Si/SiO 2 structures with (100) silicon substrates. We find that the radiation-induced point defects are quite similar to defects generated in Si/SiO 2 structures grown on (111) silicon substrates. In both cases, an oxygen-deficient silicon center, the E' defect, appears to be responsible for trapped positive charge. In both cases trivalent silicon (P/sub b/ centers) defects are primarily responsible for radiation-induced interface states. In earlier electron-spin-resonance studies of unirradiated (100) substrate capacitors two types of P/sub b/ centers were observed; in oxides prepared in three different ways only one of these centers, the P/sub b/ 0 defect, is generated in large numbers by ionizing radiation

  11. Electron spin resonance studies of the mechanism of radiation damage to DNA

    International Nuclear Information System (INIS)

    Cullis, P.M.; Symons, M.C.R.

    1986-01-01

    Electron spin resonance spectroscopy has only been used successfully on dry DNA at room temperature or on aqueous DNA at low temperatures. Under these conditions the direct damage results in electron-loss, which initially is indiscriminate, but rapidly ends up as G dot + , which is stable up to ca. 210 0 K. Electrons are trapped at T, giving T dot - anions, which are converted into dot TH in the 130 to 208 0 K range. Above these temperatures, both centers decay without the clear appearance of other intermediate radicals. Arguments are given against the concept that holes and/or electrons are extensively mobile within DNA molecules, and also against the concept that the ionic species studied by ESR spectroscopy recombine to give G and T to a major extent. In the presence of oxygen, O 2 - ions were detected and the primary yield of T dot - was reduced. However, both primry centers were lost at relatively low temperatures, with the concomitant formation of RO 2 dot radicals. The fate of these and the O 2 dot - anions could not be determined by ESR spectroscopy. In the presence of hydrogen peroxide or iodoacetamide, electrons were effectively scavenged, giving dot OH and H 2 C dot ONH 2 radicals and a reduced yield of T dot - . These active radicals were rapidly converted into new alkyl-type radicals, thought to be primarily formed by hydrogen atom abstraction. The ESR signals due to these radicals were lost at temperatures below those characteristic of the primary centers. This shows that these may well have been converted into such alkyl radical centers by hydrogen atom transfer despite our inability to detect them. 17 refs., 7 figs

  12. Electron spin resonance identification of irradiated fruits

    International Nuclear Information System (INIS)

    Raffi, J.J.; Agnel, J.-P.L.

    1989-01-01

    The electron spin resonance spectrum of achenes, pips, stalks and stones from irradiated fruits (stawberry, raspberry, red currant, bilberry, apple, pear, fig, french prune, kiwi, water-melon and cherry) always displays, just after γ-treatment, a weak triplet (a H ∼30 G) due to a cellulose radical; its left line (lower field) can be used as an identification test of irradiation, at least for strawberries, raspberries, red currants or bilberries irradiated in order to improve their storage time. (author)

  13. Electron Spin Resonance Studies of Carbonic Anhydrase: Transition Metal Ions and Spin-Labeled Sulfonamides*

    Science.gov (United States)

    Taylor, June S.; Mushak, Paul; Coleman, Joseph E.

    1970-01-01

    Electron spin resonance (esr) spectra of Cu(II) and Co(II) carbonic anhydrase, and a spin-labeled sulfonamide complex of the Zn(II) enzyme, are reported. The coordination geometry of Cu(II) bound in the enzyme appears to have approximately axial symmetry. Esr spectra of enzyme complexes with metal-binding anions also show axial symmetry and greater covalency, in the order ethoxzolamide cyanide complex suggests the presence of two, and probably three, equivalent nitrogen ligands from the protein. Esr spectra of the Co(II) enzyme and its complexes show two types of Co(II) environment, one typical of the native enzyme and the 1:1 CN- complex, and one typical of a 2:1 CN- complex. Co(II) in the 2:1 complex appears to be low-spin and probably has a coordination number of 5. Binding of a spin-labeled sulfonamide to the active center immobilizes the free radical. The similarity of the esr spectra of spin-labeled Zn(II) and Co(II) carbonic anhydrases suggests that the conformation at the active center is similar in the two metal derivatives. PMID:4320976

  14. An electron spin resonance study of γ-ray irradiated pepper

    International Nuclear Information System (INIS)

    Ukai, Mitsuko; Hamaya, Naruki; Ichii, Akane; Abe, Aika

    2003-01-01

    Using electron spin resonance (ESR) spectroscopy, we revealed four radical species in the irradiated pepper. The representative ESR spectrum of the pepper is composed of a sextet centered at g=2.0, a singlet at the same g-value, a singlet at g=4.0 and side peaks near g=2.0. The first one is attributable to a signal with hyperfine (hf) interactions of Mn 2+ ion (hf constant=7.4 mT). The second one is due to an organic free radical that may be induced by the (γ-ray irradiation. The third one may be originated from Fe 3+ ion in the non-hem proteins. Those three signals were found in the pepper sample before irradiation. The fourth signals were found at the symmetric position of the organic free radical, i.e., the second signal. The progressive saturation method of the ESR microwave power indicated quite different relaxation behaviors of those radicals. The method reflects four independent radical species in the irradiated pepper. Relaxation time for the singlet signal centered at g=2.0 revealed that the signal is due to the typical organic free radical. (author)

  15. ESR (Electronic Spin Resonance Spectroscopy) study of irradiated paper for biomedical material wrapping

    International Nuclear Information System (INIS)

    Huarte, Monica; Rubin de Celis, Emilio; Kairiyama, Eulogia; Zapata, Miguel; Santoro, Natalia; Magnavacca, Cecilia

    2009-01-01

    Ionising radiation treatments are used for sterilization, microbiological decontamination, disinfection, insect disinfestation and food preservation. This ionising radiation generates free radicals (FR) in matter, which can be detected by Electronic Spin Resonance Spectroscopy (ESR). For this work it had analysed different kind of irradiated package papers of syringes, surgical gloves and dressings by ESR. These were irradiated with doses between 20 and 35 kGy of gamma radiation (Cobalt 60). The processed samples were measured in a Bruker ECS 106 spectrometer. The obtained results were: 1-) The irritated samples showed a central peak and two satellites induced by the applied radiation; 2-) The non-irradiated samples did not show the characteristic satellite peaks of the irritated ones; 3-) A linear relationship between the signal heights per unit mass and the applied doses was found; and 4-) The signals were highly stable, with half-time values between 240 and 370 days for 20 and 30 kGy, permitting more than one year of monitoring proceedings. In conclusion, the ESR allows the detection, quantification and time monitoring processes of this kind of irradiated materials. (author) [es

  16. Electron spin resonance investigations on polycarbonate irradiated with U ions

    Energy Technology Data Exchange (ETDEWEB)

    Chipara, M.I.; Reyes-Romero, J

    2001-12-01

    Electron spin resonance investigations on polycarbonate irradiated with uranium ions are reported. The dependence of the resonance line parameters (line intensity, line width, double integral) on penetration depth and dose is studied. The nature of free radicals induced in polycarbonate by the incident ions is discussed in relation with the track structure. The presence of severe exchange interactions among free radicals is noticed.

  17. A nuclear magnetic resonance and electron spin resonance study on the dynamics of pentacoordinated organophosphorus compounds

    International Nuclear Information System (INIS)

    Keijzer, A.E.H. de.

    1988-01-01

    In this thesis the role of the steric and electronic effects on the fundamental dynamic behaviour of pentacoordinated phosporus compounds is further elaborated. In chapter 2 a variable temperature 13 C NMR study, performed on a series of monocyclic oxyphosphoranes, is presented. The investigations were carried out to determine the influence of the conformational transmission effect on the barriers to pseudorotation in pentacoordinated phosphorus compounds. Chapter 3 also comprises a variable temperature 13 C NMR study on pentacoordinated phosphorus compounds. In this chapter, however, an additional high-resolution 1 H NMR study on the conformational equilibria around the P-O-C-C-O fragments is included. These studies were performed in order to determine whether the enhancement of the reorganization rates around phosphorus is brought about by accelerated pseudorotation or by the involvement of hexacoordinated zwitterionic phosphorus intermediates. In chapter 4, a 31 P NMR study on the solvolysis rate of several phosphinate esters is described. This study was performed in order to determine the influence of the conformational transmission effect on the solvolysis rate of phosphate esters. A number of phosphates is examined in which, during the course of the solvolysis reaction, the conformational transmission effect is bound to be present or absent respectively. Moreover, it is discussed in which way the concept of conformational transmission induced differences in solvolysis rates can be used as a probe to examine the reactions of biologically important phosphate esters. In chapters 5 and 6 ESR studies on the influence of steric and electronic factors on phosphoranyl formation in solution, and on the intramolecular electron transfer in phosphoranyl radicals are presented. (author). 121 refs.; 33 figs.; 17 figs

  18. Study by electron spin resonance (ESR) of 60 Co irradiated grains and farinaceous derivatives

    International Nuclear Information System (INIS)

    Catanni, Marta Mattos.

    1995-01-01

    The electron spin resonance (ESR) spectroscopy is being pointed out as one of the most promising techniques to determine whether a food has been irradiated. In this work, the ESR spectrum of paramagnetic radicals produced by gamma irradiation of grains and flour derivatives using a 60 Co source was investigated. Samples of grains (wheat and barley), flours (wheat, maniac, rye, soy bean and maize), bran and starch have been irradiated with doses between 0.2 and 70 KGy. It was shown that all varieties of grains and flours presented similar ESR spectra with variation in the free radicals signal intensity. Measurements at 9.5 and 34.5 GHz shown that spectra were composed probably by the superposition of four paramagnetic species with g-factors closed to that of the free electron (2 triplets, 1 doublet and 1 singlet). Hyperfine interactions and the correspondingly line widths were estimated through an spectrum computer simulation. It was established that ESR signal intensities increased with the irradiation dose for all samples. Up to the commercial admissible dose limit (1 kGy), the increase of ESR signal shown a linear behavior with the dose. The signal stability varied significantly with storage conditions and sample humidity. For 1 kGy-irradiated samples stored at room temperature and 14% humidity, the ESR radiation signals were possible to be detected up to 5 days after irradiation. When the same samples were stored at low temperatures (0 0 C) or freeze-dried (almost 0% humidity) the ESR signals were detected until 6 months after irradiation. Similar ESR spectrum found for grains and flours was obtained for diverse starchy food products. It was verified that it is possible to identify for a long time irradiated starchy foods when they are commercialized dehydrated or frozen. (author). 66 refs., 35 figs., 17 tabs

  19. Light-free magnetic resonance force microscopy for studies of electron spin polarized systems

    International Nuclear Information System (INIS)

    Pelekhov, Denis V.; Selcu, Camelia; Banerjee, Palash; Chung Fong, Kin; Chris Hammel, P.; Bhaskaran, Harish; Schwab, Keith

    2005-01-01

    Magnetic resonance force microscopy is a scanned probe technique capable of three-dimensional magnetic resonance imaging. Its excellent sensitivity opens the possibility for magnetic resonance studies of spin accumulation resulting from the injection of spin polarized currents into a para-magnetic collector. The method is based on mechanical detection of magnetic resonance which requires low noise detection of cantilever displacement; so far, this has been accomplished using optical interferometry. This is undesirable for experiments on doped silicon, where the presence of light is known to enhance spin relaxation rates. We report a non-optical displacement detection scheme based on sensitive microwave capacitive readout

  20. Positron annihilation and electron spin resonance studies of defects in electron-irradiated 3C-SiC

    International Nuclear Information System (INIS)

    Itoh, Hisayoshi; Yoshikawa, Masahito; Tanigawa, Shoichiro; Nashiyama, Isamu; Misawa, Shunji; Okumura, Hajime; Yoshida, Sadafumi.

    1992-01-01

    Defects induced by 1 MeV electron-irradiation in cubic silicon carbide (3C-SiC) epitaxially grown by chemical vapor deposition have been studied with positron annihilation and electron spin resonance (ESR). Doppler broadened energy spectra of annihilation γ-rays obtained by using variable-energy positron beams showed the formation of vacancy-type defects in 3C-SiC by the electron-irradiation. An ESR spectrum labeled Tl, which has an isotropic g-value of 2.0029 ± 0.001, was observed in electron-irradiated 3C-SiC. The Tl spectrum is interpreted by hyperfine interactions of paramagnetic electrons with 13 C at four carbon sites and 29 Si at twelve silicon sites, indicating that the Tl center arises from a point defect at a silicon site. Both the results can be accounted for by the introduction of isolated Si vacancies by the irradiation. (author)

  1. Electron Spin Resonance study of charge trapping in α-ZnMoO.sub.4./sub. single crystal scintillator

    Czech Academy of Sciences Publication Activity Database

    Buryi, Maksym; Spassky, D.A.; Hybler, Jiří; Laguta, Valentyn; Nikl, Martin

    2015-01-01

    Roč. 47, Sep (2015), 244-250 ISSN 0925-3467 R&D Projects: GA MŠk LO1409; GA MŠk(CZ) LM2011029; GA ČR GAP204/12/0805 Institutional support: RVO:68378271 Keywords : Electron Spin Resonance * scintillator * charge traps * zinc molybdate Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.183, year: 2015

  2. Electron spin resonance studies of radiation effects. Final report, 1964-1979 (including annual progress reports for 1978 and 1979)

    International Nuclear Information System (INIS)

    Rogers, M.T.

    1979-07-01

    The discovery of new free radicals, largely in irradiated single crystals of nonmetallic solids, and the determination of the molecular and electronic structures of these paramagnetic species by electron spin resonance (ESR) spectroscopy, have been carried out using a wide variety of organic and inorganic materials. The mechanisms of production of radicals in solids, their motions, and their reactions have been investigated and some applicable general principles deduced. Emphasis has been on aliphatic free radicals from irradiated carboxylic acids and amides and their halogen-substituted derivatives, organometallic radicals and substituted cyclic hydrocarbon radicals; inorganic radicals studied include V centers, hypervalent radicals and electron adducts. Extensive investigations of paramagnetic transition metal complexes, particularly cyanides and fluorides, have been made. In all cases quantum mechanical calculations have been employed as far as possible in interpreting the data. An improved method for analyzing experimental ESR spectra of single crystals has been developed and a number of crystal structures have been determined to supplement the ESR studies. Applications of nuclear quadrupole resonance spectroscopy to the study of structure and bonding in inorganic solids have been made and a method for using nuclear magnetic relaxation data for estimating quadrupole coupling constants in liquids has been developed

  3. Spectroscopy study of electron spin resonance of coal oxidation of different rank

    International Nuclear Information System (INIS)

    Enciso Prieto, Hector Manuel

    1992-01-01

    The present work constitutes an initial step for the knowledge of the coal oxidation, with the purpose of preventing the adverse influences caused by this phenomenon in the physical-chemical characteristics and in the tendency to the spontaneous combustion. Since the knowledge the influence of the free radicals in this process, their relative concentration was measured by means of the use of the technique of resonance spin electron. This technique measures the absorption of electromagnetic radiation, generally in the microwaves region, for the materials that not have electrons matched up in a strong magnetic field. In the essays of oxidation three coal of different range and different characteristics of mass were used and it was studied the influence of the temperature, particle size and the range. The results showed that the coal of Guacheta (bituminous low in volatile) it presents bigger concentration of free radicals, after the reaction with the atmospheric oxygen, with regard to the coal of the Cerrejon (bituminous high in volatile B) and Amaga (bituminous high in volatile C). Although this doesn't indicate that the coal of Guacheta is that more easily is oxidized, but rather it possibly presents stabilization of radicals for resonance. It concluded that there are differences in the oxidation mechanism between coal of different rank and different agglomeration properties

  4. Study of irradiation effects in the silicon carbide cubic polytype by photoluminescence and electron spin resonance spectroscopies

    International Nuclear Information System (INIS)

    Lefevre, J.

    2008-01-01

    This experimental work has consisted in the study of point defects induced by an electronic irradiation in the cubic crystallographic structure of silicon carbide with low temperature photoluminescence and electron spin resonance spectroscopies. The first one of these measurement tools has allowed to estimate the displacement threshold energy in the silicon sub-lattice and then to analyze the thermal stability of the irradiation defects in the low temperature range: (10-300 K) and then in the high temperature range: (300-1400 K). Besides, on the base of a recent theoretical model, this thesis has confirmed the proposition of the isolated silicon antisite for the D1 center whose running beyond the nominal running temperature of fission nuclear reactors (generation IV), for which SiC is in part intended, seems to be particularly problematic. Measurements carried out by ESR under lighting have at last allowed to detect a new defect in its metastable spin state S=1, possibly associated to a silicon interstitial configuration. (O.M.)

  5. Microscopic properties of degradation-free capped GdN thin films studied by electron spin resonance

    International Nuclear Information System (INIS)

    Shimokawa, Tokuro; Fukuoka, Yohei; Fujisawa, Masashi; Zhang, Weimin; Okubo, Susumu; Ohta, Hitoshi; Sakurai, Takahiro; Vidyasagar, Reddithota; Yoshitomi, Hiroaki; Kitayama, Shinya; Kita, Takashi

    2015-01-01

    The microscopic magnetic properties of high-quality GdN thin films have been investigated by electron spin resonance (ESR) and ferromagnetic resonance (FMR) measurements. Detailed temperature dependence ESR measurements have shown the existence of two ferromagnetic components at lower temperatures, which was not clear from the previous magnetization measurements. The temperature, where the resonance shift occurs for the major ferromagnetic component, seems to be consistent with the Curie temperature obtained from the previous magnetization measurement. On the other hand, the divergence of line width is observed around 57 K for the minor ferromagnetic component. The magnetic anisotropies of GdN thin films have been obtained by the analysis of FMR angular dependence observed at 4.2 K. Combining the X-ray diffraction results, the correlation between the magnetic anisotropies and the lattice constants is discussed

  6. Study of iron exchanged zeolites by Moessbauer effect and electron spin resonance spectroscopy

    International Nuclear Information System (INIS)

    Aguirre Campuzano, C.E.

    1993-01-01

    Crystalline iron exchanged NaY zeolites, prepared from aqueous solutions and calcined at atmospheric conditions, have been studied and characterized by XRD, Moessbauer and EPR spectroscopies and TGA analysis. Three iron sites are clearly distinguished from Moessbauer and EPR measurements. Firstly, characteristic Moessbauer and EPR spectra may arise from framework sites, suggesting that Fe has substituted Al. It is also found that their spectroscopic signals are not intensity affected by thermal treatments. Secondly, a Moessbauer doublet which may arise from octahedral sites in the large cavity of the zeolite, shows however, that this doublet and its EPR signal are intensity temperature affected. An additional line broadening is observed on the low velocity line of this doublet, Thirdly, characteristic Moessbauer and EPR signals, which are also intensity temperature dependent have been associated to accluded material, where the Moessbauer doublet presents the line broadening effect before mentioned. Such line broadening effect may be due to perturbing signals from iron ions in tetrahedral sites. Finally, it has been observed that during calcination of the FeY zeolites, the three characteristic EPR signals for the three iron sites, do not increase at the expenses of the other. A result that may suggest a strong bonding between Fe-site of the Y zeolite, irrespective of the iron source. (Author)

  7. Comparison effects and electron spin resonance studies of α-Fe2O4 spinel type ferrite nanoparticles.

    Science.gov (United States)

    Bayrakdar, H; Yalçın, O; Cengiz, U; Özüm, S; Anigi, E; Topel, O

    2014-11-11

    α-Fe2O4 spinel type ferrite nanoparticles have been synthesized by cetyltrimethylammonium bromide (CTAB) and ethylenediaminetetraacetic acid (EDTA) assisted hydrothermal route by using NaOH solution. Electron spin resonance (ESR/EPR) measurements of α-Fe2O4 nanoparticles have been performed by a conventional x-band spectrometer at room temperature. The comparison effect of nanoparticles prepared by using CTAB and EDTA in different α-doping on the structural and morphological properties have been investigated in detail. The effect of EDTA-assisted synthesis for α-Fe2O4 nanoparticles are refined, and thus the spectroscopic g-factor are detected by using ESR signals. These samples can be considered as great benefits for magnetic recording media, electromagnetic and drug delivery applications. Copyright © 2014 Elsevier B.V. All rights reserved.

  8. Studies on electronic spectrum and electron spin resonance of vanadium (IV) complexes with organophosphorus compounds and high molecular weight amines

    International Nuclear Information System (INIS)

    Sato, Taichi; Nakamura, Takato

    1981-01-01

    In the extraction of vanadium (IV) from aqueous solutions containing hydrochloric acid and/or a mixture of hydrochloric acid and lithium chloride by bis(2-ethylhexyl) hydrogenphosphate (DEHPA; HX), trioctylmethylammonium chloride (Aliquat-336), trioctylamine (TOA), trioctylphosphine oxide (TOPO) and tributyl phosphate (TBP), the complexes formed in the organic phases have been examined by spectrophotometry and electron spin resonance spectroscopy. It is found that in the extraction by DEHPA, the vanadium in the organic phase exists as the monomeric species, VO(X 2 H) 2 , or the polymeric one, (VOX 2 )sub(n), and that in the extractions by Aliquat-336, TOA, TOPO, and TBP, tetravalent vanadium complexes are stable in the organic phases extracted from a mixed solution of hydrochloric acid and lithium chloride, while complexes containing pentavalent vanadium and VOV 4+ ions are formed in the organic phases extracted from hydrochloric acid solutions. (author)

  9. Broadband electron spin resonance experiments using superconducting coplanar waveguides

    Energy Technology Data Exchange (ETDEWEB)

    Clauss, Conrad; Bogani, Lapo; Scheffler, Marc; Dressel, Martin [1. Physikalisches Institut, Universitaet Stuttgart (Germany); Bothner, Daniel; Koelle, Dieter; Kleiner, Reinhold [Physikalisches Institut - Experimentalphysik II and Center for Collective Quantum Phenomena in LISA+, Universitaet Tuebingen (Germany)

    2012-07-01

    In recent years superconducting coplanar devices operating at microwave/GHz frequencies are employed in more and more experimental studies. Here, we present electron spin resonance (ESR) experiments using a superconducting coplanar waveguide to provide the RF field to drive the spin flips. In contrast to conventional ESR studies this allows broadband frequency as well as magnetic field swept observation of the spin resonance. We show experimental data of the spin resonance of the organic radical NitPhoMe (2-(4'-methoxyphenyl)-4,4,5,5-tetra-methylimidazoline-1-oxyl-3-oxide) for frequencies in the range of 1 GHz to 40 GHz and corresponding magnetic fields up to 1.4 T (for g=2). In addition we show the temperature dependence of the ESR signals for temperatures up to 30 K, which is well above the critical temperature of the niobium superconductor.

  10. Electron spin resonance and electron spin echo modulation studies of Cu(II) ions in the aluminosilicate chabazite: A comparison of Cu(II) cation location and adsorbate interaction with isostructural silicoaluminophosphate-34

    International Nuclear Information System (INIS)

    Zamadics, M.; Kevan, L.

    1992-01-01

    This study focuses on Cu(II) ions exchanged in the aluminosilicate zeolite chabazite. The various Cu(II) species formed after dehydration, rehydration, and exposure to adsorbates are characterized by electron spin resonance and electron spin echo modulation spectroscopies. These results are interpreted in terms of Cu(II) ion location and adsorbate interaction. The results of this study are compared to the results found earlier for SAPO-34, chabazite's structural analog from the silicoaluminophosphate group. In a hydrated sample of chabazite the Cu(II) ions are found to be in a near octahedral environment coordinated to three nonequivalent water molecules and three framework oxygens. The most probable location of the Cu(II) ion in a hydrated sample is above the plane of the six-membered ring slightly displaced into the ellipsoidal cavity. A somewhat similar location and coordination is found for Cu(II) ions in H-SAPO-34. A feature common to both CuH-chabazite and CuH-SAPO-34 is the generation of two distinct Cu(II) species upon dehydration. It is found that Cu(II) cations in chabazite interact with the various adsorbate molecules in a similar manner as Cu(II) cation in H-chabazite and three molecules of ethanol and three propanol molecules. Only the Cu(II) ions located in the hexagonal rings after dehydration were found to complex with ethylene. The differences observed in the interaction of the Cu(II) in with water, propanol, and ehtylene between SAPO-34 and chabazite can be related to the differing cation densities of these two materials. 32 refs., 7 figs., 21 tabs

  11. Synthesis Properties and Electron Spin Resonance Properties of Titanic Materials

    International Nuclear Information System (INIS)

    Cho, Jung Min; Lee, Jun; Kim, Tak Hee; Sun, Min Ho; Jang, Young Bae; Cho, Sung June

    2009-01-01

    Titanic materials were synthesized by hydrothermal method of TiO 2 anatase in 10M LiOH, 10M NaOH, and 14M KOH at 130 deg. C for 30 hours. Alkaline media were removed from the synthesized products using 0.1N HCl aqueous solution. The as-prepared samples were characterized by scanning electron microscope, transmission electron microscope, X-ray diffraction, Brunauer-Emmett-Teller isotherm, and electron spin resonance. Different shapes of synthesized products were observed through the typical electron microscope and indicated that the formation of the different morphologies depends on the treatment conditions of highly alkaline media. Many micropores were observed in the cubic or octahedral type of TiO 2 samples through the typical electron microscope and Langmuir adsorption-desorption isotherm of liquid nitrogen at 77 deg. K. Electron spin resonance studies have also been carried out to verify the existence of paramagnetic sites such as oxygen vacancies on the titania samples. The effect of alkali metal ions on the morphologies and physicochemical properties of nanoscale titania are discussed.

  12. l-Tryptophan Radical Cation Electron Spin Resonance Studies: Connecting Solution-derived Hyperfine Coupling Constants with Protein Spectral Interpretations

    Science.gov (United States)

    Connor, Henry D.; Sturgeon, Bradley E.; Mottley, Carolyn; Sipe, Herbert J.; Mason, Ronald P.

    2009-01-01

    Fast-flow electron spin resonance (ESR) spectroscopy has been used to detect a free radical formed from the reaction of l-tryptophan with Ce4+ in an acidic aqueous environment. Computer simulations of the ESR spectra from l-tryptophan and several isotopically modified forms strongly support the conclusion that the l-tryptophan radical cation has been detected by ESR for the first time. The hyperfine coupling constants (HFCs) determined from the well-resolved isotropic ESR spectra support experimental and computational efforts to understand l-tryptophan's role in protein catalysis of oxidation-reduction processes. l-tryptophan HFCs facilitated the simulation of fast-flow ESR spectra of free radicals from two related compounds, tryptamine and 3-methylindole. Analysis of these three compounds' β-methylene hydrogen HFC data along with equivalent l-tyrosine data has led to a new computational method that can distinguish between these two amino acid free radicals in proteins without dependence on isotope labeling, electron nuclear double resonance or high-field ESR. This approach also produces geometric parameters (dihedral angles for the β-methylene hydrogens) which should facilitate protein site assignment of observed l-tryptophan radicals as has been done for l-tyrosine radicals. PMID:18433127

  13. Resonance fluorescence and electron spin in semiconductor quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Yong

    2009-11-18

    The work presented in this dissertation contains the first observation of spin-resolved resonance fluorescence from a single quantum dot and its application of direct measurement of electron spin dynamics. The Mollow triplet and the Mollow quintuplet, which are the hallmarks of resonance fluorescence, are presented as the non-spin-resolved and spin-resolved resonance fluorescence spectrum, respectively. The negligible laser background contribution, the near pure radiative broadened spectrum and the anti-bunching photon statistics imply the sideband photons are background-free and near transform-limited single photons. This demonstration is a promising step towards the heralded single photon generation and electron spin readout. Instead of resolving spectrum, an alternative spin-readout scheme by counting resonance fluorescence photons under moderate laser power is demonstrated. The measurements of n-shot time-resolved resonance fluorescence readout are carried out to reveal electron spin dynamics of the measurement induced back action and the spin relaxation. Hyperfine interaction and heavy-light hole mixing are identified as the relevant mechanisms for the back action and phonon-assistant spin-orbit interaction dominates the spin relaxation. After a detailed discussion on charge-spin configurations in coupled quantum dots system, the single-shot readout on electron spin are proposed. (orig.)

  14. Resonance fluorescence and electron spin in semiconductor quantum dots

    International Nuclear Information System (INIS)

    Zhao, Yong

    2009-01-01

    The work presented in this dissertation contains the first observation of spin-resolved resonance fluorescence from a single quantum dot and its application of direct measurement of electron spin dynamics. The Mollow triplet and the Mollow quintuplet, which are the hallmarks of resonance fluorescence, are presented as the non-spin-resolved and spin-resolved resonance fluorescence spectrum, respectively. The negligible laser background contribution, the near pure radiative broadened spectrum and the anti-bunching photon statistics imply the sideband photons are background-free and near transform-limited single photons. This demonstration is a promising step towards the heralded single photon generation and electron spin readout. Instead of resolving spectrum, an alternative spin-readout scheme by counting resonance fluorescence photons under moderate laser power is demonstrated. The measurements of n-shot time-resolved resonance fluorescence readout are carried out to reveal electron spin dynamics of the measurement induced back action and the spin relaxation. Hyperfine interaction and heavy-light hole mixing are identified as the relevant mechanisms for the back action and phonon-assistant spin-orbit interaction dominates the spin relaxation. After a detailed discussion on charge-spin configurations in coupled quantum dots system, the single-shot readout on electron spin are proposed. (orig.)

  15. Thermal behavior of organic free radicals in γ-ray irradiated pepper studied by electron spin resonance spectroscopy

    International Nuclear Information System (INIS)

    Ichii, Akane; Abe, Aika; Ukai, Mitsuko

    2003-01-01

    Using electron spin resonance (ESR) spectroscopy, we revealed heating effects on irradiated pepper. The representative ESR spectrum of the irradiated pepper is consisted of four components a sextet centered at g=2.0, a singlet at the same g-value, a singlet at g=4.0 and side peaks near g=2.0. The first one is attributable to a signal with hyperfine (hf) interactions of Mn 2+ (hf constant=7.4 mT). The second one is due to an organic free radical that is induced by the γ-ray irradiation. The third one may originated from Fe 3+ in the nonhem proteins. The fourth signal was found at the symmetric positions of the organic free radical, i.e., the second signal. Upon heating, the forth signals decreased monotonicaly. The ESR signal of the pepper heated for more than 10 min was essentially the same as that before the irradiation. On the other hand, the second signal increased and then leveled off at a constant value by further heating. This is indicative the occurrence of some biochemical reactions such as Maillard reaction during heating procedures. (author)

  16. Electron spin-resonance study on Ce{sup 3+} in BaLiF{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Yamaga, M. [Department of Electrical and Electronic Engineering, Faculty of Engineering, Gifu University, Gifu (Japan); Honda, M. [Faculty of Science, Naruto University of Education, Naruto (Japan); Shimamura, K.; Fukuda, T. [Institute for Materials Research, Tohoku University, Sendai (Japan); Yosida, T. [Nakanihon Automotive College, Kamo (Japan)

    2000-07-10

    Three distinct Ce{sup 3+} sites in BaLiF{sub 3} crystals estimated from the optical spectra are associated with configurations of Ce{sup 3+} accompanied by different charge compensators. This assignment is consistent with the electron spin-resonance (ESR) result that there are two tetragonal Ce{sup 3+} centres distorted along the [001] axis and two orthorhombic Ce{sup 3+} centres distorted along the [110] axis in the absence of the cubic centre. The configurations of the Ce{sup 3+} centres correspond to the substitution for Ba{sup 2+} ions along the [001] and [110] axes with Li{sup +} ions and the Ba{sup 2+}-ion vacancies along the [001] and [110] axes. The dominant component of the Ce{sup 3+} luminescence spectrum with the peak at {approx}320 nm and the large Stokes shift energy ({approx}8300 cm{sup -1}) is assigned as due to the substitution for a Ba{sup 2+} ion along the [001] axis with a Li{sup +} ion. As the ionic radius (0.74 A) of Li{sup +} is much smaller than that (1.60 A) of Ba{sup 2+}, the Li substitution produces more space, resulting in the large lattice relaxation in the 5d excited state of Ce{sup 3+}. (author)

  17. Electron spin resonance dating of fault gouge from Desamangalam

    Indian Academy of Sciences (India)

    The preliminary results from the electron spin resonance (ESR) dating on the quartz grains from the fault gouge indicate that the last major faulting in this site occurred 430 ± 43 ka ago. The experiments on different grain sizes of quartz from the gouge showed consistent decrease in age to a plateau of low values, indicating ...

  18. Identification of irradiated chicken meat using electron spin resonance spectroscopy

    International Nuclear Information System (INIS)

    Chawla, S.P.; Thomas, Paul

    2004-01-01

    Studies were carried out on detection of irradiation treatment in chicken using electron spin resonance (ESR) spectroscopy. The effect of gamma- irradiation treatment on radiation induced signal in different types of chicken namely, broiler, deshi and layers was studied. Irradiation treatment induced a characteristic ESR signal that was not detected in non-irradiated samples. The shape of the signal was not affected by type of the bone. The intensity of radiation induced ESR signal was affected by factors such as absorbed radiation dose, bone type irradiation temperature, post-irradiation storage, post-irradiation cooking and age of the bird. Deep-frying resulted in the formation of a symmetric signal that had a different shape and was weaker than the radiation induced signal. This technique can be effectively used to detect irradiation treatment in bone-in chicken meat even if stored and/or subjected to various traditional cooking procedures. (author)

  19. Magnetic and electron spin resonance studies of W doped CoFe2O4 polycrystalline materials

    Science.gov (United States)

    Singamaneni, S. R.; Martinez, L. M.; Swadipta, R.; Ramana, C. V.

    2018-05-01

    We report the magnetic and electron spin resonance (ESR) properties of W doped CoFe2O4 polycrystalline materials, prepared by standard solid-state reaction method. W was doped (0-15%) in CFO lattice on Fe site. Isothermal magnetization measurements reveal that the coercive field (Hc) (1300-2200 Oe) and saturation magnetization MS (35-82 emu/g) vary strongly as a function of W doping at all the temperatures (4-300 K) measured. We believe that a strong decrease in magnetic anisotropy in CFO after doping with W could cause a decrease in Hc. Up on doping CFO with W in place of Fe, the process transforms part of Fe3+ into Fe2+ due to the creation of more oxygen vacancies. This hinders the super-exchange interaction between Fe3+ and Fe2+, which causes a decrease in MS. Zero-field cooled (ZFC) and field cooled (FC, 1000 Oe) magnetization responses measured at 4 K on 1% W doped CFO show no indication of exchange bias, inferring that there are no other microscopic secondary magnetic phases (no segregation). This observation is corroborated by ESR (9.398 GHz) measurements collected as a function of temperature (10-150 K) and W doping (0-15%). We find that ESR spectra did not change after doping with W above 0.5%. However, ESR spectra collected from 0.5% W doped CFO sample showed a strong temperature dependence. We observed several ESR signals from 0.5% W doped CFO sample that could be due to phase separation.

  20. Magnetic and electron spin resonance studies of W doped CoFe2O4 polycrystalline materials

    Directory of Open Access Journals (Sweden)

    S. R. Singamaneni

    2018-05-01

    Full Text Available We report the magnetic and electron spin resonance (ESR properties of W doped CoFe2O4 polycrystalline materials, prepared by standard solid-state reaction method. W was doped (0-15% in CFO lattice on Fe site. Isothermal magnetization measurements reveal that the coercive field (Hc (1300-2200 Oe and saturation magnetization MS (35-82 emu/g vary strongly as a function of W doping at all the temperatures (4-300 K measured. We believe that a strong decrease in magnetic anisotropy in CFO after doping with W could cause a decrease in Hc. Up on doping CFO with W in place of Fe, the process transforms part of Fe3+ into Fe2+ due to the creation of more oxygen vacancies. This hinders the super-exchange interaction between Fe3+ and Fe2+, which causes a decrease in MS. Zero-field cooled (ZFC and field cooled (FC, 1000 Oe magnetization responses measured at 4 K on 1% W doped CFO show no indication of exchange bias, inferring that there are no other microscopic secondary magnetic phases (no segregation. This observation is corroborated by ESR (9.398 GHz measurements collected as a function of temperature (10-150 K and W doping (0-15%. We find that ESR spectra did not change after doping with W above 0.5%. However, ESR spectra collected from 0.5% W doped CFO sample showed a strong temperature dependence. We observed several ESR signals from 0.5% W doped CFO sample that could be due to phase separation.

  1. Unconventional spin dynamics in the honeycomb-lattice material α -RuCl3 : High-field electron spin resonance studies

    Science.gov (United States)

    Ponomaryov, A. N.; Schulze, E.; Wosnitza, J.; Lampen-Kelley, P.; Banerjee, A.; Yan, J.-Q.; Bridges, C. A.; Mandrus, D. G.; Nagler, S. E.; Kolezhuk, A. K.; Zvyagin, S. A.

    2017-12-01

    We present high-field electron spin resonance (ESR) studies of the honeycomb-lattice material α -RuCl3 , a prime candidate to exhibit Kitaev physics. Two modes of antiferromagnetic resonance were detected in the zigzag ordered phase, with magnetic field applied in the a b plane. A very rich excitation spectrum was observed in the field-induced quantum paramagnetic phase. The obtained data are compared with the results of recent numerical calculations, strongly suggesting a very unconventional multiparticle character of the spin dynamics in α -RuCl3 . The frequency-field diagram of the lowest-energy ESR mode is found consistent with the behavior of the field-induced energy gap, revealed by thermodynamic measurements.

  2. Proton location in metal hydrides using electron spin resonance

    International Nuclear Information System (INIS)

    Venturini, E.L.

    1979-01-01

    Electron spin resonance (ESR) of dilute paramagnetic ions establishes the site symmetry of these ions. In the case of metal hydrides the site symmetry is determined by the number and location of neighboring protons. Typical ESR spectra for trivalent erbium in scandium and yttrium hydrides are presented and analyzed, and this technique is shown to be a versatile microscopic probe of the location, net charge and occupation probability of nearby protons

  3. Electron spin resonance study of a-Cr2O3 and Cr2O3·nH2O quasi-spherical nanoparticles

    CSIR Research Space (South Africa)

    Khamlich, S

    2011-12-01

    Full Text Available The quasi-spherical nanoparticles of hydrated Cr2O3 · nH2O, and crystalline -Cr2O3, have been synthesized by reduction of the first row (3d) transition metal complex of K2Cr2O7. The temperaturedependence of electron spin resonance (ESR) spectrum...

  4. Probing quantum coherence in single-atom electron spin resonance

    Science.gov (United States)

    Willke, Philip; Paul, William; Natterer, Fabian D.; Yang, Kai; Bae, Yujeong; Choi, Taeyoung; Fernández-Rossier, Joaquin; Heinrich, Andreas J.; Lutz, Christoper P.

    2018-01-01

    Spin resonance of individual spin centers allows applications ranging from quantum information technology to atomic-scale magnetometry. To protect the quantum properties of a spin, control over its local environment, including energy relaxation and decoherence processes, is crucial. However, in most existing architectures, the environment remains fixed by the crystal structure and electrical contacts. Recently, spin-polarized scanning tunneling microscopy (STM), in combination with electron spin resonance (ESR), allowed the study of single adatoms and inter-atomic coupling with an unprecedented combination of spatial and energy resolution. We elucidate and control the interplay of an Fe single spin with its atomic-scale environment by precisely tuning the phase coherence time T2 using the STM tip as a variable electrode. We find that the decoherence rate is the sum of two main contributions. The first scales linearly with tunnel current and shows that, on average, every tunneling electron causes one dephasing event. The second, effective even without current, arises from thermally activated spin-flip processes of tip spins. Understanding these interactions allows us to maximize T2 and improve the energy resolution. It also allows us to maximize the amplitude of the ESR signal, which supports measurements even at elevated temperatures as high as 4 K. Thus, ESR-STM allows control of quantum coherence in individual, electrically accessible spins. PMID:29464211

  5. Observation of vacuum-enhanced electron spin resonance of optically levitated nanodiamonds

    Science.gov (United States)

    Li, Tongcang; Hoang, Thai; Ahn, Jonghoon; Bang, Jaehoon

    Electron spins of diamond nitrogen-vacancy (NV) centers are important quantum resources for nanoscale sensing and quantum information. Combining such NV spin systems with levitated optomechanical resonators will provide a hybrid quantum system for many novel applications. Here we optically levitate a nanodiamond and demonstrate electron spin control of its built-in NV centers in low vacuum. We observe that the strength of electron spin resonance (ESR) is enhanced when the air pressure is reduced. To better understand this novel system, we also investigate the effects of trap power and measure the absolute internal temperature of levitated nanodiamonds with ESR after calibration of the strain effect. Our results show that optical levitation of nanodiamonds in vacuum not only can improve the mechanical quality of its oscillation, but also enhance the ESR contrast, which pave the way towards a novel levitated spin-optomechanical system for studying macroscopic quantum mechanics. The results also indicate potential applications of NV centers in gas sensing.

  6. Detection of single electron spin resonance in a double quantum dota)

    Science.gov (United States)

    Koppens, F. H. L.; Buizert, C.; Vink, I. T.; Nowack, K. C.; Meunier, T.; Kouwenhoven, L. P.; Vandersypen, L. M. K.

    2007-04-01

    Spin-dependent transport measurements through a double quantum dot are a valuable tool for detecting both the coherent evolution of the spin state of a single electron, as well as the hybridization of two-electron spin states. In this article, we discuss a model that describes the transport cycle in this regime, including the effects of an oscillating magnetic field (causing electron spin resonance) and the effective nuclear fields on the spin states in the two dots. We numerically calculate the current flow due to the induced spin flips via electron spin resonance, and we study the detector efficiency for a range of parameters. The experimental data are compared with the model and we find a reasonable agreement.

  7. K-band single-chip electron spin resonance detector.

    Science.gov (United States)

    Anders, Jens; Angerhofer, Alexander; Boero, Giovanni

    2012-04-01

    We report on the design, fabrication, and characterization of an integrated detector for electron spin resonance spectroscopy operating at 27 GHz. The microsystem, consisting of an LC-oscillator and a frequency division module, is integrated onto a single silicon chip using a conventional complementary metal-oxide-semiconductor technology. The achieved room temperature spin sensitivity is about 10(8)spins/G Hz(1/2), with a sensitive volume of about (100 μm)(3). Operation at 77K is also demonstrated. Copyright © 2012 Elsevier Inc. All rights reserved.

  8. Electron spin resonance study of a La sub 0 sub . sub 7 Ca sub 0 sub . sub 3 MnO sub 3 single crystal

    CERN Document Server

    Joh, K W; Lee, C E; Hur, N H; Ri, H C

    2003-01-01

    Comprehensive measurements of electron spin resonance were carried out on a La sub 0 sub . sub 7 Ca sub 0 sub . sub 3 MnO sub 3 single crystal over a wide temperature range covering the ferromagnetic as well as the paramagnetic phases. Our analysis of the asymmetric lineshapes indicates that the phase segregation of good and poor conducting regions persists far above the ferromagnetic-paramagnetic phase transition temperature.

  9. Radiation dose measurement by electron spin resonance studies of tooth enamel in lime and non-lime consuming individuals from the Silchar region of northeast India

    International Nuclear Information System (INIS)

    Bhattacharjee, Deborshi; Zhumadilov, Kassym; Bhattacharyya, Joyeeta; Hoshi, Masaharu; Ivannikov, Alexander I.; Stepanenko, Valeriy F.; Tanaka, Kenichi; Endo, Satoru; Ohtaki, Megu; Toyoda, Shin

    2009-01-01

    Electron spin resonance (ESR) dosimetry of teeth is used extensively for dose estimation following exposure to radiation. The population inhabiting the northeast region of India is prone to different cancers of the head and neck, and their prevalence is several times the national average. The objective of this study was to determine the role of radiation in the causation of this high cancer incidence by performing ESR spectroscopic measurements of tooth samples collected from the general population living in and around the city of Silchar. Nineteen tooth samples were used, and the age of the patients was 13-60 years. The excess dose, determined by subtraction of the natural background dose from the dose absorbed by the enamel, was found to the extent of 123±43 mGy. However, the individual excess dose was found to be higher in subjects who consumed lime (5/6) than in non-lime-consuming subjects (2/13). It is not entirely clear if radiation is the cause of this excess cancer in this region of India. Therefore there is a need for wider studies including consideration of tobacco consumption as well as a larger number of samples for tooth enamel dosimetry. (author)

  10. Electron Spin Resonance Measurement with Microinductor on Chip

    Directory of Open Access Journals (Sweden)

    Akio Kitagawa

    2011-01-01

    Full Text Available The detection of radicals on a chip is demonstrated. The proposed method is based on electron spin resonance (ESR spectroscopy and the measurement of high-frequency impedance of the microinductor fabricated on the chip. The measurement was by using a frequency sweep of approximately 100 MHz. The ESR spectra of di(phenyl-(2,4,6-trinitrophenyliminoazanium (DPPH dropped on the microinductor which is fabricated with CMOS 350-nm technology were observed at room temperature. The volume of the DPPH ethanol solution was 2 μL, and the number of spins on the micro-inductor was estimated at about 1014. The sensitivity is not higher than that of the standard ESR spectrometers. However, the result indicates the feasibility of a near field radical sensor in which the microinductor as a probe head and ESR signal processing circuit are integrated.

  11. High-dose dosimetry using electron spin resonance (ESR) spectroscopy

    International Nuclear Information System (INIS)

    Kojima, Takuji; Tanaka, Ryuichi

    1992-01-01

    An electron spin resonance (ESR) dosimeter capable of measuring large doses of radiation in radiotherapy and radiation processing is outlined. In particular, an alanine/ESR dosimeter is discussed, focusing on the development of elements, the development of the ESR dosimetric system, the application of alanine/ESR dosimeter, and basic researches. Rod elements for gamma radiation and x radiation and film elements for electron beams are described in detail. The following recent applications of the alanine/ESR dosimeter are introduced: using as a transfer dosimeter, applying to various types of radiation, diagnosing the deterioration of radiological materials and equipments, and applying to ESR imaging. The future subjects to be solved in the alanine/ESR dosimetric system are referred to as follows: (1) improvement of highly accurate elements suitable for the measurement of various types of radiation, (2) establishment of sensitive calibration method of the ESR equipment itself, and (3) calibration and standardization of radiation doses. (K.N.) 65 refs

  12. Temperature dependent behavior of localized and delocalized electrons in nitrogen-doped 6H SiC crystals as studied by electron spin resonance

    Czech Academy of Sciences Publication Activity Database

    Savchenko, Dariia; Kalabukhova, E.; Shanina, B.; Cichoň, Stanislav; Honolka, Jan; Kiselov, V.; Mokhov, E.

    2016-01-01

    Roč. 119, č. 4 (2016), 1-7, č. článku 045701. ISSN 0021-8979 R&D Projects: GA ČR GP13-06697P; GA MŠk LO1409; GA MŠk(CZ) LM2011029 Grant - others:SAFMAT(XE) CZ.2.16/3.1.00/22132; AV ČR(CZ) Fellowship J. E. Purkyně Institutional support: RVO:68378271 Keywords : electron spin resonance * SiC * nitrogen donors * conduction electrons Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.068, year: 2016

  13. SU-E-I-78: Neuromelanin in the Subthalamic Nucleus of Patients with Parkinson's Disease: An Electron Spin Resonance Spectroscopy Study.

    Science.gov (United States)

    Gomez, J; Salmon, C Garrido; Filho, O Baffa; Santos, J Peixoto; Pitella, J

    2012-06-01

    Parkinson disease and related syndromes are associated directly with the concentrations of neuromelanin, iron and other heavy metals, and nowadays it is discussed the possible protective role of neuromelanin by the sequester redox active iron ions, reducing the formation of free hydroxyl radicals and therefore inactivating the iron ions that induce oxidative stress. The aim of this work is to study the concentration ratios between iron ions and neuromelanin in subthalamic nucleus of patients with Parkinson's disease (PD) using Electron Spin Resonance (ESR). Necropsy samples of subthalamic nucleus from eight human brains were studied: three non-affected by any neurodegenerative disease and five with Parkinson's disease. The samples were stored in formaldehyde and washed with a solution of 0.01 molar of ethylenediaminetetraacetic acid. ESR experiments were development in a JEOL FA-200 X-Band spectrometer at different temperatures between -170° C to room temperature. The relative concentrations of each species were estimated from the double integral values of the fitted spectra. For all samples, ESR spectra showed to be composed of three different signals following the Curie's law. One signal was attributed to high-spin ferric ions (g∼ 4.3) in rhomboedric symmetry, Cu(II) ions (close to g=2.0) and neuromelanin (g∼ 2.01). The ferric ions concentration ratio between patients and controls was 3.0±0.2. The same ratio for neuromelanine was 0.24±0.06. Our preliminary results indicated a significant increment of iron concentration in PD samples which agrees with previous histochemical and biochemical reports. This finding and the clear reduction of neuromelanin concentration in PD samples suggest the possible role of neuromelanin as iron ions storage. © 2012 American Association of Physicists in Medicine.

  14. An electron spin resonance study of radicals formed from tetrolic acid by radiolysis in a freon matrix

    International Nuclear Information System (INIS)

    Rhodes, C.J.

    1989-01-01

    In the present study, e.s.r. spectra have been observed following γ-irradiation of dilute frozen solutions of tetrolic acid, MeC≡CCO 2 H, in CFCl 3 at 77 K. A typical spectrum is shown which we interpret in terms of an isotropic quartet from the parent radical cation. MeC≡CCo 2 H +· , and an anisotropic triplet arising from the propargyl radical, ·CH 2 C≡CCO 2 H, formed by deprotonation of the parent cation. This appears to be the first example of an alkyne radical cation to be observed in a CFCl 3 matrix. (author)

  15. Depth profiles of pulmonary surfactant protein B in phosphatidylcholine bilayers, studied by fluorescence and electron spin resonance spectroscopy

    DEFF Research Database (Denmark)

    Cruz, A; Casals, C; Plasencia, I

    1998-01-01

    Pulmonary surfactant-associated protein B (SP-B) has been isolated from porcine lungs and reconstituted in bilayers of dipalmitoylphosphatidylcholine (DPPC) or egg yolk phosphatidylcholine (PC) to characterize the extent of insertion of the protein into phospholipid bilayers. The parameters...... for the interaction of SP-B with DPPC or PC using different reconstitution protocols have been estimated from the changes induced in the fluorescence emission spectrum of the single protein tryptophan. All the different reconstituted SP-B-phospholipid preparations studied had similar Kd values for the binding...... that there are significant differences in the extent of insertion of the protein, depending on the method of reconstitution. SP-B reconstituted from lipid/protein mixtures in organic solvents is inserted more deeply in PC or DPPC bilayers than the protein reconstituted by addition to preformed phospholipid vesicles...

  16. Radiation effects in the polycarbonate of bisphenol-A. Thermoluminescence electron spin resonance and charged particle track studies

    International Nuclear Information System (INIS)

    Edmonds, E.A.

    1978-09-01

    A detailed investigation is presented of the thermoluminescence observable above room temperature from the polycarbonate of bisphenol-A after its exposure to different radiations. A correlation study is described by which features of the complex thermoluminescence glow curve from a commercial grade of the polycarbonate of bisphenol-A are related to the etchability of charged particle damage trails and the radiogenic ESR signal. A model is presented whereby the etchability of charged particle damage trails is associated with chain scission caused by the high local dose of radiation in the vicinity of the trajectories of charged particles. Methods by which activation constants controlling the thermoluminescence glow curve can be evaluated are discussed and results are presented. It is concluded that glow peaks associated with the ESR signal or enhanced etchability are related to small-scale motions in the molecular matrix of the polycarbonate of bisphenol-A. These motions are thermally activated in accord with the simple Boltzmann relation usually incorporated into theories of thermoluminescence. Another component glow peak of the thermoluminescence glow curve is shown to be associated with the glass-rubber transition in the polycarbonate of bisphenol-A. Different features of the thermoluminescence glow curve can be related to relaxations of the polymer matrix and decomposition of the matrix. It is confirmed that the dominant bulk effect of radiation in the polycarbonate of bisphenol-A exposed to large doses of radiation is chain scission. (author)

  17. Radioprotective effects of dimethyl sulfoxide in golden hamster embryo cells exposed to gamma rays at 77 K. I. Radical formation as studied by electron spin resonance

    International Nuclear Information System (INIS)

    Miyazaki, T.; Hayakawa, Y.; Suzuki, K.; Suzuki, M.; Watanabe, M.

    1990-01-01

    Formation of free radicals in golden hamster embryo (GHE) cells in the frozen living state by gamma irradiation has been studied by electron spin resonance spectroscopy at 4.2 and 77 K. The relative yields of H atoms, OH radicals, and organic radicals trapped in the irradiated GHE cells are 12, 72, and 16%, respectively, of total radical yields. When dimethylsulfoxide (DMSO) is added to GHE cells at 77 K, a large quantity of CH2SOCH3 radicals (DMSO radicals) are formed after gamma irradiation. The yields of OH radicals are not affected by the addition of DMSO. When the GHE cell-DMSO mixtures are irradiated with gamma rays at 77 K and then warmed to 111 K, the OH radicals decay, whereas the DMSO radicals do not increase complementarily. Moreover, the decay rates of the OH radicals at 111 K do not depend upon the concentration of DMSO. Thus OH radicals do not react with DMSO during warming of the irradiated sample. When H atoms are produced by gamma irradiation of acid ice at 60 K, the decay rates of the H atoms at 77 K increase with increasing DMSO concentration, indicating that DMSO reacts with H atoms (CH3SOCH3 + H----.CH2SOCH3 + H2) at 77 K by quantum-mechanical tunneling. When the GHE cell-DMSO mixture is irradiated with gamma rays at 77 or 4.2 K in the dark, DMSO ions are produced in addition to DMSO radicals. Therefore it is concluded that DMSO does not scavenge OH radicals, but does capture H atoms, holes and/or electrons in the gamma-irradiated cells, resulting in the remarkable formation of DMSO radicals. This scavenger effect of DMSO may be related to the radioprotection of DMSO against cell killing

  18. A study on relation between nitroxyl radical reduction potency and X-ray irradiation on mouse lung using L-band electron spin resonance

    International Nuclear Information System (INIS)

    Taneike, Makoto; Sho, Keizen; Morita, Rikushi

    1999-01-01

    Changes in nitroxy radical reduction potency (''reduction potency''), caused by different doses and different number of fractions of X-ray irradiation were studied using a L-band electron spin resonance system on mouse lungs into which 4-hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl (hydroxy-TEMPO) was introduced through the trachea. The ''reduction potency'' lineally decreased as the irradiation dose increased from 1.0 to 5.0 Gy, but no further decrease was observed at higher doses of 7.5 and 10 Gy. The reduction potency'' dropped at 20 min after each irradiation, but it recovered to the control levels after 1 week in all 3 groups of single dose of 10 Gy, 3 fractions and 5 fractions in a similar manner. Although the levels of the ''reduction potency'' were kept high in the groups of fractionated irradiation through 1-4 weeks after irradiation, the levels dropped again in the single dose group at 1 week and the levels were kept significantly low until 4 weeks after irradiation. suggesting that the fractionation of X-ray irradiation would also be effective to prevent the deterioration of the ''reduction potency''. Pre-treatment with sufficient ascorbic acid inhibited the lowering effects of radiation on the ''reduction potency'' in a dose dependent manner. Furthermore the levels of the reduction potency'' ever elevated higher than those of controls with the large amount of ascorbic acid of 750 mg/kg or more, suggesting that the large amounts of ascorbic acid could prevent the adverse effects associated with radiation therapy for the lung malignancy. (author)

  19. Dose evaluation due to electron spin resonance method

    International Nuclear Information System (INIS)

    Nakajima, Toshiyuki

    1989-01-01

    Radiation dosimeter has been developed with free radical created in sucrose. Free radical was observed with using the electron spin resonance (ESR) equipment. The ESR absorption due to free radical in sucrose appeared at the magnetic field between the third and fourth ESR ones of Mn +2 standard sample. Sucrose as radiation dosimeter can linearly measure the dose from 5 x 10 -3 Gy to 10 5 Gy. If the new model of the ESR equipment is used and ESR observation is carried out at lower temperature such as liquid nitrogen or liquid helium temperature, the sucrose ESR dosimeter will be detectable about 5 x 10 -4 Gy or less. Fading of the free radicals in the irradiated sucrose was scarcely obtained about six months after irradiation and in the irradiated sucrose stored at 55deg C and 100deg C for one hour or more also scarcely observed. It is concluded from these radiation property that sucrose is useful for the accidental or emergency dosimeter for the inhabitants. (author)

  20. Mechanical detection of electron spin resonance beyond 1 THz

    International Nuclear Information System (INIS)

    Takahashi, Hideyuki; Ohmichi, Eiji; Ohta, Hitoshi

    2015-01-01

    We report the cantilever detection of electron spin resonance (ESR) in the terahertz (THz) region. This technique mechanically detects ESR as a change in magnetic torque that acts on the cantilever. The ESR absorption of a tiny single crystal of Co Tutton salt, Co(NH 4 ) 2 (SO 4 ) 2 ⋅6H 2 O, was observed in frequencies of up to 1.1 THz using a backward travelling wave oscillator as a THz-wave source. This is the highest frequency of mechanical detection of ESR till date. The spectral resolution was evaluated with the ratio of the peak separation to the sum of the half-width at half maximum of two absorption peaks. The highest resolution value of 8.59 ± 0.53 was achieved at 685 GHz, while 2.47 ± 0.01 at 80 GHz. This technique will not only broaden the scope of ESR spectroscopy application but also lead to high-spectral-resolution ESR imaging

  1. Electron spin resonance probed competing states in NiMnInSi Heusler alloy

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Y.S. [Center for Condensed Matter Sciences, National Taiwan University, Taipei 10617, Taiwan (China); Lin, J.G., E-mail: jglin@ntu.edu.tw [Center for Condensed Matter Sciences, National Taiwan University, Taipei 10617, Taiwan (China); Titov, I.S.; Granovsky, A.B. [Faculty of Physics, Lomonosov Moscow State University, Vorob' evy Gory, 11999l Moscow (Russian Federation)

    2016-06-01

    Shape memory Heusler alloy Ni{sub 50}Mn{sub 35}In{sub 12}Si{sub 3} is investigated with electron spin resonance (ESR) technique in a temperature range of 200–300 K. ESR is a dynamic probe allowing us to separate the responses from various magnetic phases, thus to study the complex phase transitions. The sample shows three transition temperatures: T{sub c}{sup A} (271 K), T{sub M} (247 K) and T{sub c}{sup M} (212 K), where T{sub c}{sup A} is the Curie temperature of austenitic phase, T{sub M} and T{sub c}{sup M} are the temperatures of magnetostructural martensitic transition and the Curie temperature of martensitic phase, respectively. Furthermore, ESR data reveals the coexistence of two magnetic modes in whole temperature range of 200–300 K. Particularly in martensitic phase, two magnetic modes are attributed to two different kinds of lattice deformation, the slip and twinning deformations. - Highlights: • Electron spin resonance study on magnetocaloric Heusler alloy within 200–300 K. • Magnetic phase separation below and above the structural transition temperature. • Phase competing is in association with different types of lattice distortions. • Electron spin resonance results are complementary to the magnetization data.

  2. Magnetic, electrical transport and electron spin resonance studies of Fe-doped manganite LaMn0.7Fe0.3O3+δ

    International Nuclear Information System (INIS)

    Liu, X.J.; Li, Z.Q.; Yu, A.; Liu, M.L.; Li, W.R.; Li, B.L.; Wu, P.; Bai, H.L.; Jiang, E.Y.

    2007-01-01

    We have investigated the magnetic, electrical transport and electron spin resonance (ESR) properties of polycrystalline Fe-doped manganite LaMn 0.7 Fe 0.3 O 3+ δ prepared by sol-gel method. A typical cluster-glass feature is presented by DC magnetization and AC susceptibility measurements and a sharp but shallow memory effect was observed. Symmetrical Lorentzian lines of the Mn/Fe spectra were detected above 120 K, where the sample is a paramagnetic (PM) insulator. When the temperature decreases from 120 K, magnetic clusters contributed from ferromagnetic (FM) interaction between Mn 3+ and Mn 3+ /Fe 3+ ions develop and coexist with PM phase. At lower temperature, these FM clusters compete with antiferromagnetic (AFM) ones between Fe 3+ ions, which are associated with a distinct field-cooled (FC) effect in characteristic of cluster-glass state

  3. Ferromagnetic resonance characterization of nano-FePt by electron spin resonance

    CSIR Research Space (South Africa)

    Nkosi, SS

    2013-01-01

    Full Text Available Electron spin resonance (ESR) measurements at room temperature and X-band microwave frequency were performed on highly crystalline FePt system thin films. Fairly high DC static magnetic field absorption of about 300 mT was observed in these films...

  4. Electron spin resonance and optical studies on the radiolysis of carbon tetrachloride. II. Structure and reaction of CClṡ-4 radical anion in tetramethylsilane low-temperature solids

    Science.gov (United States)

    Muto, Hachizo; Nunome, Keichi

    1991-04-01

    An electron spin resonance (ESR) and optical study of carbon tetrachloride radical anion has been made to provide for a better understanding of the radiolysis of CCl4, following CClṡ+4 cation previously studied. It was found that the anion was metastably trapped in tetramethylsilane (TMS) matrices γ irradiated at 4 or 77 K. The g tensor and the hyperfine coupling tensors of all atoms of the radical were determined from ESR spectral simulation by using 12 CCl4 and the 13C enriched compound: g∥=2.004-5, g1=2.015,(A∥,A⊥) =(24.3,18.3) mT for 13C, (0.9, 0.2) mT for one 35Cl atom, and (A1,A2=A3)=(1.98,0.45) mT for the other three equivalent 35Cl atoms. From these parameters and a consideration on the g anisotropy combined with the optical data, the anion was found to have a predissociating molecular structure (CCl3ṡṡṡCl) ˙- with C3v symmetry, where the unpaired electron occupies A*1γ antibonding orbital. The carbon atom has a large spin density and near sp3 hybridization: ρp=0.62, ρs=0.18, ρp/ρs=3.4, and three Cl atoms and the other Cl atom have the spin densities ρp=0.10 and ρp=0.05, respectively. The species had two optical absorptions at λmax=265 and 370 nm which were assigned to the Eγ-A*1γ and A1γ-A*1γ electronic transitions, respectively. The anion converted to CCl ṡ3 radical by warming to ˜150 K in the TMS matrix. The present results have given unequivocal ESR and optical spectroscopic evidence and support for the assignment of the 370 nm band reported in the radiolyses of organic solutions containing CCl4.

  5. Detection by electron spin resonance of young cock irradiated with 60 Co

    International Nuclear Information System (INIS)

    Villavicencio, A.L.C.H.; Duarte, C.L.; Mastro, N.L. del.

    1992-01-01

    The Electron Spin Resonance was used to measuring the production of free radicals induced by ionizing radiation in young cock bones on doses of 3,5 and 7,0 K Gy. It was studied the design decay by 30 days after the irradiation in environment temperature. The results show that the measures by resonance in bones can be used for detecting if the flesh sample that has bone was irradiated or not. The measures show the possibility of use post-irradiation dosimetry in food producst. (C.G.C.)

  6. Radiosterilization dosimetry by electron-spin resonance spectroscopy. Cefotetan

    International Nuclear Information System (INIS)

    Basly, J.P.; Longy, I.; Bernard, M.

    1998-01-01

    As an alternative to heat and gas exposure sterilization, ionizing radiation is gaining interest as a sterilization process for medicinal products. Nevertheless, essentially for economic profit, unauthorized and uncontrolled use of radiation processes may be expected. In this context, it is necessary to find methods of distinguishing between irradiated and nonirradiated pharmaceuticals. In the absence of suitable detection methods, our attention was focused on electron-spin resonance (ESR) spectrometry. A third generation cephalosporin, cefotetan, was chosen as a model; this antibiotic is a potential candidate for radiation treatment due to its thermosensitivity. While the ESR spectra of a nonirradiated sample presents no signal, a nonsymmetrical signal, dependent on the irradiation dose, is found in irradiated samples. The number of free radicals was estimated by comparing the second integral from radiosterilized samples and a diphenylpicryl hydrazyl reference. Estimation of the number of free radicals gives 7x10 17 radicals g -1 at 20kGy (1.1x10 16 radicals in 15mg). From this result, the G-value (number of radicals (100eV) -1 ) could be estimated as 0.6. Decay of radicals upon storage were modeled using a bi-exponential function. The limit of detection of free radicals after irradiation at 25kGy is up to two years. This result agrees with those obtained on other cephalosporins. Aside from qualitative detection, ESR spectrometry can be used for dose estimation. Linear regression is applicable for doses lower than 20kGy. Since the radiation dose selected must always be based upon the bioburden of the products and the degree of sterility required (EN 552 and ANSI/AAMI/ISO 11137), 25kGy could no longer be accepted as a 'routine' dose for sterilizing a pharmaceutical. Doses in the 5-20kGy range could be investigated and linear regression appeared to be the least expensive route to follow. The best results for the integration of the curves were obtained with

  7. The radical cations of sulphur (S8sup(.+)) and tetrasulphur tetranitride (S4N4sup(.+)): a radiation-electron spin resonance study

    International Nuclear Information System (INIS)

    Chandra, Harish; Ramakrishna Rao, D.N.; Symons, M.C.R.

    1987-01-01

    Exposure of dilute solutions of S 8 and S 4 N 4 in trichlorofluoromethane to 60 Co γ-rays at 77 K gave the corresponding radical cations. Enrichment (99%) with 33 S gave greatly broadened electron spin resonance x and y features, with A( 33 S) approx. = + - 4 G, where A is the first formed species from sulfur. The z features showed a clear central line flanked by others with Asub(z) approx. = 28 G. The results suggest the presence of two equally coupled sulphur atoms. On annealing, species (A) changes irreversibly into species (B),possibly, S 8 radical + in a relaxed form in which two opposite atoms have formed a weak three-electron bond. A clear spectrum was produced from S 4 N 4 which showed little g-value variation and no evidence for 14 N splitting. It is concluded that the S 4 N 4 radical + cation has a relatively isolated semi-occupied molecular orbital, with low spin density on nitrogen. (author)

  8. Retrospective Dosimetry: Dose Analysis From Tooth Enamel Using Electron Spin Resonance (ESR)

    International Nuclear Information System (INIS)

    Mohd Rodzi Ali; Rahimah Abdul Rahim; Noraisyah Yusof; Syed Asraf Fahlawi Wafa Syed Mohd Ghazi; Juliana Mahamad Napiah; Yahaya Talib; Rehir Dahalan

    2014-01-01

    The radiation dose should be accurately measured in order to relate its effect to the cells. The assessment of dose usually performed using biological dosimetry techniques. However, the reduction of lymphocytes (white blood cells) after the time period results in inaccuracy of dose measurement. An alternative method used is the application of Electron Spin Resonance (ESR) using tooth enamel. In this study, tooth enamels were evaluated and used to measure the individual absorbed dose from the background. The basic tooth features that would affect dose measurement were discussed. The results show this technique is capable and effective for retrospective dose measurement and useful for the study of radiation effect to human. (author)

  9. Sensitivity and spatial resolution for electron-spin-resonance detection by magnetic resonance force microscopy

    International Nuclear Information System (INIS)

    Zhang, Z.; Roukes, M.L.; Hammel, P.C.

    1996-01-01

    The signal intensity of electron spin resonance in magnetic resonance force microscopy (MRFM) experiments employing periodic saturation of the electron spin magnetization is determined by four parameters: the rf field H 1 , the modulation level of the bias field H m , the spin relaxation time τ 1 , and the magnetic size R(∂H/∂z) of the sample. Calculations of the MRFM spectra obtained from a 2,2-diphenyl-1-picrylhydrazyl particle have been performed for various conditions. The results are compared with experimental data and excellent agreement is found. The systematic variation of the signal intensity as a function of H 1 and H m provides a powerful tool to characterize the MRFM apparatus. copyright 1996 American Institute of Physics

  10. Radiation dosimetry for residents of the Chernobyl region: a comparison of cytogenetic and electron spin resonance methods

    Energy Technology Data Exchange (ETDEWEB)

    Serezhenkov, V A; Mordvintcev, P I; Vanin, A F; Voevodskaya, N V [AN SSSR, Moscow (Russian Federation). Inst. Fizicheskoj Khimii; Domracheva, E V; Kulikov, S M; Kuznetsov, S A; Schklovsky-Kordi, N E; Vorobiev, A I [National Center for Haematology, Moscow (Russian Federation); Klevezal, G A; Sukhovskaya, L I [Russian Academy of Science, Moscow (Russian Federation). Inst. of Developmental Biology

    1992-01-01

    Persons from the Gomel region of Byelorussia who were irradiated by the Chernobyl reactor accident have been studied. Estimations of their radiation doses using electron spin resonance spectrometry of dental enamel showed good agreement with dosimetry by chromosomal analysis of blood lymphocytes. (author).

  11. Electron Spin Resonance (ESR) and Thermoluminescence (TL) studies of stalagmitic floors of the Caune de de L'Arago at Tautavel (France)

    International Nuclear Information System (INIS)

    Poupeau, G.; Teles, M.M.; Rossi, A.; Zuleta, E.; Yokoyama, Y.

    1984-01-01

    The geological radiation dose to the stalagmites of various stratigraphic levels of the Caune de L'Arago at Tautavel has been measured by Thermoluminescence (TL) and Electron Spin Resonance (ESR). In all samples the TL natural spectrum a well developped 280 0 C peak and a subordinate 350 0 C peak, while the ESR line spectrum may present the h 1 , h 2 and h 3 radiative lines of Yokoyama et al.) or only h 2 . All TL peaks and ESR lines do increase with the laboratory applied radiation (β or γ) doses. The activated h 2 line is visibly unstable in laboratory conditions as well as apparently the h 3 line in one sample. Within the experimental precision, the geological doses determined from the 280C peak and h 3 line on one band and the 350 0 C peak and h 1 line (after thermal treatment of the later, see Yokoyama et al. on the other hand are identical. When the 280C natural peak is visibly affected by natural fading as shown by the plateau test, so is h 3 , and the geological doses of the 280 0 C-h 3 peaks are lowered by the same factor as compared to those of the 350 0 C-h 1 peaks. Annealing experiments show that the relationships between the TL and ESR peaks may be difficult to analyse in some samples due to the possible occurence of non radiative components in some ESR lines. Such components appear clearly at temperatures above approx. 180-200 0 C and might possibly be present below. This may have important implications for the selection of samples to be dated by ESR. (Author) [pt

  12. Study by electron spin resonance of the free radicals created under irradiation in glycine; Etude par la technique de resonance paramagnetique electronique des radicaux crees sous irradiation dans la glycine

    Energy Technology Data Exchange (ETDEWEB)

    Thomet, P; Rassat, A; Servoz-Gavin, P; Choudens, H de [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

    1967-07-01

    The free radicals created by different radiations in glycine are measured by electron spin resonance and their number is evaluated in function of the absorbed dose. This number decreases when the LET of the radiations increases ; in other words,high LET radiations gives less radiochemical effects; in contrary with the fact that high LET radiations creates more damage in biological materials. The decreasing with time of the number of free radicals and the speed of this decrease is a function of temperature; by the study of the kinetics of this decrease, an attempt has been made to prove the presence of three radicals. (authors) [French] Les radicaux crees par divers rayonnements dans la glycine sont detectes par resonance paramagnetique electronique et leur nombre est evalue en fonction de la dose. Ce nombre varie dans le sens inverse du T.E.L moyen, c'est-a-dire que les rayonnements de T.E.L eleves donnent des effets radiochimiques plus petits alors que les effets radiobiologiques sont importants avec des T.E.L eleves. La decroissance dans le temps du nombre de radicaux est observee et la vitesse de diminution des radicaux est liee a la temperature. Etudiant la cinetique de recombinaison, on peut faire l'hypothese de l'existence de 3 radicaux. (auteurs)

  13. Synthesis Properties and Electron Spin Resonance Properties of Titanic Materials (abstract)

    Science.gov (United States)

    Cho, Jung Min; Lee, Jun; Kim, Tak Hee; Sun, Min Ho; Jang, Young Bae; Cho, Sung June

    2009-04-01

    Titanic materials were synthesized by hydrothermal method of TiO2 anatase in 10M LiOH, 10M NaOH, and 14M KOH at 130° C for 30 hours. Alkaline media were removed from the synthesized products using 0.1N HCl aqueous solution. The as-prepared samples were characterized by scanning electron microscope, transmission electron microscope, X-ray diffraction, Brunauer-Emmett-Teller isotherm, and electron spin resonance. Different shapes of synthesized products were observed through the typical electron microscope and indicated that the formation of the different morphologies depends on the treatment conditions of highly alkaline media. Many micropores were observed in the cubic or octahedral type of TiO2 samples through the typical electron microscope and Langmuir adsorption-desorption isotherm of liquid nitrogen at 77° K. Electron spin resonance studies have also been carried out to verify the existence of paramagnetic sites such as oxygen vacancies on the titania samples. The effect of alkali metal ions on the morphologies and physicochemical properties of nanoscale titania are discussed.

  14. An efficient digital phase sensitive detector for use in electron spin resonance spectroscopy

    International Nuclear Information System (INIS)

    Vistnes, A.I; Wormald, D.I.; Isachsen, S.

    1983-10-01

    A digital sensitive detector for a modified Bruker electron spin resonance spectrometer, equipped with an Aspect 2000 minicomputer, is described. Magnetic field modulation is derived from a clock in the computer, which makes it possible to perform the data acquisition fully synchronously with the modulation. The resulting high phase accuracy makes it possible to compress the data to a single modulation period before the Fourier transformation. Both the in-phase and the phase-quadrature signals (of the first or second harmonic) are recorded simultaneously. The system makes the data processing, including the Fourier transformation, approximately 1000 times faster than previously reported digital phase sensitive detector systems for electron spin resonance spectrometers

  15. Electron spin resonance and E.N.D.O.R. double resonance study of free radicals produced by gamma irradiation of imidazole single crystals

    International Nuclear Information System (INIS)

    Lamotte, B.

    1970-01-01

    Gamma irradiation of imidazole single crystals at 300 deg. K gives two radicals. Identification and detailed studies of their electronic and geometric structure have been made by ESR and ENDOR techniques. A study of the hydrogen bonded protons hyperfine tensor is made and let us conclude to the inexistence of movement and tunneling of these protons. The principal low temperature radical, produced by gamma irradiation at 77 deg. K has been also studied by ESR and a model has been proposed. (author) [fr

  16. Application of electron spin resonance for evaluation of the level of ...

    Indian Academy of Sciences (India)

    Abstract. In order to identify and quantify free radicals in the tissues of patients with normal physiological and pathological states of births, we developed a method to evaluate the amount of free radicals in myometrium of subplacental area and from body of uterus, using electron spin resonance spectroscopy. Analysis of the ...

  17. A point of view about identification of irradiated foods by electron spin resonance

    International Nuclear Information System (INIS)

    Saint-Lebe, L.; Raffi, J.

    1986-11-01

    Principles and conditions required for using electron spin resonance (ESR) in identifying irradiated foods are first put forth. After a literature review, examples of irradiated cereals and French prunes are described in order to derive general conclusions concerning the future of ESR in this field

  18. Electron spin resonance from NV centers in diamonds levitating in an ion trap

    International Nuclear Information System (INIS)

    Delord, T; Nicolas, L; Schwab, L; Hétet, G

    2017-01-01

    We report observations of the electron spin resonance (ESR) of nitrogen vacancy centers in diamonds that are levitating in an ion trap. Using a needle Paul trap operating under ambient conditions, we demonstrate efficient microwave driving of the electronic spin and show that the spin properties of deposited diamond particles measured by the ESR are retained in the Paul trap. We also exploit the ESR signal to show angle stability of single trapped mono-crystals, a necessary step towards spin-controlled levitating macroscopic objects. (paper)

  19. The temperature dependence of quantum spin pumping generated using electron spin resonance with three-magnon splittings

    International Nuclear Information System (INIS)

    Nakata, Kouki

    2013-01-01

    On the basis of the Schwinger–Keldysh formalism, we have closely investigated the temperature dependence of quantum spin pumping generated using electron spin resonance. We have clarified that three-magnon splittings excite non-zero modes of magnons and characterize the temperature dependence of quantum spin pumping generated using electron spin resonance. (paper)

  20. Characterization of functional LB films using electron spin resonance spectroscopy

    International Nuclear Information System (INIS)

    Kuroda, Shin-ichi

    1995-01-01

    The role of ESR spectroscopy in the characterization of functional LB films is discussed. Unpaired electrons in LB films are associated with isolated radical molecules produced by charge transfer, paramagnetic metallic ions such as Cu 2+ , strongly interacting spins in the mixed valence states in charge-transfer salts, and so on. These spins often manifest the functions of materials. They can also act as microscopic probes in the ESR analysis devoted for the elucidation of characteristic properties of LB films. In structural studies, ESR is of particular importance in the analysis of molecular orientation of LB films. ESR can unambiguously determine the orientation of molecules through g-value anisotropy: different g value, different resonance field. Two types of new control methods of molecular orientation in LB films originated from the ESR analysis: study of in-plane orientation in dye LB films which led to the discovery of flow-orientation effect, and observation of drastic change of orientation of Cu-porphyrin in LB films using the trigger molecule, n-hexatriacontane. In the studies of electronic properties, hyperfine interactions between electron and nuclear spins provide information about molecular orbitals and local structures. Stable isotopes have been successfully applied to the stable radicals in merocyanine LB films to identify hyperfine couplings. In conducting LB films composed of charge-transfer salts, quasi-one-dimensional antiferromagnetism in semiconducting films and spin resonance of conduction electrons in metallic films are observed. Results provide microscopic evidence for the development of columnar structures of constituent molecules. Development of new functional LB films may provide more cases where ESR spectroscopy will clarify the nature of such films. (author)

  1. Electron spin resonance study of electron localization and dynamics in metal-molten salt solutions: comparison of M-MX and Ln-LnX sub 3 melts (M alkali metal, Ln = rare earth metal, X = halogen)

    CERN Document Server

    Terakado, O; Freyland, W

    2003-01-01

    We have studied the electron spin resonance (ESR) spectra in liquid K-KCl and M-(NaCl/KCl) sub e sub u sub t mixtures at different concentrations in salt-rich melts approaching the metal-nonmetal transition region. In both systems F-centre-like characteristics are found. Strongly exchange narrowed signals clearly indicate that fast electron exchange occurs on the picosecond timescale. In contrast, the ESR spectra of a (NdCl sub 2)(NdCl sub 3)-(LiCl/KCl) sub e sub u sub t melt are characterized by a large line width of the order of 10 sup 2 mT which decreases with increasing temperature. In this case, the g-factor and correlation time are consistent with the model of intervalence charge transfer, which is supported by recent conductivity and optical measurements. The different transport mechanisms will be discussed.

  2. Identification of irradiated peppers by electron spin resonance, thermoluminescence and viscosity

    International Nuclear Information System (INIS)

    Polonia, I.; Esteves, M.P.; Andrade, M.E.; Laboratorio Nacional de Engenharia e Tecnologia Industrial, Sacavem; Empis, J.

    1995-01-01

    White and black pepper purchased in local retailers were analysed by electron spin resonance (ESR), thermoluminescence (TL) and viscosimetry (VISC) in order to establish a viable method for identifying possibly irradiated peppers. Samples studied were non irradiated or irradiated in a cobalt-60 plant with the absorbed doses of 3, 5, 7 and 10 kGy. Confirming the data found in the literature TL was revealed by our results the best method to identify irradiated peppers. Nevertheless, the dose received by the samples could not be estimated. The ESR signal of irradiated peppers is similar to the spectrum of cellulose radical but very short lived at ambient temperature. The study on the alteration of viscosity of heat-treated alkaline pepper suspensions indicate that VISC is a very promising method for detection of irradiated peppers. (Author)

  3. Electron spin resonance and quantum critical phenomena in VOx multiwall nanotubes

    International Nuclear Information System (INIS)

    Demishev, S.V.; Chernobrovkin, A.L.; Glushkov, V.V.; Samarin, N.A.; Sluchanko, N.E.; Semeno, A.V.; Goodilin, E.A.; Grigorieva, A.V.; Tretyakov, Yu.D.

    2008-01-01

    Basing on the high frequency (60 GHz) electron spin resonance study of the VO x multiwall nanotubes (VO x -NTs) carried out in the temperature range 4.2-200 K we report: (i) the first direct experimental evidence of the presence of the antiferromagnetic dimers in VO x -NTs and (ii) the observation of an anomalous low temperature growth of the magnetic susceptibility for quasi-free spins, which obey the power law χ(T)∝1/T α with the exponent α∼0.6 in a wide temperature range 4.2-50 K. We argue that the observed departures from the Curie-Weiss behaviour manifest the onset of the quantum critical regime and formation of the Griffiths phase as a magnetic ground state of these spin species. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  4. DETECTION OF SOME IRRADIATED NUTS BY ELECTRON SPIN RESONANCE (ESR) TECHNIQUE

    International Nuclear Information System (INIS)

    KHALLAF, M.F.; YASIN, N.M.N.; EL-NASHABY, F.M.; ALI, H.G.M.; EL-SHIEMY, S.M.

    2008-01-01

    The present investigation was carried out to establish the electron spin resonance (ESR) detection method for identifying irradiated nuts (almond and pistachio). Samples were irradiated with 2, 4 and 6 kGy and stored at room temperature (25± 2 0 C) for six months to study the possibility of detecting its previous irradiation treatments by ESR spectroscopy. Analysis was carried out just after irradiation treatment and during ambient storage period. The ESR signal intensities of irradiated samples were markedly increased correspondingly with irradiation dose as a result of free radicals generated by gamma irradiation so, all irradiated samples under investigation could be differentiated from non-irradiated ones immediately after irradiation treatment. The decay in radicals responsible of ESR signals showed the identification of irradiated almond (shell or edible part) and pistachio (edible part) was impossible after six months of ambient storage

  5. DETECTION OF SOME IRRADIATED NUTS BY ELECTRON SPIN RESONANCE (ESR) TECHNIQUE

    Energy Technology Data Exchange (ETDEWEB)

    KHALLAF, M F; YASIN, N M.N. [Food Science Dept., Faculty of Agriculture, Ain Shams University, Cairo (Egypt); EL-NASHABY, F M; ALI, H G.M.; EL-SHIEMY, S M [Nuclear Research Centre, Atomic Energy Authority, Cairo (Egypt)

    2008-07-01

    The present investigation was carried out to establish the electron spin resonance (ESR) detection method for identifying irradiated nuts (almond and pistachio). Samples were irradiated with 2, 4 and 6 kGy and stored at room temperature (25{+-} 2{sup 0}C) for six months to study the possibility of detecting its previous irradiation treatments by ESR spectroscopy. Analysis was carried out just after irradiation treatment and during ambient storage period. The ESR signal intensities of irradiated samples were markedly increased correspondingly with irradiation dose as a result of free radicals generated by gamma irradiation so, all irradiated samples under investigation could be differentiated from non-irradiated ones immediately after irradiation treatment. The decay in radicals responsible of ESR signals showed the identification of irradiated almond (shell or edible part) and pistachio (edible part) was impossible after six months of ambient storage.

  6. Free radical scavenging activities of yellow gentian (Gentiana lutea L.) measured by electron spin resonance.

    Science.gov (United States)

    Kusar, A; Zupancic, A; Sentjurc, M; Baricevic, D

    2006-10-01

    Yellow gentian (Gentiana lutea L.) is a herbal species with a long-term use in traditional medicine due to its digestive and stomachic properties. This paper presents an investigation of the free radical scavenging activity of methanolic extracts of yellow gentian leaves and roots in two different systems using electron spin resonance (ESR) spectrometry. Assays were based on the stable free radical 1,1-diphenyl-2-picrylhydrazyl (DPPH) and the superoxide radicals (O2*-) generated by the xanthine/xanthine oxidase (X/XO) system. The results of gentian methanolic extracts were compared with the antioxidant capacity of synthetic antioxidant butylated hydroxyanisole (BHA). This study proves that yellow gentian leaves and roots exhibit considerable antioxidant properties, expressed either by their capability to scavenge DPPH or superoxide radicals.

  7. Electron spin resonance dating of teeth from Western Brazilian megafauna - preliminary results

    Energy Technology Data Exchange (ETDEWEB)

    Kinoshita, Angela, E-mail: angela.kinoshita@usc.br [Departamento de Fisica, FFCLRP, Universidade de Sao Paulo, 14040-901 Ribeirao Preto-SP (Brazil); Universidade Sagrado Coracao, Rua Irma Arminda 10-50, 17011-160 Bauru - Sao Paulo (Brazil); Jose, Flavio A. [Departamento de Fisica, FFCLRP, Universidade de Sao Paulo, 14040-901 Ribeirao Preto-SP (Brazil); Sundaram, Dharani; Paixao, Jesus da S.; Soares, Isabella R.M. [Universidade Federal de Mato Grosso, Departamento de Geologia Geral, 78090-000 Cuiaba-MT (Brazil); Figueiredo, Ana Maria [Instituto de Pesquisas Energeticas e Nucleares (IPEN), 05422-970 Sao Paulo-SP (Brazil); Baffa, Oswaldo [Departamento de Fisica, FFCLRP, Universidade de Sao Paulo, 14040-901 Ribeirao Preto-SP (Brazil)

    2011-09-15

    Electron Spin Resonance (ESR) was applied to determine ages of Haplomastodon teeth from Western Brazilian Megafauna. The Equivalent Doses (D{sub e}) of (1.3 {+-} 0.2)kGy, (800 {+-} 100)Gy and (140 {+-} 20)Gy were found and the software ROSY ESR dating was employed to convert D{sub e} in age, using isotope concentrations determined by neutron activation analysis (NAA) and other information, resulting in (500 {+-} 100)ka, (320 {+-} 50) and (90 {+-} 10)ka considering the Combination Uptake (CU) model for Uranium uptake, set as an Early Uptake (EU) for dentine and Linear Uptake (LU) for enamel. There are scarce reports about Pleistocene Megafauna in this area. This paper presents the first dating of megafauna tooth and this study could contribute to improve the knowledge about the paleoclimate and paleoenvironment of this region and prompt more investigations in this area.

  8. Analysis of electron spin resonance spectra of irradiated gingers: Organic radical components derived from carbohydrates

    International Nuclear Information System (INIS)

    Yamaoki, Rumi; Kimura, Shojiro; Ohta, Masatoshi

    2010-01-01

    Electron spin resonance (ESR) spectral characterizations of gingers irradiated with electron beam were studied. Complex asymmetrical spectra (near g=2.005) with major spectral components (line width=2.4 mT) and minor signals (at 6 mT apart) were observed in irradiated gingers. The spectral intensity decreased considerably 30 days after irradiation, and continued to decrease steadily thereafter. The spectra simulated on the basis of characteristics of free radical components derived from carbohydrates in gingers are in good agreement with the observed spectra. Analysis showed that shortly after irradiation the major radical components of gingers were composed of radical species derived from amylose and cellulose, and the amylose radicals subsequently decreased considerably. At 30 days after irradiation, the major radical components of gingers were composed of radical species derived from cellulose, glucose, fructose or sucrose.

  9. Optical rotation and electron spin resonance of an electro-optically active polythiophene

    International Nuclear Information System (INIS)

    Goto, Hiromasa

    2010-01-01

    Graphical abstract: The electro-chiroptical polythiophene displays optical rotation at wavelengths corresponding to the doping band observable in the absorption spectra. The formation of polarons on the main-chain is confirmed by electron spin resonance measurements. - Abstract: A chiroptical polythiophene, is synthesized by electrolytic polymerization in a cholesteric liquid crystal electrolyte solution. The polymer displays a fingerprint texture similar to that of the cholesteric electrolyte solution. Upon electrochemical doping, the polymer displays optical rotation at wavelengths corresponding to the doping band observable in the absorption spectra. The formation of polarons on the main-chain is confirmed by electron spin resonance measurements. The results demonstrate the intermolecular chirality of polarons in this π-conjugated polymer, indicating continuum delocalized polarons are in a three-dimensional helical environment.

  10. Electron spin resonance of paramagnetic defects and related charge carrier traps in complex oxide scintillators

    Czech Academy of Sciences Publication Activity Database

    Laguta, Valentyn; Nikl, Martin

    2013-01-01

    Roč. 250, č. 2 (2013), s. 254-260 ISSN 0370-1972 R&D Projects: GA MŠk(CZ) LM2011029; GA ČR GAP204/12/0805; GA AV ČR IAA100100810 Grant - others:SAFMAT(XE) CZ.2.16/3.1.00/22132 Institutional support: RVO:68378271 Keywords : scintillators * point defects * electron spin resonance * polarons Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.605, year: 2013

  11. Electron spin resonance of radicals and metal complexes

    International Nuclear Information System (INIS)

    1993-01-01

    The materials are a collection of extended synopsis of papers presented at the conference sessions. The broad area of magnetic techniques applications has been described as well as their spectra interpretation methods. The ESR, NMR, ENDOR and spin echo were applied for studying the radiation and UV induced radicals in chemical and biological systems. Also in the study of complexes of metallic ions (having the paramagnetic properties) and their interaction with the matrix, the magnetic techniques has been commonly used. They are also very convenient tool for the study of reaction kinetics and mechanism as well as interaction of paramagnetic species with themselves and crystal lattice or with the surface as for thee catalytic processes

  12. Nuclear effects in electron spin resonance of crystalline solids

    International Nuclear Information System (INIS)

    Ursu, I.; Nistor, S.V.

    1976-01-01

    A survey on the theory of paramagnetic ions in crystals is given. Some recent applications in which nuclear properties are studied by means of the ESR method are presented against this background. Finer effects in the hyperfine structure of ESR spectra, temperature dependance of the hyperfine coupling of S-state ions, observation of nuclear isotopic shift in ESR represent the applications discussed

  13. Spectroscopy study of electron spin resonance of coal oxidation of different rank; Estudio por espectroscopia de resonancia espin electron de la oxidacion de carbones de diferente rango

    Energy Technology Data Exchange (ETDEWEB)

    Enciso Prieto, Hector Manuel

    1992-07-01

    The present work constitutes an initial step for the knowledge of the coal oxidation, with the purpose of preventing the adverse influences caused by this phenomenon in the physical-chemical characteristics and in the tendency to the spontaneous combustion. Since the knowledge the influence of the free radicals in this process, their relative concentration was measured by means of the use of the technique of resonance spin electron. This technique measures the absorption of electromagnetic radiation, generally in the microwaves region, for the materials that not have electrons matched up in a strong magnetic field. In the essays of oxidation three coal of different range and different characteristics of mass were used and it was studied the influence of the temperature, particle size and the range. The results showed that the coal of Guacheta (bituminous low in volatile) it presents bigger concentration of free radicals, after the reaction with the atmospheric oxygen, with regard to the coal of the Cerrejon (bituminous high in volatile B) and Amaga (bituminous high in volatile C). Although this doesn't indicate that the coal of Guacheta is that more easily is oxidized, but rather it possibly presents stabilization of radicals for resonance. It concluded that there are differences in the oxidation mechanism between coal of different rank and different agglomeration properties.

  14. Electron spin resonance of vanadium(4)-thallium(1) dithiocarbamate complexes

    International Nuclear Information System (INIS)

    Ivanov, A.V.; Solozhenkin, P.M.; Baratova, Z.R.; Klyashtornyj, V.B.; Uskov, V.Yu.

    1990-01-01

    Heteronuclear vanadium(4), thallium(1) dithiocarbanate complexes of the composition TlVO(Dtc) 3 and Tl 2 VO(Dtc) 4 under conditions of magnetic dilution were studied by ESR spectroscopy. Magnetically diluted complexes were prepared by coprecipitation from aqueous solutions of thallium(1) and oxovanadium(2) by solutions of sodium diethyldithiocarbamate, dibutyldithiocarbamate, hexamethylenedithiocarbamate, taken in superstoichiometric excess. Analysis of parameters of ESR spectra of the complexes synthesized shows that thallium atoms are not included in the first coordination sphere of oxovanadium(2), and chelate node VS 4 in thallium(1) complex lattice practically preserves its plane quadratic structure

  15. The structure and properties of free radicals: An electron spin resonance study of radiation damage to nucleic acid and protein components and to some sulfur-substituted derivitives

    International Nuclear Information System (INIS)

    Sagstuen, E.

    1979-01-01

    When cellular systems are exposed to ionizing radiation the long-term effects may range from minor disturbances to such dramatic changes as mutations and cell death. The processes leading to these macroscopical injuries are primarily confined at the molecular level. In all models aimed at a description of the action of radiation at the molecular level the formation of free radicals (which are species containing unpaired electrons) is a central concept. The technique of ESR spectroscopy is uniquely suited to study free radicals, as it is based on resonance absorption of energy by unpaired electrons in a magnetic field. ESR spectroscopy makes it possible to detect free radicals and, in some cases, to identify them. In order to study free radicals by ESR it is necessary to build up a sufficient number of unpaired spins in the sample (approximately 10 11 or more, depending on the shape of the resonance). This may be different techniques have been used to trap the induced radicals or to attain a sufficient steady state concentration level. A procedure which seems to contain a large amount of information is to irradiate at low temperatures, and, by subsequent heat-treatment of the sample to study the reactions and fate of the induced radicals. In this thesis single crystal studies of aromatic amino acids and pyrimidine derivitives together with some substituted purine derivitives are presented, and the results are discussed in relation to the present knowledge about radical formation in these classes of compounds. Single crystal studies of some sulfur-containing aromatic compounds have been presented with the purpose of shedding light on the electronic structure of sulfur-centred radicals. (JIW)

  16. Irradiation detection of coffee mate by electron spin resonance (ESR)

    Energy Technology Data Exchange (ETDEWEB)

    Ozsayin, Fulya [Physics Engineering Department, Hacettepe University, 06800 Ankara (Turkey); Polat, Mustafa, E-mail: polat@hacettepe.edu.t [Physics Engineering Department, Hacettepe University, 06800 Ankara (Turkey)

    2011-06-15

    Un-irradiated coffee mate samples do not exhibit any ESR signal. However, the samples exposed to UV and gamma radiation exhibit an ESR singlet and a large unresolved ESR signal, respectively. The dose-response curves of the samples exposed to UV and gamma radiations were found to be described well by an exponential and linear functions, respectively. Variable temperature and fading studies at room temperature showed that the radiation-induced radicals in coffee mate sample are very sensitive to temperature. The discrimination between un-irradiated and irradiated coffee mate samples can be done just comparing their ESR spectra. However, determination of the radiation dose received by the sample cannot be possible because of the fast decay of signal intensity at room temperature.

  17. Dating the Naisiusiu Beds, Olduvai Gorge, by electron spin resonance

    Science.gov (United States)

    Skinner, A. R.; Hay, R. L.; Masao, F.; Blackwell, B. A. B.

    2003-05-01

    The lower beds at Olduvai Gorge are well known for containing early hominid fossils and Oldowan stone tools, and their ages have been established by 40Ar/ 39Ar dating and paleomagnetic stratigraphy. Ages are generally less certain for the upper deposits at Olduvai Gorge because of the scarcity of datable tuffs. The youngest archaeologically significant site at Olduvai is microlithic LSA, which lies in the type section of the Naisiusiu Beds. The age for the site is controversial, with 14C dates of 17,000-17,550 (Hay, R.L., 1976 Geology of Olduvai Gorge, University of California Press, Berkeley) and >42,000 BP (Manega, P.C., 1993. Geochronology, geochemistry, and isotopic study of the Plio-Pleistocene Hominid sites and the Ngorongoro Volcanic Highland in Northern Tanzania. Unpublished Ph.D. Thesis, University of Colorado, Boulder, CO). The tuff bed in the zone with artifacts does not contain materials datable by 40Ar/ 39Ar, and some other dating method was needed. In the summer of 2001, five equid teeth were collected from the type Naisiusiu site. Another tooth had previously been collected. ESR ages have been determined for three teeth from the archaeological level and their ages cluster around 62±5 ka, assuming linear uranium uptake. Another tooth from a level without artifacts and believed to be significantly younger dated to 39±5 ka, again assuming LU. These dates are considerably older than previous estimates and suggest that the East African MSA/LSA transition occurred very early.

  18. Electron spin resonance for the detection of long-range spin nematic order

    Science.gov (United States)

    Furuya, Shunsuke C.; Momoi, Tsutomu

    2018-03-01

    Spin nematic phase is a quantum magnetic phase characterized by a quadrupolar order parameter. Since the quadrupole operators are directly coupled to neither the magnetic field nor the neutron, currently, it is an important issue to develop a method for detecting the long-range spin nematic order. In this paper, we propose that electron spin resonance (ESR) measurements enable us to detect the long-range spin nematic order. We show that the frequency of the paramagnetic resonance peak in the ESR spectrum is shifted by the ferroquadrupolar order parameter together with other quantities. The ferroquadrupolar order parameter is extractable from the angular dependence of the frequency shift. In contrast, the antiferroquadrupolar order parameter is usually invisible in the frequency shift. Instead, the long-range antiferroquadrupolar order yields a characteristic resonance peak in the ESR spectrum, which we call a magnon-pair resonance peak. This resonance corresponds to the excitation of the bound magnon pair at the wave vector k =0 . Reflecting the condensation of bound magnon pairs, the field dependence of the magnon-pair resonance frequency shows a singular upturn at the saturation field. Moreover, the intensity of the magnon-pair resonance peak shows a characteristic angular dependence and it vanishes when the magnetic field is parallel to one of the axes that diagonalize the weak anisotropic interactions. We confirm these general properties of the magnon-pair resonance peak in the spin nematic phase by studying an S =1 bilinear-biquadratic model on the square lattice in the linear flavor-wave approximation. In addition, we argue applications to the S =1/2 frustrated ferromagnets and also the S =1/2 orthogonal dimer spin system SrCu2(BO3)2, both of which are candidate materials of spin nematics. Our theory for the antiferroquadrupolar ordered phase is consistent with many features of the magnon-pair resonance peak experimentally observed in the low

  19. Simulation of electron spin resonance spectroscopy in diverse environments: An integrated approach

    Science.gov (United States)

    Zerbetto, Mirco; Polimeno, Antonino; Barone, Vincenzo

    2009-12-01

    We discuss in this work a new software tool, named E-SpiReS (Electron Spin Resonance Simulations), aimed at the interpretation of dynamical properties of molecules in fluids from electron spin resonance (ESR) measurements. The code implements an integrated computational approach (ICA) for the calculation of relevant molecular properties that are needed in order to obtain spectral lines. The protocol encompasses information from atomistic level (quantum mechanical) to coarse grained level (hydrodynamical), and evaluates ESR spectra for rigid or flexible single or multi-labeled paramagnetic molecules in isotropic and ordered phases, based on a numerical solution of a stochastic Liouville equation. E-SpiReS automatically interfaces all the computational methodologies scheduled in the ICA in a way completely transparent for the user, who controls the whole calculation flow via a graphical interface. Parallelized algorithms are employed in order to allow running on calculation clusters, and a web applet Java has been developed with which it is possible to work from any operating system, avoiding the problems of recompilation. E-SpiReS has been used in the study of a number of different systems and two relevant cases are reported to underline the promising applicability of the ICA to complex systems and the importance of similar software tools in handling a laborious protocol. Program summaryProgram title: E-SpiReS Catalogue identifier: AEEM_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEEM_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: GPL v2.0 No. of lines in distributed program, including test data, etc.: 311 761 No. of bytes in distributed program, including test data, etc.: 10 039 531 Distribution format: tar.gz Programming language: C (core programs) and Java (graphical interface) Computer: PC and Macintosh Operating system: Unix and Windows Has the code been vectorized or

  20. A study of the deep structure of the energy landscape of glassy polystyrene: the exponential distribution of the energy barriers revealed by high-field electron spin resonance spectroscopy

    International Nuclear Information System (INIS)

    Bercu, V; Martinelli, M; Massa, C A; Pardi, L A; Leporini, D

    2004-01-01

    The reorientation of one small paramagnetic molecule (spin probe) in glassy polystyrene (PS) is studied by high-field electron spin resonance spectroscopy at two different Larmor frequencies (190 and 285 GHz). The exponential distribution of the energy barriers for the rotational motion of the spin probe is unambiguously evidenced at both 240 and 270 K. The same shape for the distribution of the energy barriers of PS was evidenced by the master curves provided by previous mechanical and light scattering studies. The breadth of the energy barrier distribution of the spin probe is in the range of the estimates of the breadth of the PS energy barrier distribution. The evidence that the deep structure of the energy landscape of PS exhibits the exponential shape of the energy barrier distribution agrees with the results from extreme-value statistics (Bouchaud and Mezard 1997 J. Phys. A: Math. Gen. 30 7997) and the trap model by Bouchaud and co-workers (1996 J. Phys. A: Math. Gen. 29 3847, 2001 Phys. Rev. B 64 104417). (letter to the editor)

  1. Magnetic defects in chemically converted graphene nanoribbons: electron spin resonance investigation

    Directory of Open Access Journals (Sweden)

    Srinivasa Rao Singamaneni

    2014-04-01

    Full Text Available Electronic spin transport properties of graphene nanoribbons (GNRs are influenced by the presence of adatoms, adsorbates and edge functionalization. To improve the understanding of the factors that influence the spin properties of GNRs, local (element spin-sensitive techniques such as electron spin resonance (ESR spectroscopy are important for spintronics applications. Here, we present results of multi-frequency continuous wave (CW, pulse and hyperfine sublevel correlation (HYSCORE ESR spectroscopy measurements performed on oxidatively unzipped graphene nanoribbons (GNRs, which were subsequently chemically converted (CCGNRs with hydrazine. ESR spectra at 336 GHz reveal an isotropic ESR signal from the CCGNRs, of which the temperature dependence of its line width indicates the presence of localized unpaired electronic states. Upon functionalization of CCGNRs with 4-nitrobenzene diazonium tetrafluoroborate, the ESR signal is found to be 2 times narrower than that of pristine ribbons. NH3 adsorption/desorption on CCGNRs is shown to narrow the signal, while retaining the signal intensity and g value. The electron spin-spin relaxation process at 10 K is found to be characterized by slow (163 ns and fast (39 ns components. HYSCORE ESR data demonstrate the explicit presence of protons and 13C atoms. With the provided identification of intrinsic point magnetic defects such as proton and 13C has been reported, which are roadblocks to spin travel in graphene-based materials, this work could help in advancing the present fundamental understanding on the edge-spin (or magnetic-based transport properties of CCGNRs.

  2. Magnetic defects in chemically converted graphene nanoribbons: electron spin resonance investigation

    Energy Technology Data Exchange (ETDEWEB)

    Singamaneni, Srinivasa Rao, E-mail: ssingam@ncsu.edu [INPAC – Institute for Nanoscale Physics and Chemistry, Semiconductor Physics Laboratory, K.U. Leuven, Celestijnenlaan 200D, B–3001 Leuven (Belgium); Materials Science Division, Army Research Office, Research Triangle Park, North Carolina 27709 (United States); Department of Material Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695 (United States); Stesmans, Andre [INPAC – Institute for Nanoscale Physics and Chemistry, Semiconductor Physics Laboratory, K.U. Leuven, Celestijnenlaan 200D, B–3001 Leuven (Belgium); Tol, Johan van [National High Magnetic Field Laboratory, Florida State University, 1800 E. Paul Dirac Drive, Tallahassee, Florida 32310 (United States); Kosynkin, D. V. [Department of Chemistry, Smalley Institute for Nanoscale Science and Technology, Rice University, MS-222, 6100 Main Street, Houston, Texas 77005 (United States); Tour, James M. [Department of Chemistry, Smalley Institute for Nanoscale Science and Technology, Rice University, MS-222, 6100 Main Street, Houston, Texas 77005 (United States); Department of Mechanical Engineering and Materials Science, Smalley Institute for Nanoscale Science and Technology, Rice University, MS-222, 6100 Main Street, Houston, Texas 77005 (United States); Smalley Institute for Nanoscale Science and Technology, Rice University, MS-222, 6100 Main Street, Houston, Texas 77005, USA. (United States)

    2014-04-15

    Electronic spin transport properties of graphene nanoribbons (GNRs) are influenced by the presence of adatoms, adsorbates and edge functionalization. To improve the understanding of the factors that influence the spin properties of GNRs, local (element) spin-sensitive techniques such as electron spin resonance (ESR) spectroscopy are important for spintronics applications. Here, we present results of multi-frequency continuous wave (CW), pulse and hyperfine sublevel correlation (HYSCORE) ESR spectroscopy measurements performed on oxidatively unzipped graphene nanoribbons (GNRs), which were subsequently chemically converted (CCGNRs) with hydrazine. ESR spectra at 336 GHz reveal an isotropic ESR signal from the CCGNRs, of which the temperature dependence of its line width indicates the presence of localized unpaired electronic states. Upon functionalization of CCGNRs with 4-nitrobenzene diazonium tetrafluoroborate, the ESR signal is found to be 2 times narrower than that of pristine ribbons. NH{sub 3} adsorption/desorption on CCGNRs is shown to narrow the signal, while retaining the signal intensity and g value. The electron spin-spin relaxation process at 10 K is found to be characterized by slow (163 ns) and fast (39 ns) components. HYSCORE ESR data demonstrate the explicit presence of protons and {sup 13}C atoms. With the provided identification of intrinsic point magnetic defects such as proton and {sup 13}C has been reported, which are roadblocks to spin travel in graphene-based materials, this work could help in advancing the present fundamental understanding on the edge-spin (or magnetic)-based transport properties of CCGNRs.

  3. Formation of radicals in coal pyrolysis examined by electron spin resonance

    Directory of Open Access Journals (Sweden)

    Tong Chang

    2017-09-01

    Full Text Available Electron spin resonance (ESR spectroscopy is used to study materials with unpaired electrons, such as organic radicals and metal complexes. This method can also be used to follow radical reactions during pyrolysis of carbonaceous materials. However, the temperature dependence of ESR measurement should be considered. To enable reasonable comparisons, results measured at different temperatures must be converted. In this study, we investigated the behavior of free radicals in the process of coal pyrolysis using in situ and ex situ ESR. The ESR data were collected at both pyrolysis and room temperatures, and apparent differences were analyzed. The differences were diminished when our data were converted to the same measurement temperature level based on the Boltzmann distribution law. Furthermore, we investigated the effects of process conditions on the behavior of free radicals in the solid phase of coal. We found that temperature is the most important factor determining the formation and behavior of free radicals in the solid phase, followed by the residence time. Relatively active radicals were quenched by hydrogen-donor solvents to some degree, while stable radicals remained.

  4. High Radiation Doses from Radiotherapy Measured by Electron Spin Resonance in Dental Enamel

    International Nuclear Information System (INIS)

    Pass, B.; Wood, R.E.; Liu, F.; McLean, M.; Aldrich, J.E.

    1998-01-01

    For radiotherapy, an error in the complicated treatment planning or treatment procedure is a possibility, however remote. Thus, in the present study electron spin resonance (ESR) in dental enamel was investigated for the first time as a means of retrospective dosimetry for validating applied radiotherapy doses to the head and neck regions. Total absorbed radiation doses measured by ESR in dental enamel were compared to the doses determined by treatment planning for 19 patients who received radiotherapy for intra-oral, pharyngeal or laryngeal malignancies, or total-body irradiation prior to bone marrow transplants (BMT). For the 15 tumour irradiations there was, within the framework of the tooth positions as presented, general agreement between the treatment planned and ESR dose determinations. There were, however, both significant and minor discrepancies. For the BMT patients there were major discrepancies for two of the four patients investigated. This study indicates that ESR in dental enamel may be useful as the only means of retrospective dosimetry for validating applied radiotherapy doses after treatment. However, further research must be carried out before this technique can be accepted as accurate and reliable. (author)

  5. Contribution to the study of molecular movements in cyclohexane by electron spin resonance and electron-nuclear double resonance using a radical probe; Contribution a l'etude des mouvements moleculaires dans le cyclohexane par resonance paramagnetique electronique et double resonance electronique-nucleaire a l'aide d'une sonde radicalaire

    Energy Technology Data Exchange (ETDEWEB)

    Volino, F [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

    1969-07-01

    Solutions of stable free radicals of the nitroxide type have been studied as a function of temperature. In the plastic or globular state, the cyclohexane molecules have rapid rotational and diffusional movements. They transmit this movement to dissolved free radicals. Conversely, measurements by electron spin resonance of the absolute movement of the radicals, and by electron nuclear double resonance of their movement relative to the cyclohexane molecules give very precise methods for local analyses of the movement present in the cyclohexane matrix. The principle of these techniques makes up the 'radical probe method'. (author) [French] Des solutions de radicaux libres stables, du type nitroxyde dans le cyclohexane ont ete etudiees, en fonction de la temperature. Les molecules de cyclohexane, dans l'etat plastique ou globulaire, sont animees de mouvements rapides de rotation sur elles-memes et de diffusion. Elles transmettent leur mobilite aux radicaux libres dissous. Reciproquement, la mesure du mouvement absolu des radicaux, a l'aide de la resonance paramagnetique electronique, et celle du mouvement relatif des radicaux et des molecules de cyclohexane par double resonance electronique-nucleaire, constituent des methodes tres precises pour analyser localement les mouvements presents dans la matrice de cyclohexane. Ce principe et ces techniques constituent la 'methode de la sonde radicalaire'. (auteur)

  6. Contribution to the study of molecular movements in cyclohexane by electron spin resonance and electron-nuclear double resonance using a radical probe; Contribution a l'etude des mouvements moleculaires dans le cyclohexane par resonance paramagnetique electronique et double resonance electronique-nucleaire a l'aide d'une sonde radicalaire

    Energy Technology Data Exchange (ETDEWEB)

    Volino, F. [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

    1969-07-01

    Solutions of stable free radicals of the nitroxide type have been studied as a function of temperature. In the plastic or globular state, the cyclohexane molecules have rapid rotational and diffusional movements. They transmit this movement to dissolved free radicals. Conversely, measurements by electron spin resonance of the absolute movement of the radicals, and by electron nuclear double resonance of their movement relative to the cyclohexane molecules give very precise methods for local analyses of the movement present in the cyclohexane matrix. The principle of these techniques makes up the 'radical probe method'. (author) [French] Des solutions de radicaux libres stables, du type nitroxyde dans le cyclohexane ont ete etudiees, en fonction de la temperature. Les molecules de cyclohexane, dans l'etat plastique ou globulaire, sont animees de mouvements rapides de rotation sur elles-memes et de diffusion. Elles transmettent leur mobilite aux radicaux libres dissous. Reciproquement, la mesure du mouvement absolu des radicaux, a l'aide de la resonance paramagnetique electronique, et celle du mouvement relatif des radicaux et des molecules de cyclohexane par double resonance electronique-nucleaire, constituent des methodes tres precises pour analyser localement les mouvements presents dans la matrice de cyclohexane. Ce principe et ces techniques constituent la 'methode de la sonde radicalaire'. (auteur)

  7. Electron spin resonance (ESR dose measurement in bone of Hiroshima A-bomb victim.

    Directory of Open Access Journals (Sweden)

    Angela Kinoshita

    Full Text Available Explosion of the bombs in Hiroshima and Nagasaki corresponds to the only historical moment when atomic bombs were used against civilians. This event triggered countless investigations into the effects and dosimetry of ionizing radiation. However, none of the investigations has used the victims' bones as dosimeter. Here, we assess samples of bones obtained from fatal victims of the explosion by Electron Spin Resonance (ESR. In 1973, one of the authors of the present study (SM traveled to Japan and conducted a preliminary experiment on the victims' bone samples. The idea was to use the paramagnetism induced in bone after irradiation to measure the radiation dose. Technological advances involved in the construction of spectrometers, better knowledge of the paramagnetic center, and improvement in signal processing techniques have allowed us to resume the investigation. We obtained a reconstructed dose of 9.46 ± 3.4 Gy from the jawbone, which was compatible with the dose distribution in different locations as measured in non-biological materials such as wall bricks and roof tiles.

  8. Conversion from tooth enamel dose to organ doses for electron spin resonance dosimetry

    International Nuclear Information System (INIS)

    Takahashi, Fumiaki; Yamaguchi, Yasuhiro; Saito, Kimiaki; Hamada, Tatsuji

    2002-01-01

    Conversion from tooth enamel dose to organ doses was analyzed to establish a method of retrospective individual dose assessment against external photon exposure by electron spin resonance (ESR) dosimetry. Dose to tooth enamel was obtained by Monte Carlo calculations using a modified MIRD-type phantom with a teeth part. The calculated tooth enamel doses were verified by measurements with thermo-luminescence dosimeters inserted in a physical head phantom. Energy and angular dependences of tooth enamel dose were compared with those of other organ doses. Additional Monte Carlo calculations were performed to study the effect of human model on the tooth enamel dose with a voxel-type phantom, which was based on computed tomography images of the physical phantom. The data derived with the modified MIRD-type phantom were applied to convert from tooth enamel dose to organ doses against external photon exposure in a hypothesized field, where scattered radiation was taken into account. The results indicated that energy distribution of photons incident to a human body is required to evaluate precisely an individual dose based on ESR dosimetry for teeth. (author)

  9. Tooth enamel electron spin resonance dosimetry of people living in the area with lime tobacco custom

    International Nuclear Information System (INIS)

    Jiao Ling; Zhang Wenyi; Ding Yanqiu

    2010-01-01

    Objective: To study the effect of the custom of long term chewing lime tobacco on human tooth enamel electron spin resonance (ESR) dosimetry. Methods: A total of 20 enamel samples from lingual parts of adults teeth collected in Bombay, India were obtained by mechanical method. Some enamel samples from Japanese adults were extracted and 10 mixed samples were prepared. Enamel samples were exposed to different doses of 60 Co γ-rays several times, and ESR spectra were measured after exposure. Results: ESR background signals of 9 Bombay samples were found 1.5-3.3 times higher than those of Japanese mixed samples. The γ-ray dose responses of dosimetric signal with higher background level were a little lower, and the average sensitivity was (0.42±0.03) mGy, which was close to that of Japanese mixed samples. Conclusions: The average level of background signals of Bombay samples was much higher than that of other non-chewing tobacco area, which was possibly caused by tobacco area, which was possibly caused by tobacco lime, the main component in chewing tobacco productions, and it would help to explore its special influences on ESR, and improve dose reconstruction in accuracy. (authors)

  10. Electron spin resonance (ESR) dose measurement in bone of Hiroshima A-bomb victim

    Science.gov (United States)

    2018-01-01

    Explosion of the bombs in Hiroshima and Nagasaki corresponds to the only historical moment when atomic bombs were used against civilians. This event triggered countless investigations into the effects and dosimetry of ionizing radiation. However, none of the investigations has used the victims’ bones as dosimeter. Here, we assess samples of bones obtained from fatal victims of the explosion by Electron Spin Resonance (ESR). In 1973, one of the authors of the present study (SM) traveled to Japan and conducted a preliminary experiment on the victims’ bone samples. The idea was to use the paramagnetism induced in bone after irradiation to measure the radiation dose. Technological advances involved in the construction of spectrometers, better knowledge of the paramagnetic center, and improvement in signal processing techniques have allowed us to resume the investigation. We obtained a reconstructed dose of 9.46 ± 3.4 Gy from the jawbone, which was compatible with the dose distribution in different locations as measured in non-biological materials such as wall bricks and roof tiles. PMID:29408890

  11. Circuits and systems for CW and pulsed high-field electron spin resonance

    OpenAIRE

    David Robert, Bolton

    2006-01-01

    This thesis is concerned with the design and realisation of components for a new state of the art 94GHz Electron Spin Resonance (ESR) spectrometer capable of operating in both pulsed and CW modes. The complete spectrometer is designed to provide phase coherent 1kW peak power sub-nanosecond π/2 pulses having variable duration and repetition rate. The mm-wave response of a paramagnetic sample to these pulses is detected with a superheterodyne detector. Such a system would offer a step change in...

  12. Theory of Electric-Field Effects on Electron-Spin-Resonance Hyperfine Couplings

    International Nuclear Information System (INIS)

    Karna, S.P.

    1997-01-01

    A quantum mechanical theory of the effects of a uniform electric field on electron-spin-resonance hyperfine couplings is presented. The electric-field effects are described in terms of perturbation coefficients which can be used to probe the local symmetry as well as the strength of the electric field at paramagnetic sites in a solid. Results are presented for the first-order perturbation coefficients describing the Bloembergen effect (linear electric-field effect on hyperfine coupling tensor) for the O atom and the OH radical. copyright 1997 The American Physical Society

  13. Comparative investigation on electron spin resonance dosimetry of tooth enamel of cow and human

    International Nuclear Information System (INIS)

    Jiao Ling; Zhang Wenyi; Ding Yanqiu; Kou Mingying

    2010-01-01

    The enamel samples from cow teeth and human teeth were irradiated with 137 Cs γ ray. Their electron spin resonance (ESR) spectra pre and post-irradiation were weaker than those of human. Mass of each sample is 100 mg, the dosimetric signal intensity of cow enamel increased with the radiation dose; the averaged radiation response of cow samples was (34.4±2.0) Gy -1 , very close to the average response of human tooth samples (36.3±2.9) Gy -1 . Therefore cow teeth can be used for retrospective radiation dosimetry when human teeth are unavailable. (authors)

  14. Electron spin resonance signal from a tetra-interstitial defect in silicon

    CERN Document Server

    Mchedlidze, T

    2003-01-01

    The Si-B3 electron spin resonance (ESR) signal from agglomerates of self-interstitials was detected for the first time in hydrogen-doped float-zone-grown silicon samples subjected to annealing after electron irradiation. Previously this signal had been detected only in neutron- or proton-irradiated silicon samples. The absence of obscuring ESR peaks for the investigated samples at applied measurement conditions allowed an investigation of the hyperfine structure of the Si-B3 spectra. The analysis supports assignment of a tetra-interstitial defect as the origin of the signal.

  15. An electron spin resonance study on the gamma-irradiation of urea, urea- d4, 1-3-dimethylurea, 1-3-diethylurea and 1,1',3,3'-tetramthylurea

    International Nuclear Information System (INIS)

    Kang, Y.S.; McManus, H.J.D.; Kevan, L.

    1994-01-01

    Urea, urea-d 4 , 1,3-dimethylurea, 1,3-diethylurea powder and 1,1',3,3'-tetramethylurea, and their solutions in D 2 O were γ-irradiated with 0.0882 kGy both at room temperature and at 77 K. The product radicals were identified with X-band electron spin resonance, based on the g-factor and hyperfine coupling constants. The radicals formed from urea and urea-d 4 were identified as nitrogen-centered and resulted from N-H bond dissociation. The radicals produced from 1,3-dimethylurea, 1,3-diethylurea and 1,1',3,3'-tetramethylurea were identified as carbon-centered and resulted from C-H bond cleavage. The electron spin resonance signals of 1,3-dimethylurea, 1,3-diethylurea and 1,1',3,3'-tetramethylurea are similar in both the powder and D 2 O solution. The radicals observed from 1,3-dimethylurea, 1,3-diethylurea and 1,1',3,3'-tetramethylurea were identified as . NH-CH 2 , . NH-CHCH 3 and . (CH 3 )(CH 2 ), respectively. (author)

  16. 14 GHz longitudinally detected electron spin resonance using microHall sensors

    Science.gov (United States)

    Bouterfas, M.; Mouaziz, S.; Popovic, R. S.

    2017-09-01

    In this work we developed a home-made LOngitudinally Detected Electron Spin Resonance (LODESR) spectrometer based on a microsize Hall sensor. A coplanar waveguide (CPW)-resonator is used to induce microwave-excitation on the sample at 14 GHz. We used InSb cross-shaped Hall devices with active areas of (10 μm × 10 μm) and (5 μm × 5 μm) . Signal intensities of the longitudinal magnetization component of DPPH and YIG samples of volumes about (10 μm) 3 and (5 μm) 3 , are measured under amplitude and frequency modulated microwave magnetic field generated by the CPW-resonator. At room temperature, 109spins /G √Hz sensitivity is achieved for 0.2mT linewidth, a result which is still better than most of inductive detected LODESR sensitivities.

  17. Feasibility study of entrance and exit dose measurements at the contra lateral breast with alanine/electron spin resonance dosimetry in volumetric modulated radiotherapy of breast cancer

    Science.gov (United States)

    Wagner, Daniela M.; Hüttenrauch, Petra; Anton, Mathias; von Voigts-Rhetz, Philip; Zink, Klemens; Wolff, Hendrik A.

    2017-07-01

    The Physikalisch-Technische Bundesanstalt has established a secondary standard measurement system for the dose to water, D W, based on alanine/ESR (Anton et al 2013 Phys. Med. Biol. 58 3259-82). The aim of this study was to test the established measurement system for the out-of-field measurements of inpatients with breast cancer. A set of five alanine pellets were affixed to the skin of each patient at the contra lateral breast beginning at the sternum and extending over the mammilla to the distal surface. During 28 fractions with 2.2 Gy per fraction, the accumulated dose was measured in four patients. A cone beam computer tomography (CBCT) scan was generated for setup purposes before every treatment. The reference CT dataset was registered rigidly and deformably to the CBCT dataset for 28 fractions. To take the actual alanine pellet position into account, the dose distribution was calculated for every fraction using the Acuros XB algorithm. The results of the ESR measurements were compared to the calculated doses. The maximum dose measured at the sternum was 19.9 Gy  ±  0.4 Gy, decreasing to 6.8 Gy  ±  0.2 Gy at the mammilla and 4.5 Gy  ±  0.1 Gy at the distal surface of the contra lateral breast. The absolute differences between the calculated and measured doses ranged from  -1.9 Gy to 0.9 Gy. No systematic error could be seen. It was possible to achieve a combined standard uncertainty of 1.63% for D W  =  5 Gy for the measured dose. The alanine/ESR method is feasible for in vivo measurements.

  18. Electron spin resonance and its application to heat treated carbonaceous materials

    International Nuclear Information System (INIS)

    Emmerich, Francisco Guilherme

    1993-01-01

    This work presents the basic characteristics of the electron spin resonance technique, also called paramagnetic resonance, being discussed its application to heat treated carbonaceous materials. In the low heat treatment temperature (HTT) range (below 700 deg C) the organic free radical are the predominant unpaired spin center, which play a key role in the process of carbonization and meso phase formation. At higher temperatures, it is possible to make correlations between the low H T T range and the high HTT range (above 130 deg C), where the predominant unpaired spin center are the free charge carriers (free electrons) of the graphite like crystallites of the material, which are formed by the carbonization process. (author)

  19. Broadband electron spin resonance from 500 MHz to 40 GHz using superconducting coplanar waveguides

    Science.gov (United States)

    Clauss, Conrad; Bothner, Daniel; Koelle, Dieter; Kleiner, Reinhold; Bogani, Lapo; Scheffler, Marc; Dressel, Martin

    2013-04-01

    We present non-conventional electron spin resonance (ESR) experiments based on microfabricated superconducting Nb thin film waveguides. A very broad frequency range, from 0.5 to 40 GHz, becomes accessible at low temperatures down to 1.6 K and in magnetic fields up to 1.4 T. This allows for an accurate inspection of the ESR absorption position in the frequency domain, in contrast to the more common observation as a function of magnetic field. We demonstrate the applicability of frequency-swept ESR on Cr3+ atoms in ruby as well as on organic radicals of the nitronyl-nitroxide family. Measurements between 1.6 and 30 K reveal a small frequency shift of the ESR and a resonance broadening below the critical temperature of Nb, which we both attribute to a modification of the magnetic field configuration due to the appearance of shielding supercurrents in the waveguide.

  20. Use of electron spin resonance technique for identifying of irradiated foods

    International Nuclear Information System (INIS)

    El-Shiemy, S.M.E

    2008-01-01

    The present investigation was carried out to establish the electron spin resonance (ESR) technique for identifying of some irradiated foodstuffs, i.e. dried fruits (fig and raisin), nuts (almond and pistachio) and spices (fennel and thyme). Gamma rays were used as follows: 0, 1, 3 and 5 kGy were given for dried fruits, while 0, 2, 4 and 6 kGy were given for nuts. In addition, 0, 5, 10 and 15 kGy were given for spices. All treatments were stored at room temperature (25±2 degree C) for six months to study the possibility of detecting its irradiation treatment by ESR spectroscopy. The obtained results indicated that ESR signal intensities of all irradiated samples were markedly increased correspondingly with irradiation dose as a result of free radicals generated by gamma irradiation. So, all irradiated samples under investigation could be differentiated from unirradiated ones immediately after irradiation treatment. The decay that occur in free radicals which responsible of ESR signals during storage periods at ambient temperature showed a significant minimize in ESR signal intensities of irradiated samples. Therefore, after six months of ambient storage the detection was easily possible for irradiated dried fig with dose ≥ 3 kGy and for all irradiated raisin and pistachio (shell). Also, it was possible for irradiated fennel with dose ≥ 10 kGy and for irradiated thyme with dose ≥15 kGy. In contrast, the identification of all irradiated samples of almond (shell as well as edible part) and pistachio (edible part) was impossible after six months of ambient storage.

  1. Use of electron spin resonance technique for identifying of irradiated foods

    Energy Technology Data Exchange (ETDEWEB)

    El-Shiemy, S M E

    2008-07-01

    The present investigation was carried out to establish the electron spin resonance (ESR) technique for identifying of some irradiated foodstuffs, i.e. dried fruits (fig and raisin), nuts (almond and pistachio) and spices (fennel and thyme). Gamma rays were used as follows: 0, 1, 3 and 5 kGy were given for dried fruits, while 0, 2, 4 and 6 kGy were given for nuts. In addition, 0, 5, 10 and 15 kGy were given for spices. All treatments were stored at room temperature (25{+-}2 degree C) for six months to study the possibility of detecting its irradiation treatment by ESR spectroscopy. The obtained results indicated that ESR signal intensities of all irradiated samples were markedly increased correspondingly with irradiation dose as a result of free radicals generated by gamma irradiation. So, all irradiated samples under investigation could be differentiated from unirradiated ones immediately after irradiation treatment. The decay that occur in free radicals which responsible of ESR signals during storage periods at ambient temperature showed a significant minimize in ESR signal intensities of irradiated samples. Therefore, after six months of ambient storage the detection was easily possible for irradiated dried fig with dose {>=} 3 kGy and for all irradiated raisin and pistachio (shell). Also, it was possible for irradiated fennel with dose {>=} 10 kGy and for irradiated thyme with dose {>=}15 kGy. In contrast, the identification of all irradiated samples of almond (shell as well as edible part) and pistachio (edible part) was impossible after six months of ambient storage.

  2. Applications of electron spin resonance to some problems of radiation chemistry

    International Nuclear Information System (INIS)

    Chachaty, C.

    1969-01-01

    The electron spin resonance (E.S.R.) spectra of gamma irradiated polar organic glasses, at 77 K, shows a single line centered at g ∼ 2, attributed to solvated electrons. The radicals produced on scavenging this species by electron acceptors, such as aromatic hydrocarbons, nitro-compounds and azines have been studied by E.S.R. In most cases, the radicals from these solutes, the spectra of which are observed after elimination by warming of the radicals from the matrices, are produced by protonation of the anions formed by scavenging of electrons at 77 K. Thus, in the case of glassy solutions of nitro-compounds, the radicals R NO 2 H are formed. They are characterized by a N = 15 G (nitrobenzene) or a N = 28 G (nitro-alkane). These radicals are also generated by U.V, photolysis at room temperature of solutions of nitro-compounds in alcohols and are shown to be the precursors of nitroxide radicals R - N - R (with N - O) observed simultaneously. Gamma irradiation of solutions of pyridine and of the three diazines, in alcohol glasses at 77 K, produces the radical formed by hydrogen addition to these compounds. The value of the coupling constant of the additional proton (7-10 G) indicates that it is bound to a nitrogen in the sp 2 hydridation state. One has shown, taking pyridine as an example, that the addition to a carbon gives a much greater value of the coupling constant, of the order of 50-60 G. (author) [fr

  3. METAL OXIDE DOPED ANTIBACTERIAL POLYMERIC COATED TEXTILE MATERIALS AND ASSESSEMENT OF ANTIBACTERIAL ACTIVITY WITH ELECTRON SPIN RESONANCE

    Directory of Open Access Journals (Sweden)

    GEDIK Gorkem

    2017-05-01

    Full Text Available Antibacterial activity of a food conveyor belt is an essential property in some cases. However, every antibacterial chemical is not suitable to contact with food materials. Many metal oxides are suitable option for this purpose. The aim of this study was to investigate antibacterial properties of zinc oxide doped PVC polymer coated with electron spin resonance technique. Therefore, optimum zinc oxide containing PVC paste was prepared and applied to textile surface. Coating construction was designed as double layered, first layer did not contain antibacterial agent, thin second layer contained zinc oxide at 10-35% concentration. Oxygen radicals released from zinc oxide containing polymeric coated surface were spin trapped with DMPO (dimethylpyrroline-N-oxide spin trap and measured with Electron Spin Resonance (ESR. Besides conveyor belt samples, oxygen radical release from zinc oxide surface was measured with ESR under UV light and dark conditions. Oxygen radical release was determined even at dark conditions. Antibacterial properties were tested with ISO 22196 standard using Listeria innocua species. Measured antibacterial properties were related with ESR results. Higher concentration of zinc oxide resulted in higher antibacterial efficiency. DCFH-DA flourometric assay was carried out to determine oxidative stress insidebacteria. It is tought that, this technique will lead to decrease on the labour and time needed for conventional antibacterial tests.

  4. Investigating electron spin resonance spectroscopy of a spin-½ compound in a home-built spectrometer

    Science.gov (United States)

    Sarkar, Jit; Roy, Subhadip; Singh, Jitendra Kumar; Singh, Sourabh; Chakraborty, Tanmoy; Mitra, Chiranjib

    2018-05-01

    In this work we report electron spin resonance (ESR) measurements performed on NH4CuPO4.H2O, a Heisenberg spin ½ dimer compound. We carried out the experiments both at room temperature and at 78 K, which are well above the antiferromagnetic ordering temperature of the system where the paramagnetic spins have a dominant role in determining its magnetic behavior. We performed the measurements in a home built custom designed continuous wave electron spin resonance (CW-ESR) spectrometer. By analyzing the experimental data, we were able to quantify the Landé g-factor and the ESR line-width of the sample.

  5. Electron spin resonance (ESR), electron nuclear double resonance (ENDOR) and general triple resonance of irradiated biocarbonates

    International Nuclear Information System (INIS)

    Schramm, D.U.; Rossi, A.M.

    1996-01-01

    Several irradiated bicarbonates were studied by magnetic resonance techniques. Seven paramagnetic species, attributed to CO 2 - , SO 2 - and SO 3 - were identified. Comparison between radiation induced defects in bioaragonites and aragonite single-crystals show that isotropic and orthorhombic CO 2 - centers with broad line spectra are not produced in the latter samples. Vibrational and rotational properties of isotropic CO 2 - centers were studied from low temperature Q-band spectras. Vibrational frequency is determined from the 13 CO 2 - hyperfine spectrum and yielded ν 1.54 x 10 13 s -1 . The correlation time for isotropic CO 2 - , τc) = 1.2 x 10 -11 s (T = 300 K0, is typical of radicals rotating in liquids. ENDOR and General Triple spectroscopy show that orthorhombic CO 2 - centres are surrounded by water molecules located in the second nearest CO 2 2- sites at 5.14, 5.35 and 6.02 A. Water molecules replacing carbonates or as liquid inclusion of growth solution in local crystal imperfections may be responsible for the variety of orthorhombic and isotropic CO 2 - species, respectively. (author)

  6. Continuous wave protocol for simultaneous polarization and optical detection of P1-center electron spin resonance

    Science.gov (United States)

    Kamp, E. J.; Carvajal, B.; Samarth, N.

    2018-01-01

    The ready optical detection and manipulation of bright nitrogen vacancy center spins in diamond plays a key role in contemporary quantum information science and quantum metrology. Other optically dark defects such as substitutional nitrogen atoms (`P1 centers') could also become potentially useful in this context if they could be as easily optically detected and manipulated. We develop a relatively straightforward continuous wave protocol that takes advantage of the dipolar coupling between nitrogen vacancy and P1 centers in type 1b diamond to detect and polarize the dark P1 spins. By combining mutual spin flip transitions with radio frequency driving, we demonstrate the simultaneous optical polarization and detection of the electron spin resonance of the P1 center. This technique should be applicable to detecting and manipulating a broad range of dark spin populations that couple to the nitrogen vacancy center via dipolar fields, allowing for quantum metrology using these spin populations.

  7. Detection of irradiated deboned turkey meat using electron spin resonance spectroscopy

    International Nuclear Information System (INIS)

    Gray, Richard; Stevenson, M.H.

    1989-01-01

    Bone fragments were extracted from two blocks of frozen deboned turkey meat (irradiated and non-irradiated) using alcoholic KOH digestion. Electron spin resonance (ESR) spectroscopy was used to differentiate between the samples. Comparison of an alcoholic KOH digestion procedure with a freeze drying and grinding method showed that the former method gave a signal which was 78% of that obtained using the freeze drying procedure. Regression analysis of the results obtained after subjection of the original non-irradiated sample to irradiation doses of 3.0, 5.0 and 7.0 kGy gave a linear relationship between irradiation dose and ESR signal strength over this range. Using this relationship the estimated mean dose received by the irradiated block was 4.72 kGy. (author)

  8. Electron spin resonance of gamma, electron, neutron and fission fragments irradiated K2SO4

    International Nuclear Information System (INIS)

    Kamali, J.; Walton, G.N.

    1985-01-01

    The electron spin resonance (ESR) of K 2 SO 4 irradiated by γ, electron, neutron and fission fragments has been investigated. The ESR spectra are attributed mainly to the formation of SO 3 - , SO 4 - , SO 2 - , and O 3 - radical ions. The most intense radical ion observed was due to the SO 3 - , and the other radicals were relatively much lower in intensity. Thermal annealing showed a significant decrease in the concentration of radical ions. The concentration of SO 3 - was measured in γ-irradiated K 2 SO 4 and K 2 SO 4 containing fission fragments. In fission fragments irradiated K 2 SO 4 , the G-value observed for SO 3 - radical formation was about eight times higher than that of γ-irradiated K 2 SO 4 . This was attributed to the high LET (Linear Energy Transfer) of the fission fragments. (author)

  9. Electron spin resonance and spin-valley physics in a silicon double quantum dot.

    Science.gov (United States)

    Hao, Xiaojie; Ruskov, Rusko; Xiao, Ming; Tahan, Charles; Jiang, HongWen

    2014-05-14

    Silicon quantum dots are a leading approach for solid-state quantum bits. However, developing this technology is complicated by the multi-valley nature of silicon. Here we observe transport of individual electrons in a silicon CMOS-based double quantum dot under electron spin resonance. An anticrossing of the driven dot energy levels is observed when the Zeeman and valley splittings coincide. A detected anticrossing splitting of 60 MHz is interpreted as a direct measure of spin and valley mixing, facilitated by spin-orbit interaction in the presence of non-ideal interfaces. A lower bound of spin dephasing time of 63 ns is extracted. We also describe a possible experimental evidence of an unconventional spin-valley blockade, despite the assumption of non-ideal interfaces. This understanding of silicon spin-valley physics should enable better control and read-out techniques for the spin qubits in an all CMOS silicon approach.

  10. Detection of organic free radicals in irradiated pepper by electron spin resonance

    International Nuclear Information System (INIS)

    Ukai, Mitsuko; Shimoyama, Yuhei

    2002-01-01

    Using electron spin resonance (ESR) spectroscopy, we revealed various free radicals in a Japanese commercially available black pepper before and after γ-irradiation. The representative ESR spectrum of the pepper is composed of a sextet centered at g=2.0, a singlet at the same g-value and a singlet at g=4.0. The first one is attributable to a signal with hyperfine interactions of Mn 2+ ion (7.4 mT). The second one is due to an organic free radical. The third one may be originated from Fe 3+ ion of the non-hem Fe in proteins. A pair of signals appeared in the black pepper after γ-irradiation. The progressive saturation behavior reconfirmed the signal identification for the radicals in the black pepper. (author)

  11. Evaluation of electron spin resonance technique for the detection of irradiated mango (Mangifera indica L.) fruits

    International Nuclear Information System (INIS)

    Bhushan, B.; Kadam, R.M.; Thomas, P.; Singh, B.B.

    1994-01-01

    The electron spin resonance (ESR) technique was examined as a method for the detection of irradiated mango fruits. A symmetric ESR signal at g = 1.988 was detected in the hard seed cover (endocarp), the dry epidermal layer (testa) surrounding the kernel, and the soft kernel portions of the seed from four mango cultivars. the amplitude of the signal in the epidermal layer and seed cover showed a dose-dependent increase over control values. Qualitatively, however, no new signal was observed following irradiation, except that line width increased by 50%. Methyl cellosolve washing greatly reduced the intensity of the endogenous and radiation (1.0 kGy)-induced ESR signals in the seed cover; results suggest phenolic substances as the source of free radicals. the similarity of naturally occurring ESR signals to that induced by irradiation seems to restrict the practical utility of this method in irradiated mangoes

  12. Singular Value Decomposition Method to Determine Distance Distributions in Pulsed Dipolar Electron Spin Resonance.

    Science.gov (United States)

    Srivastava, Madhur; Freed, Jack H

    2017-11-16

    Regularization is often utilized to elicit the desired physical results from experimental data. The recent development of a denoising procedure yielding about 2 orders of magnitude in improvement in SNR obviates the need for regularization, which achieves a compromise between canceling effects of noise and obtaining an estimate of the desired physical results. We show how singular value decomposition (SVD) can be employed directly on the denoised data, using pulse dipolar electron spin resonance experiments as an example. Such experiments are useful in measuring distances and their distributions, P(r) between spin labels on proteins. In noise-free model cases exact results are obtained, but even a small amount of noise (e.g., SNR = 850 after denoising) corrupts the solution. We develop criteria that precisely determine an optimum approximate solution, which can readily be automated. This method is applicable to any signal that is currently processed with regularization of its SVD analysis.

  13. Field and frequency modulated sub-THz electron spin resonance spectrometer

    Directory of Open Access Journals (Sweden)

    Christian Caspers

    2016-05-01

    Full Text Available 260-GHz radiation is used for a quasi-optical electron spin resonance (ESR spectrometer which features both field and frequency modulation. Free space propagation is used to implement Martin-Puplett interferometry with quasi-optical isolation, mirror beam focusing, and electronic polarization control. Computer-aided design and polarization pathway simulation lead to the design of a compact interferometer, featuring lateral dimensions less than a foot and high mechanical stability, with all components rated for power levels of several Watts suitable for gyrotron radiation. Benchmark results were obtained with ESR standards (BDPA, DPPH using field modulation. Original high-field ESR of 4f electrons in Sm3+-doped Ceria was detected using frequency modulation. Distinct combinations of field and modulation frequency reach a signal-to-noise ratio of 35 dB in spectra of BDPA, corresponding to a detection limit of about 1014 spins.

  14. Electron Spin Resonance Dating of Some Animal Teeth Enamel and Shell Fossils

    International Nuclear Information System (INIS)

    Athabutra, Supakij; Siri-Upathum, Chyagrit

    2007-08-01

    Full text: Electron spin resonance (ESR) dating was conducted for some ungulate tooth enamel samples and shell fossils of the the Tham Lod rock shelter Area I (S23W10) located in Highland Archaeology Project in Pang Mapha District, Mae Hong Son Province, Thailand. Age estimation for wave-induced breaching of the cavity and initial sand deposition (Level 19-29) was 33,200 - 18,700 years and 32,300 years for teeth enamel and the shell fossils of Nodularia scobinata sp. (Carditidae) respectively. ESR spectra showed g-factor g1 (gll, gcenter) = 2.0030 - 2.0036, g2 = 2.0040 - 2.0041 and g3 (g?) = 1.997 - 1.9988 formed by CO2- orthorhombic free radical for teeth enamel and g-factor (gcenter) = 2.0042 + 0.0003 formed by SO3- free radical for fresh shell fossils

  15. Detection of irradiated fruits and vegetables by gas-chromatographic methods and electron spin-resonance

    Energy Technology Data Exchange (ETDEWEB)

    Farag, S.E.A. (National Centre for Radiation Research and Technology, Cairo (Egypt))

    1993-01-01

    Gas chromatographic methods detected some hydrocarbons esp. 17:1, 16:2, 15:0 and 14:1 in irradiated, Avocado, Papaya, Mangoes with 0.75, 1.5, 3.0 kGy and Apricot with 0.5 and 3.0 kGy. The detection of hydrocarbons was clearly at high doses but the low doses need more sensitive conditions using Liquid-Liquid-Gas chromatographic method as used here. Using Electron Spin-Resonance, produce a specific signal from irradiated onion (dried leaves) as well as apricot (hard coat of kernels) after some weeks of irradiation process but not clear with the other foodstuffs. (orig.)

  16. The use of sugar pellets in ESR [electron spin resonance] dosimetry

    International Nuclear Information System (INIS)

    Tchen, A.; Greenstock, C.L.; Trivedi, A.

    1993-01-01

    Table sugar (sucrose) is a convenient, common, tissue-equivalent material suitable for electron spin resonance (ESR) dosimetry of ionising radiation. The simple free radical signal in irradiated sugar is stabilised if the sugar is made into pellets using an inert silicone elastomer (Dow Corning 732). Such pellets, which offer greater convenience and signal stability and reproducibility, have been prepared and tested for their radiation response, sensitivity and post-irradiation stability. Irradiated sugar is detectable at ≥0.1 Gy, the signal intensity is linear with dose, and the fading of the signal, post-irradiation, is minimal for samples kept under ambient conditions. These pellets themselves, given sufficient post-irradiation signal stability, may be useful for environmental monitoring to determine long-term exposures in remote areas or at strategic locations. (Author)

  17. Electron spin resonance of nitrogen-vacancy centers in optically trapped nanodiamonds

    Science.gov (United States)

    Horowitz, Viva R.; Alemán, Benjamín J.; Christle, David J.; Cleland, Andrew N.; Awschalom, David D.

    2012-01-01

    Using an optical tweezers apparatus, we demonstrate three-dimensional control of nanodiamonds in solution with simultaneous readout of ground-state electron-spin resonance (ESR) transitions in an ensemble of diamond nitrogen-vacancy color centers. Despite the motion and random orientation of nitrogen-vacancy centers suspended in the optical trap, we observe distinct peaks in the measured ESR spectra qualitatively similar to the same measurement in bulk. Accounting for the random dynamics, we model the ESR spectra observed in an externally applied magnetic field to enable dc magnetometry in solution. We estimate the dc magnetic field sensitivity based on variations in ESR line shapes to be approximately . This technique may provide a pathway for spin-based magnetic, electric, and thermal sensing in fluidic environments and biophysical systems inaccessible to existing scanning probe techniques. PMID:22869706

  18. Induction-detection electron spin resonance with spin sensitivity of a few tens of spins

    Energy Technology Data Exchange (ETDEWEB)

    Artzi, Yaron; Twig, Ygal; Blank, Aharon [Schulich Faculty of Chemistry Technion—Israel Institute of Technology, Haifa 32000 (Israel)

    2015-02-23

    Electron spin resonance (ESR) is a spectroscopic method that addresses electrons in paramagnetic materials directly through their spin properties. ESR has many applications, ranging from semiconductor characterization to structural biology and even quantum computing. Although it is very powerful and informative, ESR traditionally suffers from low sensitivity, requiring many millions of spins to get a measureable signal with commercial systems using the Faraday induction-detection principle. In view of this disadvantage, significant efforts were made recently to develop alternative detection schemes based, for example, on force, optical, or electrical detection of spins, all of which can reach single electron spin sensitivity. This sensitivity, however, comes at the price of limited applicability and usefulness with regard to real scientific and technological issues facing modern ESR which are currently dealt with conventional induction-detection ESR on a daily basis. Here, we present the most sensitive experimental induction-detection ESR setup and results ever recorded that can detect the signal from just a few tens of spins. They were achieved thanks to the development of an ultra-miniature micrometer-sized microwave resonator that was operated at ∼34 GHz at cryogenic temperatures in conjunction with a unique cryogenically cooled low noise amplifier. The test sample used was isotopically enriched phosphorus-doped silicon, which is of significant relevance to spin-based quantum computing. The sensitivity was experimentally verified with the aid of a unique high-resolution ESR imaging approach. These results represent a paradigm shift with respect to the capabilities and possible applications of induction-detection-based ESR spectroscopy and imaging.

  19. Electron Tunneling in Lithium Ammonia Solutions Probed by Frequency-Dependent Electron-Spin Relaxation Studies

    Science.gov (United States)

    Maeda, Kiminori; Lodge, Matthew T.J.; Harmer, Jeffrey; Freed, Jack H.; Edwards, Peter P.

    2012-01-01

    Electron transfer or quantum tunneling dynamics for excess or solvated electrons in dilute lithium-ammonia solutions have been studied by pulse electron paramagnetic resonance (EPR) spectroscopy at both X- (9.7 GHz) and W-band (94 GHz) frequencies. The electron spin-lattice (T1) and spin-spin (T2) relaxation data indicate an extremely fast transfer or quantum tunneling rate of the solvated electron in these solutions which serves to modulate the hyperfine (Fermi-contact) interaction with nitrogen nuclei in the solvation shells of ammonia molecules surrounding the localized, solvated electron. The donor and acceptor states of the solvated electron in these solutions are the initial and final electron solvation sites found before, and after, the transfer or tunneling process. To interpret and model our electron spin relaxation data from the two observation EPR frequencies requires a consideration of a multi-exponential correlation function. The electron transfer or tunneling process that we monitor through the correlation time of the nitrogen Fermi-contact interaction has a time scale of (1–10)×10−12 s over a temperature range 230–290K in our most dilute solution of lithium in ammonia. Two types of electron-solvent interaction mechanisms are proposed to account for our experimental findings. The dominant electron spin relaxation mechanism results from an electron tunneling process characterized by a variable donor-acceptor distance or range (consistent with such a rapidly fluctuating liquid structure) in which the solvent shell that ultimately accepts the transferring electron is formed from random, thermal fluctuations of the liquid structure in, and around, a natural hole or Bjerrum-like defect vacancy in the liquid. Following transfer and capture of the tunneling electron, further solvent-cage relaxation with a timescale of ca. 10−13 s results in a minor contribution to the electron spin relaxation times. This investigation illustrates the great potential

  20. Electron tunneling in lithium-ammonia solutions probed by frequency-dependent electron spin relaxation studies.

    Science.gov (United States)

    Maeda, Kiminori; Lodge, Matthew T J; Harmer, Jeffrey; Freed, Jack H; Edwards, Peter P

    2012-06-06

    Electron transfer or quantum tunneling dynamics for excess or solvated electrons in dilute lithium-ammonia solutions have been studied by pulse electron paramagnetic resonance (EPR) spectroscopy at both X- (9.7 GHz) and W-band (94 GHz) frequencies. The electron spin-lattice (T(1)) and spin-spin (T(2)) relaxation data indicate an extremely fast transfer or quantum tunneling rate of the solvated electron in these solutions which serves to modulate the hyperfine (Fermi-contact) interaction with nitrogen nuclei in the solvation shells of ammonia molecules surrounding the localized, solvated electron. The donor and acceptor states of the solvated electron in these solutions are the initial and final electron solvation sites found before, and after, the transfer or tunneling process. To interpret and model our electron spin relaxation data from the two observation EPR frequencies requires a consideration of a multiexponential correlation function. The electron transfer or tunneling process that we monitor through the correlation time of the nitrogen Fermi-contact interaction has a time scale of (1-10) × 10(-12) s over a temperature range 230-290 K in our most dilute solution of lithium in ammonia. Two types of electron-solvent interaction mechanisms are proposed to account for our experimental findings. The dominant electron spin relaxation mechanism results from an electron tunneling process characterized by a variable donor-acceptor distance or range (consistent with such a rapidly fluctuating liquid structure) in which the solvent shell that ultimately accepts the transferring electron is formed from random, thermal fluctuations of the liquid structure in, and around, a natural hole or Bjerrum-like defect vacancy in the liquid. Following transfer and capture of the tunneling electron, further solvent-cage relaxation with a time scale of ∼10(-13) s results in a minor contribution to the electron spin relaxation times. This investigation illustrates the great

  1. Spatial profiling of degradation processes in hindered-amine-stabilized polymers by electron spin resonance imaging of nitroxides

    Czech Academy of Sciences Publication Activity Database

    Marek, Antonín; Kaprálková, Ludmila; Pfleger, Jiří; Pospíšil, Jan; Pilař, Jan

    2005-01-01

    Roč. 99, S (2005), s. 195-198 ISSN 0009-2770. [Meeting on Chemistry and Life /3./. Brno, 20.9.2005-22.9.2005] Institutional research plan: CEZ:AV0Z40500505 Keywords : polymer degradation * nitroxides * electron spin resonance imaging Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 0.445, year: 2005

  2. Characterization of lipid oxidation process of beef during repeated freeze-thaw by electron spin resonance technology and Raman spectroscopy.

    Science.gov (United States)

    Chen, Qingmin; Xie, Yunfei; Xi, Jinzhong; Guo, Yahui; Qian, He; Cheng, Yuliang; Chen, Yi; Yao, Weirong

    2018-03-15

    In this study, electron spin resonance (ESR) and Raman spectroscopy were applied to characterize lipid oxidation of beef during repeated freeze-thaw (RFT). Besides the conventional indexes including peroxide values (PV), thiobarbituric acid-reactive substances (TBARS) and acid values (AV) were evaluated, the radical and molecular structure changes were also measured by ESR and Raman spectroscopy. The results showed that PV, TBARS and AV were increased (PRaman intensity of ν(CC) stretching region (1655cm -1 ) was decreased during RFT. Furthermore, lower Raman intensity ratio of I 1655 /I 1442 , I 1655 /I 1745 that determine total unsaturation was also observed. Significant correlations (pRaman spectroscopy. Our result has proved that ESR and Raman spectroscopy showed great potential in characterizing lipid oxidation process of beef during RFT. Copyright © 2017 Elsevier Ltd. All rights reserved.

  3. Electron spin resonance modes in a strong-leg ladder in the Tomonaga-Luttinger liquid phase

    Science.gov (United States)

    Ozerov, M.; Maksymenko, M.; Wosnitza, J.; Honecker, A.; Landee, C. P.; Turnbull, M. M.; Furuya, S. C.; Giamarchi, T.; Zvyagin, S. A.

    2015-12-01

    Magnetic excitations in the strong-leg quantum spin ladder compound (C7H10N) 2CuBr4 (known as DIMPY) in the field-induced Tomonaga-Luttinger spin-liquid phase are studied by means of high-field electron spin resonance (ESR) spectroscopy. The presence of a gapped ESR mode with unusual nonlinear frequency-field dependence is revealed experimentally. Using a combination of analytic and exact-diagonalization methods, we compute the dynamical structure factor and identify this mode with longitudinal excitations in the antisymmetric channel. We argue that these excitations constitute a fingerprint of the spin dynamics in a strong-leg spin-1/2 Heisenberg antiferromagnetic ladder and owe their ESR observability to the uniform Dzyaloshinskii-Moriya interaction.

  4. Characterization of free radicals by electron spin resonance spectroscopy in biochars from pyrolysis at high heating rates and at high temperatures

    DEFF Research Database (Denmark)

    Trubetskaya, Anna; Jensen, Peter Arendt; Jensen, Anker Degn

    2016-01-01

    The concentration and type of free radicals from the decay (termination stage) of pyrolysis at slow and fast heating rates and at high temperatures (above 1000°C) in biomass char have been studied. A room temperature electron spin resonance spectroscopy study was conducted on original wood...... because the free radicals were trapped in a char consisting of a molten amorphous silica at heating rates of 103-104 K s-1. The experimental electron spin resonance spectroscopy spectra were analyzed by fitting to simulated data in order to identify radical types, based on g-values and line widths......, herbaceous biomass, holocelluloses, lignin and their chars, prepared at high temperatures in a wire mesh reactor, an entrained flow reactor, and a tubular reactor. The radical concentrations in the chars from the decay stage range up between 7·1016 and 1.5·1018 spins g -1. The results indicated...

  5. Quantum computers based on electron spins controlled by ultrafast off-resonant single optical pulses.

    Science.gov (United States)

    Clark, Susan M; Fu, Kai-Mei C; Ladd, Thaddeus D; Yamamoto, Yoshihisa

    2007-07-27

    We describe a fast quantum computer based on optically controlled electron spins in charged quantum dots that are coupled to microcavities. This scheme uses broadband optical pulses to rotate electron spins and provide the clock signal to the system. Nonlocal two-qubit gates are performed by phase shifts induced by electron spins on laser pulses propagating along a shared waveguide. Numerical simulations of this scheme demonstrate high-fidelity single-qubit and two-qubit gates with operation times comparable to the inverse Zeeman frequency.

  6. Electron spin resonance in YbRh2Si2: local-moment, unlike-spin and quasiparticle descriptions.

    Science.gov (United States)

    Huber, D L

    2012-06-06

    Electron spin resonance (ESR) in the Kondo lattice compound YbRh(2)Si(2) has stimulated discussion as to whether the low-field resonance outside the Fermi liquid regime in this material is more appropriately characterized as a local-moment phenomenon or one that requires a Landau quasiparticle interpretation. In earlier work, we outlined a collective mode approach to the ESR that involves only the local 4f moments. In this paper, we extend the collective mode approach to a situation where there are two subsystems of unlike spins: the pseudospins of the ground multiplet of the Yb ions and the spins of the itinerant conduction electrons. We assume a weakly anisotropic exchange interaction between the two subsystems. With suitable approximations our expression for the g-factor also reproduces that found in recent unlike-spin quasiparticle calculations. It is pointed out that the success of the local-moment approach in describing the resonance is due to the fact that the susceptibility of the Yb subsystem dominates that of the conduction electrons with the consequence that the relative shift in the resonance frequency predicted by the unlike-spin models (and absent in the local-moment models) is ≪ 1. The connection with theoretical studies of a two-component model with like spins is also discussed.

  7. Detection of irradiation treatment in crustacea by electron spin resonance (ESR) spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Stewart, E.M. [Queen`s Univ., Belfast, Northern Ireland (United Kingdom). Dept. of Food Science; Stevenson, M.H. [Queen`s Univ., Belfast, Northern Ireland (United Kingdom). Dept. of Food Science]|[Department of Agriculture for Northern Ireland, Belfast (United Kingdom); Gray, R. [Department of Agriculture for Northern Ireland, Belfast (United Kingdom)

    1996-12-31

    When the Food (Control of Irradiation) Regulations 1990 came into force in the United Kingdom in January 1991 they included provision for the irradiation of Crustacea to an overall average dose of 3 kGy. The treatment of Crustacea with ionising radiation would reduce numbers of potential pathogens and spoilage organisms thus giving a microbiologically safer product with a longer shelf-life at chill temperatures. At present the process is being used in countries such as France and The Netherlands for the decontamination/shelf-life extension of shrimp. Therefore, as for other food products such as poultry, liquid whole egg and fruit, which are also treated with ionising radiation, it is desirable that a suitable test should be available to help in the control of the irradiation process. One such detection method which has been applied to irradiated Crustacea is that of electron spin resonance (ESR) spectroscopy due to the fact that the rigid exoskeleton has a relatively high dry matter so free radicals produced by ionising irradiation can be trapped and are, therefore, sufficiently stable to be detected. (author).

  8. Detection of irradiation treatment in crustacea by electron spin resonance (ESR) spectroscopy

    International Nuclear Information System (INIS)

    Stewart, E.M.; Gray, R.

    1996-01-01

    When the Food (Control of Irradiation) Regulations 1990 came into force in the United Kingdom in January 1991 they included provision for the irradiation of Crustacea to an overall average dose of 3 kGy. The treatment of Crustacea with ionising radiation would reduce numbers of potential pathogens and spoilage organisms thus giving a microbiologically safer product with a longer shelf-life at chill temperatures. At present the process is being used in countries such as France and The Netherlands for the decontamination/shelf-life extension of shrimp. Therefore, as for other food products such as poultry, liquid whole egg and fruit, which are also treated with ionising radiation, it is desirable that a suitable test should be available to help in the control of the irradiation process. One such detection method which has been applied to irradiated Crustacea is that of electron spin resonance (ESR) spectroscopy due to the fact that the rigid exoskeleton has a relatively high dry matter so free radicals produced by ionising irradiation can be trapped and are, therefore, sufficiently stable to be detected. (author)

  9. Correlation between antioxidant activity and coffee beverage quality by Electron Spin Resonance Spectroscopic

    Directory of Open Access Journals (Sweden)

    Jeam Haroldo Oliveira Barbosa

    2013-12-01

    Full Text Available Brazil is the largest producer of coffee in the world and coffee prices are directly linked to grain quality. In this work, the antioxidant activity of coffee was related to its quality through Electron Spin Resonance Spectroscopy (ESR, as an attempt to establish a non-subjective method to classify the grain quality. For that purpose, the IC50 and temporal monitoring of its non-oxidized fraction were determined for three bean qualities: Soft (High, Hard (Medium and Rio (Low. Methanolic solution of 2,2-difenil-1-picril-hidrazila (DPPH, that has a stable radical and a JEOL FA-200 (X-Band spectrometer were used for these tests. The temporal monitoring of reaction between radical and coffee was performed. The rate of reduced or of antioxidated radicals was determined on time and for each coffee beverage quality were found different slopes of curve: Soft (0.32±0.02, Hard (0.47±0.02 and Rio (0.60±0.02. The IC50 result of Rio quality (2.7 ± 0.9 was different from the Soft (7.8 ± 1.9 and Hard (6.5 ± 1.5 values, but there was no difference between the High and Medium results due to the uncertainty associated. Therefore the results found, mainly for monitoring temporal, establish a new quantitative methodology for classifying the coffee beverage quality.

  10. Electron spin resonance dating of megafauna from Lagoa dos Porcos, Piauí, Brazil.

    Science.gov (United States)

    Kinoshita, Angela; Mayer, Elver; Ribau Mendes, Vinícius; Figueiredo, Ana Maria G; Baffa, Oswaldo

    2014-06-01

    Excavations performed at Lagoa dos Porcos site revealed a vast amount of extinct mammal fossil remains, becoming one of the richest palaeontological occurrences in the Serra da Capivara National Park region, a UNESCO World Heritage. Although anatomic and taxonomic aspects of extinct Quaternary mammals are relatively well known, chronologic information for deposits is rare. In this context, electron spin resonance (ESR) dating of megafauna samples provides important information for establishing a chronological background. This work presents the ESR dating of two teeth, one of Gomphotheriidae and other of Toxodontinae. Dose-response curves of each sample were constructed using spectra acquired with a JEOL FA-200 X-Band spectrometer resulting in equivalent dose (De) of 220 ± 40 Gy and 39 ± 2 Gy for Toxodontinae and Gomphotheriidae tooth, respectively. The conversion of De in age was made using ROSY ESR dating software resulting in 26 ± 4 and 22 ± 3 ka. These results place Lagoa dos Porcos fossil assemblage within the Late Pleistocene. These dates overlap with a period of abrupt increase in rainfall in northeast Brazil, and it is possible that this environmental change is related to the formation of this deposit. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  11. The fate of allogenic radiation sterilized bone grafts controlled by the electron spin resonance spectrometry

    International Nuclear Information System (INIS)

    Ostrowski, K.; Dziedzic-Goclawska, A.

    1981-01-01

    The normal fate of bone grafts is their resorption and substitution by the own host's bone tissue. This phenomenon described as creeping substitution process was controlled using biopsies from the grafted region in allogenic experimental system. Electron spin resonance (ESR) spectrometry was used for independent evaluation of resorption and substitution processes. The measurements were based on the process of induction in the hydroxyapatite (HA) crystals of bone mineral of stable paramagnetic centers which can be detected by ESR spectrometry. The loss of total amount of spins connected with the paramagnetic centers expressed in percent describes the kinetics of resorption. The changes in the concentration of spins due to the ''dilution'' of spins implanted with the graft by the nonirradiated ingrowing host's own bone describe the kinetics of the substitution process. Allogenic bone of calvaria was grafted orthotopically into rabbits after lyophilization and radiation sterilization with a dose of 3.5 Mrads. The process of graft's rebuilding was evaluated using the described ESR method. The application of the described technique in the human clinic is possible. (author)

  12. Electron spin resonance characterization of radical components in irradiated black pepper skin and core

    International Nuclear Information System (INIS)

    Yamaoki, Rumi; Kimura, Shojiro; Ohta, Masatoshi

    2011-01-01

    Characteristics of free radical components of irradiated black pepper fruit (skin) and the pepper seed (core) were analyzed using electron spin resonance. A weak signal near g=2.005 was observed in black pepper before irradiation. Complex spectra near g=2.005 with three lines (the skin) or seven lines (the core) were observed in irradiated black pepper (both end line width; ca. 6.8 mT). The spectral intensities decreased considerably at 30 days after irradiation, and continued to decrease steadily thereafter. The spectra simulated on the basis of the content and the stability of radical components derived from plant constituents, including fiber, starch, polyphenol, mono- and disaccharide, were in good agreement with the observed spectra. Analysis showed that the signal intensities derived from fiber in the skin for an absorbed dose were higher, and the rates of decrease were lower, than that in the core. In particular, the cellulose radical component in the skin was highly stable. - Highlights: → We identified the radical components in irradiated black pepper skin and core. → The ESR spectra near g=2.005 with 3-7 lines were emerged after irradiation. → Spectra simulated basing on the content and the stability of radical from the plant constituents. → Cellulose radical component in black pepper skin was highly stable. → Single signal near g=2.005 was the most stable in black pepper core.

  13. Variability of electron spin resonance (ESR) signal of γ -irradiated starches

    International Nuclear Information System (INIS)

    Silva, Gilberto D.; Rodrigues Junior, Orlando; Mastro, Nelida L. del

    2017-01-01

    Food preservation is one of the practical applications of radiation processing of materials. Starch is an abundant and cheap nutritious biopolymer and also is the material for appropriate food systems and for technical industries. Starch granules are partially crystalline structures composed mainly of two types of starch: amylose, an essentially linear polymer, and amylopectin, with 3-44% of branch points. Electron spin resonance (ESR) spectroscopy is a very powerful and sensitive method for the characterization of the electronic structures of materials with unpaired electrons. The aim of the present work was to monitor the disappearance of the short life and long-life free radicals formed during γ-irradiation of 3 different starches. Corn, potato and fermented cassava starches were irradiated in a "6"0Co source Gammacell 220 with 20 kGy, dose rate around 1 kGy h"-"1. EPR spectra were obtained at room temperature using a Bruker EMX plus model, X band equipment. The main type of ESR signal from irradiated starch is a singlet with a g-value of about 2.0. The fading of ESR signals was followed for 350 hours, and presents differences among the different starch type reflecting differences in molecular arrangements of starch crystalline and amorphous fractions, although ESR spectra seemed to be common for all starches. (author)

  14. Electron Spin Resonance Experiments on a Single Electron in Silicon Implanted with Phosphorous

    Science.gov (United States)

    Luhman, Dwight R.; Nguyen, K.; Tracy, L. A.; Carr, S.; Borchardt, J.; Bishop, N.; Ten Eyck, G.; Pluym, T.; Wendt, J.; Lilly, M. P.; Carroll, M. S.

    2015-03-01

    In this talk we will discuss the results of our ongoing experiments involving electron spin resonance (ESR) on a single electron in a natural silicon sample. The sample consists of an SET, defined by lithographic polysilicon gates, coupled to nearby phosphorous donors. The SET is used to detect charge transitions and readout the spin of the electron being investigated with ESR. The measurements were done with the sample at dilution refrigerator temperatures in the presence of a 1.3 T magnetic field. We will present data demonstrating Rabi oscillations of a single electron in this system as well as measurements of the coherence time, T2. We will also discuss our results using these and various other pulsing schemes in the context of a donor-SET system. This work was performed, in part, at the Center for Integrated Nanotechnologies, a U.S. DOE Office of Basic Energy Sciences user facility. Sandia National Laboratories is a multi-program laboratory operated by Sandia Corporation, a Lockheed-Martin Company, for the U. S. Department of Energy under Contract No. DE-AC04-94AL85000.

  15. Comparison of defects in crystalline oxide semiconductor materials by electron spin resonance

    Energy Technology Data Exchange (ETDEWEB)

    Matsuda, Tokiyoshi, E-mail: toki@rins.ryukoku.ac.jp; Kimura, Mutsumi [Department of Electronics and Informatics, Faculty of Science and Technology, Ryukoku University, 1-438, 1-5 Yokotani, Seta Oe-Cho, Otsu, Shiga 520-2194, Japan and Joint Research Center for Science and Technology, Ryukoku University, 1-5 Yokotani, Seta Oe-Cho, Otsu, Shiga 520-2194 (Japan)

    2015-03-15

    Defects in crystalline InGaZnO{sub 4} (IGZO) induced by plasma were investigated using electron spin resonance (ESR). Thermal stabilities and g factors of two ESR signals (A and B observed at g = 1.939 and 2.003, respectively) in IGZO were different from those of the ESR signals observed in component materials such as Ga{sub 2}O{sub 3} (signal observed at g = 1.969), In{sub 2}O{sub 3} (no signal), and ZnO (signal observed at g = 1.957). Signal A in IGZO increased upon annealing at 300 °C for 1 h, but decreased when annealing was continued for more than 2 h. On the other hand, signal B decreased upon annealing at 300 °C for 1 h. The ESR signal in ZnO decayed in accordance with a second-order decay model with a rate constant of 2.1 × 10{sup −4} s{sup −1}; however, this phenomenon was not observed in other materials. This difference might have been due to randomly formed IGZO lattices such as asymmetrical (Ga, Zn)O and In-O layers. Defects in signals A and B in IGZO were formed in trap states (at the deep level) and tail states, respectively.

  16. Comparison of defects in crystalline oxide semiconductor materials by electron spin resonance

    International Nuclear Information System (INIS)

    Matsuda, Tokiyoshi; Kimura, Mutsumi

    2015-01-01

    Defects in crystalline InGaZnO 4 (IGZO) induced by plasma were investigated using electron spin resonance (ESR). Thermal stabilities and g factors of two ESR signals (A and B observed at g = 1.939 and 2.003, respectively) in IGZO were different from those of the ESR signals observed in component materials such as Ga 2 O 3 (signal observed at g = 1.969), In 2 O 3 (no signal), and ZnO (signal observed at g = 1.957). Signal A in IGZO increased upon annealing at 300 °C for 1 h, but decreased when annealing was continued for more than 2 h. On the other hand, signal B decreased upon annealing at 300 °C for 1 h. The ESR signal in ZnO decayed in accordance with a second-order decay model with a rate constant of 2.1 × 10 −4 s −1 ; however, this phenomenon was not observed in other materials. This difference might have been due to randomly formed IGZO lattices such as asymmetrical (Ga, Zn)O and In-O layers. Defects in signals A and B in IGZO were formed in trap states (at the deep level) and tail states, respectively

  17. Investigation of defects in In–Ga–Zn oxide thin film using electron spin resonance signals

    International Nuclear Information System (INIS)

    Nonaka, Yusuke; Kurosawa, Yoichi; Komatsu, Yoshihiro; Ishihara, Noritaka; Oota, Masashi; Nakashima, Motoki; Hirohashi, Takuya; Takahashi, Masahiro; Yamazaki, Shunpei; Obonai, Toshimitsu; Hosaka, Yasuharu; Koezuka, Junichi; Yamauchi, Jun

    2014-01-01

    In–Ga–Zn oxide (IGZO) is a next-generation semiconductor material seen as an alternative to silicon. Despite the importance of the controllability of characteristics and the reliability of devices, defects in IGZO have not been fully understood. We investigated defects in IGZO thin films using electron spin resonance (ESR) spectroscopy. In as-sputtered IGZO thin films, we observed an ESR signal which had a g-value of g = 2.010, and the signal was found to disappear under thermal treatment. Annealing in a reductive atmosphere, such as N 2 atmosphere, generated an ESR signal with g = 1.932 in IGZO thin films. The temperature dependence of the latter signal suggests that the signal is induced by delocalized unpaired electrons (i.e., conduction electrons). In fact, a comparison between the conductivity and ESR signal intensity revealed that the signal's intensity is related to the number of conduction electrons in the IGZO thin film. The signal's intensity did not increase with oxygen vacancy alone but also with increases in both oxygen vacancy and hydrogen concentration. In addition, first-principle calculation suggests that the conduction electrons in IGZO may be generated by defects that occur when hydrogen atoms are inserted into oxygen vacancies

  18. Investigation of defects in In–Ga–Zn oxide thin film using electron spin resonance signals

    Energy Technology Data Exchange (ETDEWEB)

    Nonaka, Yusuke; Kurosawa, Yoichi; Komatsu, Yoshihiro; Ishihara, Noritaka; Oota, Masashi; Nakashima, Motoki; Hirohashi, Takuya; Takahashi, Masahiro; Yamazaki, Shunpei [Semiconductor Energy Laboratory Co., Ltd., 398 Hase, Atsugi, Kanagawa 243-0036 (Japan); Obonai, Toshimitsu; Hosaka, Yasuharu; Koezuka, Junichi [Advanced Film Device, Inc., 161-2 Masuzuka, Tsuga-machi, Tochigi, Tochigi 328-0114 (Japan); Yamauchi, Jun [Semiconductor Energy Laboratory Co., Ltd., 398 Hase, Atsugi, Kanagawa 243-0036 (Japan); Emeritus Professor of Kyoto University, Oiwake-cho, Kitashirakawa, Kyoto 606-8502 (Japan)

    2014-04-28

    In–Ga–Zn oxide (IGZO) is a next-generation semiconductor material seen as an alternative to silicon. Despite the importance of the controllability of characteristics and the reliability of devices, defects in IGZO have not been fully understood. We investigated defects in IGZO thin films using electron spin resonance (ESR) spectroscopy. In as-sputtered IGZO thin films, we observed an ESR signal which had a g-value of g = 2.010, and the signal was found to disappear under thermal treatment. Annealing in a reductive atmosphere, such as N{sub 2} atmosphere, generated an ESR signal with g = 1.932 in IGZO thin films. The temperature dependence of the latter signal suggests that the signal is induced by delocalized unpaired electrons (i.e., conduction electrons). In fact, a comparison between the conductivity and ESR signal intensity revealed that the signal's intensity is related to the number of conduction electrons in the IGZO thin film. The signal's intensity did not increase with oxygen vacancy alone but also with increases in both oxygen vacancy and hydrogen concentration. In addition, first-principle calculation suggests that the conduction electrons in IGZO may be generated by defects that occur when hydrogen atoms are inserted into oxygen vacancies.

  19. Estimation of the absorbed dose in gamma irradiated food containing bone by electron spin resonance spectroscopy

    International Nuclear Information System (INIS)

    Basfar, A.A.; Abdel Rehim, F.

    1997-01-01

    The use of electron spin resonance (ESR) spectroscopy to accurately evaluate the absorbed dose to radiationprocessed bones (and thus meats) is examined. The exposure of foodstuffs containing bone to a dose of ionizing radiation results in the formation of long lived free radicals which give rise to characteristics ESR signals. The yield of radicals was found to be proportional to absorbed dose. Additive re-irradiation of previously irradiated bone was used to estimate the absorbed dose in the irradiated chicken bone. Simple non-linear rational equation was found to fit to the data and yields good dose estimates for irradiated bone in the range of doses (1.0 - 5.0 kGy). Decay of the ESR signal intensity was monitored at different dose levels (2.0 and 7.0 kGy) up to 22 days. The absorbed dose in irradiated chicken (2.Om 3.0 and 6.0 kGy) was assessed at 2, 6 and 12 days after irradiation. Relatively good results were obtained when measurements were made within the following days (up to 12 days) after irradiation. The ability of the dose additive method to provide accurate dose assessments is tested here

  20. Identification of irradiated wheat by germination test, DNA comet assay and electron spin resonance

    Science.gov (United States)

    Barros, Adilson C.; Freund, Maria Teresa L.; Villavicencio, Ana Lúcia C. H.; Delincée, Henry; Arthur, Valter

    2002-03-01

    In several countries, there has been an increase in the use of radiation for food processing thus improving the quality and sanitary conditions, inhibiting pathogenic microorganisms, delaying the natural aging process and so extending product lifetime. The need to develop analytical methods to detect these irradiated products is also increasing. The goal of this research was to identify wheat irradiated using different radiation doses. Seeds were irradiated with a gamma 60Co source (Gammacell 220 GC) in the Centro de Energia Nuclear na Agricultura and the Instituto de Pesquisas Energéticas e Nucleares. Dose rate used were 1.6 and 5.8kGy/h. Applied doses were 0.0, 0.10, 0.25, 0.50, 0.75, 1.0, and 2.0kGy. After irradiation, seeds were analysed over a 6 month period. Three different detection methods were employed to determine how irradiation had modified the samples. Screening methods consisted of a germination test measuring the inhibition of shooting and rooting and analysis of DNA fragmentation. The method of electron spin resonance spectroscopy allowed a better dosimetric evaluation. These techniques make the identification of irradiated wheat with different doses possible.

  1. Electron spin resonance characterization of trapping centers in Unibond reg-sign buried oxides

    International Nuclear Information System (INIS)

    Conley, J.F. Jr.; Lenahan, P.M.; Wallace, B.D.

    1996-01-01

    Electron spin resonance and capacitance vs. voltage measurements are used to evaluate the radiation response of Unibond buried oxides. When damaged by hole injection, it is found that Unibond reg-sign buried oxides exhibit a rough correspondence between E' centers and positive charge as well as generation of P b centers at the Unibond buried oxide/Si interface. In these respects, Unibond buried oxides qualitatively resemble thermal SiO 2 . However, a hydrogen complexed E' center known as the 74 G doublet is also detected in the Unibond buried oxides. This defect is not detectable in thermal SiO 2 under similar circumstances. Since the presence of 74 G doublet center is generally indicative of very high hydrogen content and since hydrogen is clearly a significant participant in radiation damage, this result suggests a qualitative difference between the radiation response of Unibond and thermal SiO 2 . Unibond results are also compared and contrasted with similar investigations on separation-by-implanted-oxygen (SIMOX) buried oxides. Although the charge trapping response of Unibond buried oxides may be inferior to that of radiation hardened thermal SiO 2 , it appears to be more simple and superior to that of SIMOX buried oxides

  2. Identification of. gamma. -irradiated spices by electron spin resonance (ESR) spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Uchiyama, Sadao; Kawamura, Yoko; Saito, Yukio (National Inst. of Hygienic Sciences, Tokyo (Japan))

    1990-12-01

    The electron spin resonance (ESR) spectrometry spectra of white (WP), black (BP) and red (Capsicum annuum L. var. frutescerns L., RP) peppers each had a principal signal with a g-value of 2.0043, and the intensities of the principal signals were increased not only by {gamma}-irradiation but also by heating. Irradiated RP also showed a minor signal -30G from the principal one, and the intensity of the minor signal increased linearly with increasing dose from 10 to 50 kGy. Since the minor signal was observed in RP irradiated at 10 kGy and stored for one year, but did not appear either after heating or after exposure to this signal is unique to {gamma}-irradiated RP and should therefore be useful for the identification of {gamma}-irradiated spices of Capsicum genus, such as paprika and chili pepper. The computer simulation of the ESR spectra suggested that the minor signal should be assigned to methyl radical and the principal signal mainly to a combination of phenoxyl and peroxyl radicals. Such minor signals were found in {gamma}-irradiated allspice and cinnamon among 10 kinds of other spices. (author).

  3. Identification of γ-irradiated spices by electron spin resonance (ESR) spectrometry

    International Nuclear Information System (INIS)

    Uchiyama, Sadao; Kawamura, Yoko; Saito, Yukio

    1990-01-01

    The electron spin resonance (ESR) spectrometry spectra of white (WP), black (BP) and red (Capsicum annuum L. var. frutescerns L., RP) peppers each had a principal signal with a g-value of 2.0043, and the intensities of the principal signals were increased not only by γ-irradiation but also by heating. Irradiated RP also showed a minor signal -30G from the principal one, and the intensity of the minor signal increased linearly with increasing dose from 10 to 50 kGy. Since the minor signal was observed in RP irradiated at 10 kGy and stored for one year, but did not appear either after heating or after exposure to this signal is unique to γ-irradiated RP and should therefore be useful for the identification of γ-irradiated spices of Capsicum genus, such as paprika and chili pepper. The computer simulation of the ESR spectra suggested that the minor signal should be assigned to methyl radical and the principal signal mainly to a combination of phenoxyl and peroxyl radicals. Such minor signals were found in γ-irradiated allspice and cinnamon among 10 kinds of other spices. (author)

  4. Variability of electron spin resonance (ESR) signal of γ -irradiated starches

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Gilberto D.; Rodrigues Junior, Orlando; Mastro, Nelida L. del, E-mail: nlmastro@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2017-11-01

    Food preservation is one of the practical applications of radiation processing of materials. Starch is an abundant and cheap nutritious biopolymer and also is the material for appropriate food systems and for technical industries. Starch granules are partially crystalline structures composed mainly of two types of starch: amylose, an essentially linear polymer, and amylopectin, with 3-44% of branch points. Electron spin resonance (ESR) spectroscopy is a very powerful and sensitive method for the characterization of the electronic structures of materials with unpaired electrons. The aim of the present work was to monitor the disappearance of the short life and long-life free radicals formed during γ-irradiation of 3 different starches. Corn, potato and fermented cassava starches were irradiated in a {sup 60}Co source Gammacell 220 with 20 kGy, dose rate around 1 kGy h{sup -1}. EPR spectra were obtained at room temperature using a Bruker EMX plus model, X band equipment. The main type of ESR signal from irradiated starch is a singlet with a g-value of about 2.0. The fading of ESR signals was followed for 350 hours, and presents differences among the different starch type reflecting differences in molecular arrangements of starch crystalline and amorphous fractions, although ESR spectra seemed to be common for all starches. (author)

  5. Electron spin resonance and thermoluminescence in powder form of clear fused quartz: effects of grinding

    CERN Document Server

    Ranjbar, A H; Randle, K

    1999-01-01

    Clear fused quartz (CFQ) tubes were powdered either manually by using a mortar and pestle (for coarse production) or mechanically, using a micronising mill (for fine production). A high and multisignal electron spin resonance (ESR) background was found in the fine powder even after annealing it at 900 deg. C for 20 min. In the case of the coarse powder, the signal (ESR background) varied inversely with particle size and was quite high for particle sizes lower than 38 mu m. In a subsidiary experiment, using fine SiO sub 2 powder (99.8% pure, with the particle size of approx 0.007 mu m), manufactured by using flame hydrolysis, only a weak background signal was found. The sup 6 sup 0 Co gamma-ray irradiated powders (approx 22 Gy) were subjected to ESR analysis or thermoluminescence (TL) readout. The ESR intensity of the coarse powder varied directly with particle size. Thus, the intensity for a particle size of 20-38 mu m was very low and almost the same as the unirradiated intensity. In TL readout the results w...

  6. Electron spin resonance dating of mega-fauna from Lagoa dos Porcos, Piaui (Brazil))

    International Nuclear Information System (INIS)

    Kinoshita, Angela; Mayer, Elver; Ribau Mendes, Vinicius; Figueiredo, Ana Maria G.; Baffa, Oswaldo

    2014-01-01

    Excavations performed at Lagoa dos Porcos site revealed a vast amount of extinct mammal fossil remains, becoming one of the richest palaeontological occurrences in the Serra da Capivara National Park region, a UNESCO World Heritage. Although anatomic and taxonomic aspects of extinct Quaternary mammals are relatively well known, chronologic information for deposits is rare. In this context, electron spin resonance (ESR) dating of mega-fauna samples provides important information for establishing a chronological background. This work presents the ESR dating of two teeth, one of Gomphotheriidae and other of Toxodontinae. Dose-response curves of each sample were constructed using spectra acquired with a JEOL FA-200 X-Band spectrometer resulting in equivalent dose (D e ) of 220±40 Gy and 39±2 Gy for Toxodontinae and Gomphotheriidae tooth, respectively. The conversion of D e in age was made using ROSY ESR dating software resulting in 26±4 and 22±3 ka. These results place Lagoa dos Porcos fossil assemblage within the Late Pleistocene. These dates overlap with a period of abrupt increase in rainfall in northeast Brazil, and it is possible that this environmental change is related to the formation of this deposit. (authors)

  7. New Approach For Detection Of Irradiated Spices Using Electron Spin Resonance (ESR)

    International Nuclear Information System (INIS)

    FARAG, S.A.; SHAMS EL DIEEN, N.M.M.

    2010-01-01

    Black pepper and anise samples were irradiated with different doses of gamma rays (5, 10 and 20 kGy) then the irradiated samples were stored at room temperature (20 0 C, 70-75 % RH) for one year. The measurements of free radicals were carried out by electron spin resonance (ESR) at different intervals (3, 6, 9 and 12 months). A series of signals tentatively described as cellulose-like and complex radical observed at G values were 2.01027 for black pepper and 2.01019 for anise. The ESR signals of irradiated spices showed a directly proportional relationship for increasing dose with increasing intensity of signal. A relationship was noticed as polynomial regression analysis resulted between signals of ESR intensity and applied doses with significant values of correlation coefficient (R 2 ). All combination treatments of thermal and irradiation beside long storage caused significant reduction of ESR intensity of irradiated black pepper and anise. Upon using low doses as 1, 2 and 3 kGy for re-irradiation, the irradiated samples (10 and 20 kGy) increased the power of ESR intensity. The enhancement effect was markedly increased. For example, the irradiated black pepper (10 kGy) increased the ESR intensity with high percentages as 49.19%, 69.23% and 89.68% while the high dose (20 kGy) caused increase by 39.96%, 69.05% and 96.90% for irradiated black pepper samples. This approach with that technique can be used easily to overcome the main disadvantages of ESR signals fading especially at the end of storage period.

  8. Electron spin resonance spectroscopy for immunoassay using iron oxide nanoparticles as probe.

    Science.gov (United States)

    Jiang, Jia; Tian, Sizhu; Wang, Kun; Wang, Yang; Zang, Shuang; Yu, Aimin; Zhang, Ziwei

    2018-02-01

    With the help of iron oxide nanoparticles, electron spin resonance spectroscopy (ESR) was applied to immunoassay. Iron oxide nanoparticles were used as the ESR probe in order to achieve an amplification of the signal resulting from the large amount of Fe 3+ ion enclosed in each nanoparticle. Rabbit IgG was used as antigen to test this method. Polyclonal antibody of rabbit IgG was used as antibody to detect the antigen. Iron oxide nanoparticle with a diameter of either 10 or 30 nm was labeled to the antibody, and Fe 3+ in the nanoparticle was probed for ESR signal. The sepharose beads were used as solid phase to which rabbit IgG was conjugated. The nanoparticle-labeled antibody was first added in the sample containing antigen, and the antigen-conjugated sepharose beads were then added into the sample. The nanoparticle-labeled antibody bound to the antigen on sepharose beads was separated from the sample by centrifugation and measured. We found that the detection ranges of the antigen obtained with nanoparticles of different sizes were different because the amount of antibody on nanoparticles of 10 nm was about one order of magnitude higher than that on nanoparticles of 30 nm. When 10 nm nanoparticle was used as probe, the upper limit of detection was 40.00 μg mL -1 , and the analytical sensitivity was 1.81 μg mL -1 . When 30 nm nanoparticle was used, the upper limit of detection was 3.00 μg mL -1 , and the sensitivity was 0.014 and 0.13 μg mL -1 depending on the ratio of nanoparticle to antibody. Graphical abstract Schematic diagram of procedure and ESR spectra.

  9. Electron spin resonance and thermoluminescence in powder form of clear fused quartz: effects of grinding

    International Nuclear Information System (INIS)

    Ranjbar, A.H.; Durrani, S.A.; Randle, K.

    1999-01-01

    Clear fused quartz (CFQ) tubes were powdered either manually by using a mortar and pestle (for coarse production) or mechanically, using a micronising mill (for fine production). A high and multisignal electron spin resonance (ESR) background was found in the fine powder even after annealing it at 900 deg. C for 20 min. In the case of the coarse powder, the signal (ESR background) varied inversely with particle size and was quite high for particle sizes lower than 38 μm. In a subsidiary experiment, using fine SiO 2 powder (99.8% pure, with the particle size of ∼0.007 μm), manufactured by using flame hydrolysis, only a weak background signal was found. The 60 Co gamma-ray irradiated powders (∼22 Gy) were subjected to ESR analysis or thermoluminescence (TL) readout. The ESR intensity of the coarse powder varied directly with particle size. Thus, the intensity for a particle size of 20-38 μm was very low and almost the same as the unirradiated intensity. In TL readout the results were the opposite: the TL intensity of the coarse powder varied inversely with the particle size down to 38 μm, after which it decreased with decreasing particle size of the material. The fine powder, produced by grinding the CFQ tubes, was insensitive to gamma-rays (at least at doses of up to 50 Gy); but for the flame hydrolysis SiO 2 the situation was the opposite. The minimum detectable dose (MDD) for the CFQ in powder form using ESR was ∼2 Gy, which is ∼2 times higher than that for the bulk form, while the MDD for the powder using TL was ∼20 μGy, which is ∼2 times lower than that for the bulk form of the material

  10. Electron spin resonance and thermoluminescence in powder form of clear fused quartz: effects of grinding

    Energy Technology Data Exchange (ETDEWEB)

    Ranjbar, A.H. [Physics Department, Shahid Bahonar University of Kerman, Kerman (Iran, Islamic Republic of); Durrani, S.A. [School of Physics and Space Research, University of Birmingham, Birmingham (United Kingdom); Randle, K. [School of Chemistry, University of Birmingham, Birmingham (United Kingdom)

    1999-02-01

    Clear fused quartz (CFQ) tubes were powdered either manually by using a mortar and pestle (for coarse production) or mechanically, using a micronising mill (for fine production). A high and multisignal electron spin resonance (ESR) background was found in the fine powder even after annealing it at 900 deg. C for 20 min. In the case of the coarse powder, the signal (ESR background) varied inversely with particle size and was quite high for particle sizes lower than 38 {mu}m. In a subsidiary experiment, using fine SiO{sub 2} powder (99.8% pure, with the particle size of {approx}0.007 {mu}m), manufactured by using flame hydrolysis, only a weak background signal was found. The {sup 60}Co gamma-ray irradiated powders ({approx}22 Gy) were subjected to ESR analysis or thermoluminescence (TL) readout. The ESR intensity of the coarse powder varied directly with particle size. Thus, the intensity for a particle size of 20-38 {mu}m was very low and almost the same as the unirradiated intensity. In TL readout the results were the opposite: the TL intensity of the coarse powder varied inversely with the particle size down to 38 {mu}m, after which it decreased with decreasing particle size of the material. The fine powder, produced by grinding the CFQ tubes, was insensitive to gamma-rays (at least at doses of up to 50 Gy); but for the flame hydrolysis SiO{sub 2} the situation was the opposite. The minimum detectable dose (MDD) for the CFQ in powder form using ESR was {approx}2 Gy, which is {approx}2 times higher than that for the bulk form, while the MDD for the powder using TL was {approx}20 {mu}Gy, which is {approx}2 times lower than that for the bulk form of the material.

  11. Strongly driven electron spins using a Ku band stripline electron paramagnetic resonance resonator

    Science.gov (United States)

    Yap, Yung Szen; Yamamoto, Hiroshi; Tabuchi, Yutaka; Negoro, Makoto; Kagawa, Akinori; Kitagawa, Masahiro

    2013-07-01

    This article details our work to obtain strong excitation for electron paramagnetic resonance (EPR) experiments by improving the resonator's efficiency. The advantages and application of strong excitation are discussed. Two 17 GHz transmission-type, stripline resonators were designed, simulated and fabricated. Scattering parameter measurements were carried out and quality factor were measured to be around 160 and 85. Simulation results of the microwave's magnetic field distribution are also presented. To determine the excitation field at the sample, nutation experiments were carried out and power dependence were measured using two organic samples at room temperature. The highest recorded Rabi frequency was rated at 210 MHz with an input power of about 1 W, which corresponds to a π/2 pulse of about 1.2 ns.

  12. Detection of reactive oxygen species in isolated, perfused lungs by electron spin resonance spectroscopy

    Directory of Open Access Journals (Sweden)

    Schudt Christian

    2005-07-01

    Full Text Available Abstract Background The sources and measurement of reactive oxygen species (ROS in intact organs are largely unresolved. This may be related to methodological problems associated with the techniques currently employed for ROS detection. Electron spin resonance (ESR with spin trapping is a specific method for ROS detection, and may address some these technical problems. Methods We have established a protocol for the measurement of intravascular ROS release from isolated buffer-perfused and ventilated rabbit and mouse lungs, combining lung perfusion with the spin probe l-hydroxy-3-carboxy-2,2,5,5-tetramethylpyrrolidine (CPH and ESR spectroscopy. We then employed this technique to characterize hypoxia-dependent ROS release, with specific attention paid to NADPH oxidase-dependent superoxide formation as a possible vasoconstrictor pathway. Results While perfusing lungs with CPH over a range of inspired oxygen concentrations (1–21 %, the rate of CP• formation exhibited an oxygen-dependence, with a minimum at 2.5 % O2. Addition of superoxide dismutase (SOD to the buffer fluid illustrated that a minor proportion of this intravascular ROS leak was attributable to superoxide. Stimulation of the lungs by injection of phorbol-12-myristate-13-acetate (PMA into the pulmonary artery caused a rapid increase in CP• formation, concomitant with pulmonary vasoconstriction. Both the PMA-induced CPH oxidation and the vasoconstrictor response were largely suppressed by SOD. When the PMA challenge was performed at different oxygen concentrations, maximum superoxide liberation and pulmonary vasoconstriction occurred at 5 % O2. Using a NADPH oxidase inhibitor and NADPH-oxidase deficient mice, we illustrated that the PMA-induced superoxide release was attributable to the stimulation of NADPH oxidases. Conclusion The perfusion of isolated lungs with CPH is suitable for detection of intravascular ROS release by ESR spectroscopy. We employed this technique to

  13. Free radical scavenging activities measured by electron spin resonance spectroscopy and B16 cell antiproliferative behaviors of seven plants.

    Science.gov (United States)

    Calliste, C A; Trouillas, P; Allais, D P; Simon, A; Duroux, J L

    2001-07-01

    In an effort to discover new antioxidant natural compounds, seven plants that grow in France (most of them in the Limousin countryside) were screened. Among these plants, was the extensively studied Vitis vinifera as reference. For each plant, sequential percolation was realized with five solvents of increasing polarities (hexane, chloroform, ethyl acetate, methanol, and water). Free radical scavenging activities were examined in different systems using electron spin resonance (ESR) spectroscopy. These assays were based on the stable free radical 1,1-diphenyl-2-picrylhydrazyl (DPPH), the hydroxyl radicals generated by a Fenton reaction, and the superoxide radicals generated by the X/XO system. Antiproliferative behavior was studied on B16 melanoma cells. ESR results showed that three plants (Castanea sativa, Filipendula ulmaria, and Betula pendula) possessed, for the most polar fractions (presence of phenolic compounds), high antioxidant activities in comparison with the Vitis vinifera reference. Gentiana lutea was the only one that presented a hydroxyl scavenging activity for the ethyl acetate and chloroform fractions. The antiproliferative test results showed that the same three plants are the most effective, but for the apolar fractions (chloroform and hexane).

  14. Antioxidant capacity of hesperidin from citrus peel using electron spin resonance and cytotoxic activity against human carcinoma cell lines.

    Science.gov (United States)

    Al-Ashaal, Hanan A; El-Sheltawy, Shakinaz T

    2011-03-01

    Hesperidin is a flavonoid that has various pharmacological activities including anti-inflammatory, antimicrobial and antiviral activities. The aim of the study is the isolation of hesperidin from the peel of Citrus sinensis L. (Rutaceae), and the evaluation of its antioxidant capacity and cytotoxicity against different human carcinoma cell lines. In the present work, hesperidin is identified and confirmed using chromatographic and spectral analysis. To correlate between hesperidin concentration and antioxidant capacity of peel extracts, extraction was carried out using 1% HCl-MeOH, MeOH, alkaline solution, the concentration of hesperidin determined qualitatively and quantitatively using high performance thin layer chromatography (HPTLC), high performance liquid chromatography (HPLC) analysis, in vitro antioxidant capacity of hesperidin and the extracts against free radical diphenylpicrylhydrazyl (DPPH•) performed using an electron spin resonance spectrophotometer (ESR). Cytotoxic assay against larynx, cervix, breast and liver carcinoma cell lines was performed. Hesperidin was found to be moderately active as an antioxidant agent; its capacity reached 36%. In addition, the results revealed that hesperidin exhibited pronounced anticancer activity against the selected cell lines. IC₅₀ were 1.67, 3.33, 4.17, 4.58 µg/mL, respectively. Orange peels are considered to be a cheap source for hesperidin which may be used in the pharmaceutical industry as a natural chemopreventive agent. Hesperidin and orange peel extract could possess antioxidant properties with a wide range of therapeutic applications.

  15. First observation of alkyne radical anions by electron spin resonance spectroscopy: Hexyne/n-hexane mixed crystals

    International Nuclear Information System (INIS)

    Matsuura, K.; Muto, H.

    1991-01-01

    The radical anions of alkynes have been first observed by electron spin resonance spectroscopy following alkene anions previously studied. Hexyne radical anions were formed in 1-, 2-, or 3-hexyne/n--hexane mixed crystals irradiated at 4.2 or 77 K. The characters of the anions were as follows; (a) the α-proton hyperfine coupling is very large (∼4.5 mT for the 1-hexyne anion), (b) the β-proton couplings are very small (∼1.0 mT for C--H β proton with the conformational angle of 0 degree), and (c) the radicals show a negative g shift (2.0014). From these observations, it was found that the anions have a nonlinear(bent) molecule structure in the anticonfiguration (trans C--C≡C--C) with the bend angle ∼60 degree, and that the unpaired electron orbital is approximately composed of the anticombination of the sp 2 hybrid orbitals of the C≡C carbon atoms. A discussion based on complete neglect of differential overlap (CNDO) molecular orbital (MO) calculations was given for the observed negative g shift, which was shown to be characteristic of the alkyne anions which have a high-lying unpaired electron orbital and an antibonding 2p--2p π carbon orbital just above it on the upper energy side

  16. Study of irradiation effects in the silicon carbide cubic polytype by photoluminescence and electron spin resonance spectroscopies; Etude des effets d'irradiation dans le polytype cubique du carbure de silicium par les techniques spectroscopiques de photoluminescence et de resonance paramagnetique electronique

    Energy Technology Data Exchange (ETDEWEB)

    Lefevre, J

    2008-01-15

    This experimental work has consisted in the study of point defects induced by an electronic irradiation in the cubic crystallographic structure of silicon carbide with low temperature photoluminescence and electron spin resonance spectroscopies. The first one of these measurement tools has allowed to estimate the displacement threshold energy in the silicon sub-lattice and then to analyze the thermal stability of the irradiation defects in the low temperature range: (10-300 K) and then in the high temperature range: (300-1400 K). Besides, on the base of a recent theoretical model, this thesis has confirmed the proposition of the isolated silicon antisite for the D1 center whose running beyond the nominal running temperature of fission nuclear reactors (generation IV), for which SiC is in part intended, seems to be particularly problematic. Measurements carried out by ESR under lighting have at last allowed to detect a new defect in its metastable spin state S=1, possibly associated to a silicon interstitial configuration. (O.M.)

  17. Detection of irradiated food: Electron spin resonance measurement of irradiated meat, fish and nuts. Elektronen-Spin-Resonanz-Messungen an bestrahltem Fleisch, Fisch und bestrahlten Nuessen

    Energy Technology Data Exchange (ETDEWEB)

    Linke, B [Fachgebiet Lebensmittelbestrahlung, Bundesgesundheitsamt, Berlin (Germany); Helle, N [Fachgebiet Lebensmittelbestrahlung, Bundesgesundheitsamt, Berlin (Germany); Mager, M [Fachgebiet Lebensmittelbestrahlung, Bundesgesundheitsamt, Berlin (Germany); Schreiber, G A [Fachgebiet Lebensmittelbestrahlung, Bundesgesundheitsamt, Berlin (Germany); Boegl, K W [Fachgebiet Lebensmittelbestrahlung, Bundesgesundheitsamt, Berlin (Germany)

    1993-09-01

    In an intercomparison study organized by the German Federal Health Office (BGA) the use of electron spin resonance (ESR) spectroscopy as a routine method according to paragraph 35 of the German Food Legislation (LMBG) was tested for bone containing meat, fish and nuts (shells). Each participating laboratory examined six chicken, six rainbow trout and four pistachio samples. The examinations were successful, only three samples were not identified correctly and moreover these mistakes were caused by misinterpretation of the ESR spectra. 13 out of 18 participating laboratories used a new routine ESR spectrometer and all samples were identified correctly with this instrument. (orig.)

  18. Electron spin resonance as a high sensitivity technique for environmental magnetism: determination of contamination in carbonate sediments

    Science.gov (United States)

    Crook, Nigel P.; Hoon, Stephen R.; Taylor, Kevin G.; Perry, Chris T.

    2002-05-01

    This study investigates the application of high sensitivity electron spin resonance (ESR) to environmental magnetism in conjunction with the more conventional techniques of magnetic susceptibility, vibrating sample magnetometry (VSM) and chemical compositional analysis. Using these techniques we have studied carbonate sediment samples from Discovery Bay, Jamaica, which has been impacted to varying degrees by a bauxite loading facility. The carbonate sediment samples contain magnetic minerals ranging from moderate to low concentrations. The ESR spectra for all sites essentially contain three components. First, a six-line spectra centred around g = 2 resulting from Mn2+ ions within a carbonate matrix; second a g = 4.3 signal from isolated Fe3+ ions incorporated as impurities within minerals such as gibbsite, kaolinite or quartz; third a ferrimagnetic resonance with a maxima at 230 mT resulting from the ferrimagnetic minerals present within the bauxite contamination. Depending upon the location of the sites within the embayment these signals vary in their relative amplitude in a systematic manner related to the degree of bauxite input. Analysis of the ESR spectral components reveals linear relationships between the amplitude of the Mn2+ and ferrimagnetic signals and total Mn and Fe concentrations. To assist in determining the origin of the ESR signals coral and bauxite reference samples were employed. Coral representative of the matrix of the sediment was taken remote from the bauxite loading facility whilst pure bauxite was collected from nearby mining facilities. We find ESR to be a very sensitive technique particularly appropriate to magnetic analysis of ferri- and para-magnetic components within environmental samples otherwise dominated by diamagnetic (carbonate) minerals. When employing typical sample masses of 200 mg the practical detection limit of ESR to ferri- and para-magnetic minerals within a diamagnetic carbonate matrix is of the order of 1 ppm and 1 ppb

  19. Study of the nature and of the properties of paramagnetic centers observed by electron spin resonance in conjugated polymers; Etude de la nature des propriete des centres paramagnetiques observes par resonance paramagnetique electronique dans les polymeres conjugues

    Energy Technology Data Exchange (ETDEWEB)

    Nechtschein, M [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

    1967-06-15

    Conjugated polymers contain paramagnetic centers. It is established that these centers are free radicals and a model which defines their electronic structure is proposed. The interactions between these centers are studied, notably by dynamic polarisation experiments. Finally it is shown that the centers have catalytic properties. (author) [French] Les polymeres conjugues contiennent des centres paramagnetiques. L'origine radicalaire de ces centres est etablie et un modele precisant leur structure electronique est propose. Les interactions entre ces centres sont etudiees, notamment a l'aide d'experiences de polarisation dynamique. Des proprietes catalytiques sont mises en evidence. (auteur)

  20. Study of the nature and of the properties of paramagnetic centers observed by electron spin resonance in conjugated polymers; Etude de la nature des propriete des centres paramagnetiques observes par resonance paramagnetique electronique dans les polymeres conjugues

    Energy Technology Data Exchange (ETDEWEB)

    Nechtschein, M. [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

    1967-06-15

    Conjugated polymers contain paramagnetic centers. It is established that these centers are free radicals and a model which defines their electronic structure is proposed. The interactions between these centers are studied, notably by dynamic polarisation experiments. Finally it is shown that the centers have catalytic properties. (author) [French] Les polymeres conjugues contiennent des centres paramagnetiques. L'origine radicalaire de ces centres est etablie et un modele precisant leur structure electronique est propose. Les interactions entre ces centres sont etudiees, notamment a l'aide d'experiences de polarisation dynamique. Des proprietes catalytiques sont mises en evidence. (auteur)

  1. Electron spin resonance investigaton of semiconductor materials for application in thin-film silicon solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, Lihong

    2012-07-01

    In the present work, hydrogenated silicon and its alloys silicon carbide and silicon oxide have been investigated using electron spin resonance (ESR). The microstructure of these materials ranges from highly crystalline to amorphous. The correlation between the paramagnetic defects, microstructure, optical and electrical properties has been discussed. Correspondingly, these properties were characterized by the spin density (N{sub S}), g-value and the lineshape of ESR spectra, Infrared (I{sup IR}{sub C}) and/or Raman crystallinity (I{sup RS}{sub C}) as well as optical absorption and electrical dark conductivity ({sigma}{sub D}). 1. As the light absorber, Si layers essentially should have low defect density and good stability against light exposure. The spin density (N{sub S}) measured by ESR is often used as a measure for the paramagnetic defect density (N{sub D}) in the material. However, ESR sample preparation procedures can potentially cause discrepancy between N{sub S} and N{sub D}. Using Mo-foil, Al-foil and ZnO:Al-covered glass as sacrificial substrates, {mu}c-Si:H and a-Si:H films were deposited by plasma-enhanced chemical vapor deposition (PECVD), and ESR powder samples have been prepared with corresponding procedures. Possible preparation-related metastability and instability effects have been investigated in terms of substrate dependence, HCl-etching and atmosphere exposure. A sequence of 'preparation - annealing - air-exposure - annealing' has been designed to investigate the metastability and instability effects. N{sub S} after post-preparation air exposure is higher than in the annealed states, especially for the highly crystalline {mu}c-Si:H material the discrepancy reached one order of magnitude. Low temperature ESR measurements at 40 K indicated that atmospheric exposure leads to a redistribution of the defect states which in turn influence the evaluated N{sub S}. In annealed conditions the samples tend to have lower N{sub S} presumably due

  2. Characterization of x-ray diffraction and electron spin resonance: Effects of sintering time and temperature on bovine hydroxyapatite

    International Nuclear Information System (INIS)

    Kusrini, Eny; Sontang, Muhammad

    2012-01-01

    The physical and chemical properties of a hydroxyapatite produced by the sintering of bovine bone were investigated by powder x-ray diffraction (PXRD), electron spin resonance (ESR), energy dispersive x-ray spectroscopy (EDX), scanning electron microscopy (SEM), Fourier transform infrared (FTIR), and differential thermal analysis (DTA). A bovine bone powder was sintered at different temperatures ranging from 500 to 1400 °C. The influences of post-irradiation storage on the radiation ESR response of the bovine bone powder before and after sintering were also studied. The results indicate that the sintered bovine bone powder contained hydroxyapatite. Diffraction patterns were sharp and clear based on the (211), (300), and (202) reflections corresponding to bovine hydroxyapatite (BHA), which confirmed the phase purity and high crystalline grade of the BHA produced. The PXRD profile of BHA was dependent on sintering temperatures and times. The molecular formula of BHA was determined by Rietveld analysis showed a similar structure and composition to calcium hydroxyapatite in hexagonal P6 3 /m space group a=b=9.435 Å and c=6.895 Å. ESR data showed that the sintering process can decrease the number of free radicals in BHA; it also revealed that the number of free radicals is constant during long storage periods (75 days). The sintering technique described in this study may be used to extract hydroxyapatite from biowaste bovine bone, leading to its application as a bone filler. - Highlights: ► Natural hydroxyapatite was produced from the bio-wasting bovine bones by sintering method. ► PXRD profile of BHA is dependent on the different temperatures and times in sintering process. ► ESR data is useful to study the typical of free radicals formed in the samples after irradiation. ► Stability and physicochemical properties of BHA is dependent on the different storage times. ► Technique is able to be used to find the natural hydroxyapatite applicable for bone filler.

  3. Statistical reexamination of analytical method on the observed electron spin (or nuclear) resonance curves

    International Nuclear Information System (INIS)

    Kim, J.W.

    1980-01-01

    Observed magnetic resonance curves are statistically reexamined. Typical models of resonance lines are Lorentzian and Gaussian distribution functions. In the case of metallic, alloy or intermetallic compound samples, observed resonance lines are supperposed with the absorption line and the dispersion line. The analyzing methods of supperposed resonance lines are demonstrated. (author)

  4. Electron spin resonance analysis of magnetic structures in La2/3Ca1/3MnO3

    International Nuclear Information System (INIS)

    Ding Tao; Zheng Weitao; Zang Jianfeng; Tian Hongwei; Zheng Bing; Wang Xin; Yu Shansheng; Wang Yuming

    2005-01-01

    Measurements of electron spin resonance (ESR) of La 2/3 Ca 1/3 MnO 3 (LCMO) in the ferromagnetic and paramagnetic phases were carried out. Phase transition and temperature dependence of the peak-to-peak ESR linewidth were determined. The transition temperature between ferromagnetic and paramagnetic phases was observed at 265 K. A prominent increase of the peak-to-peak linewidth with decreasing temperature below T c was observed. Using the dynamic scale theory and block spin transformation in critical phenomenon, the quantitative calculation of peak-to-peak linewidth at near T c was made, which was in good agreement with the experimental data. It was believed that the long interactions between the ferromagnetic microregions for LCMO played a key role in determining the ESR linewidth

  5. Novel Electron Spin Resonance-Enzyme Immunosorbent Assay for Detecting Occult Hepatitis B Infection in HCV Chronic Liver Disease

    Directory of Open Access Journals (Sweden)

    Hala Badawi

    2017-11-01

    Full Text Available Background: Hepatitis B virus infection in patients who lack detectable hepatitis B surface antigen (HBsAg is called occult hepatitis B infection (OHB. The very low level of HBV genome may hamper its detection by molecular techniques. Recently, a highly sensitive EIA utilizing a novel modified electron spin resonance (ESR technique (modified ESR-EIA was developed to detect HBsAg by measuring stabilized nitroxide radicals. Aim: to detect occult HBV infection, using ESR-EIA among HCV-related chronic liver disease (CLD Egyptian patients who were seronegative for HBsAg by standard EIA. Methods: The study was conducted on two periods of time; in 1st period, 72 inpatients in Tropical Medicine Department of TBRI, were enrolled in the study. They were divided into two groups; 44 seropositive anti-HCV patients (Group I, 28 seronegative anti-HCV patients (Group II. Sera were subjected to virological assays for HBsAg, HBeAg, anti-HBc IgM, anti-HBc IgG, anti-HBs, anti-HCV and HCV RNA. We also examined serum HBV DNA by polymerase chain reaction (PCR technique and real-time detection polymerase chain reaction (RTD-PCR. In the 2nd period; modified ESR-EIA was applied on 32 TBRI inpatients, 23 in Tropical Medicine Department (Group I and 9 from hemodialysis unit (Group II with HCV-related CLD. Results: OHB was detected in 18.1% and 86.9% of our patients in 2002 and 2006 respectively. In phase 1, there was a higher detection rate among HCV patients in Group I (25% than Group II (7%, with higher prevalence (52.4% in patients with positive HCV RNA in Group I versus those with negative HCV viremia (8% in Group II. HBV DNA by either PCR or RTD-PCR was negative in all patients of both groups as the HBV viral load of the samples were below detectable level of the methods used; less than 100 copies/ml. None of 9 hemodialysis patients were positive for OHB. Conclusion: The newly developed quantitative ESR-EIA technique represents a great evolution for screening and

  6. Electron spin relaxation governed by Raman processes both for Cu2+ ions and carbonate radicals in KHCO3 crystals: EPR and electron spin echo studies

    Science.gov (United States)

    Hoffmann, Stanislaw K.; Goslar, Janina; Lijewski, Stefan

    2012-08-01

    EPR studies of Cu2+ and two free radicals formed by γ-radiation were performed for KHCO3 single crystal at room temperature. From the rotational EPR results we concluded that Cu2+ is chelated by two carbonate molecules in a square planar configuration with spin-Hamiltonian parameters g|| = 2.2349 and A|| = 18.2 mT. Free radicals were identified as neutral HOCOrad with unpaired electron localized on the carbon atom and a radical anion CO3·- with unpaired electron localized on two oxygen atoms. The hyperfine splitting of the EPR lines by an interaction with a single hydrogen atom of HOCOrad was observed with isotropic coupling constants ao = 0.31 mT. Two differently oriented radical sites were identified in the crystal unit cell. Electron spin-lattice relaxation measured by electron spin echo methods shows that both Cu2+ and free radicals relax via two-phonon Raman processes with almost the same relaxation rate. The temperature dependence of the relaxation rate 1/T1 is well described with the effective Debye temperature ΘD = 175 K obtained from a fit to the Debye-type phonon spectrum. We calculated a more realistic Debye temperature value from available elastic constant values of the crystal as ΘD = 246 K. This ΘD-value and the Debye phonon spectrum approximation give a much worse fit to the experimental results. Possible contributions from a local mode or an optical mode are considered and it is suggested that the real phonon spectrum should be used for the relaxation data interpretation. It is unusual that free radicals in KHCO3 relax similarly to the well localized Cu2+ ions, which suggests a small destruction of the host crystal lattice by the ionizing irradiation allowing well coupling between radical and lattice dynamics.

  7. Intercomparisons to evaluate the suitability of gaschromatographic, electron-spin-resonance spectrometric and thermoluminescence methods to detect irradiated foods in routine control

    International Nuclear Information System (INIS)

    Schreiber, G.A.; Helle, N.; Schulzki, G.; Spiegelberg, A.; Linke, B.; Wagner, U.; Boegl, K.W.

    1993-01-01

    The results of four different intercomparisons to detect irradiated fish and chicken meat containing bones, chicken-, pork-, and beef-meat without bones, spices, herbs as well as spice- and herb mixtures, various fruit and vegetables as well as pistachio nuts using gas chromatographic methods, electron-spin resonance spectroscopy or thermoluminescence analyses are reported. (author)

  8. Broadband electron spin resonance in a nanosized La{sub 0.25}Ca{sub 0.75}MnO{sub 3} manganite

    Energy Technology Data Exchange (ETDEWEB)

    Fernàndez-Martínez, Antoni; García-Santiago, Antoni, E-mail: agarciasan@ub.edu; Hernàndez, Joan Manel [Grup de Magnetisme, Departament de Física Fonamental, Facultat de Física, Universitat de Barcelona, Martí i Franquès 1, planta 4, 08028 Barcelona (Spain); Institut de Nanociència i Nanotecnologia IN2UB, Universitat de Barcelona, Martí i Franquès 1, planta 3, edifici nou, 08028 Barcelona (Spain); Zhang, Tao [Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031 (China)

    2014-08-07

    The microwave response of a nanogranular La{sub 0.25}Ca{sub 0.75}MnO{sub 3} manganite has been studied by means of broadband electron spin resonance experiments performed in a commercial magnetic properties measurement system magnetometer using two purpose-built probes. The results concur with the hydrodynamic model for spin-glass systems and allow to determine the gyromagnetic ratio and the effective uniaxial magnetic anisotropy constant in a wide range of temperatures. The thermal behavior of both magnitudes provides information about structural transitions and magnetic interactions within the nanosized grains that make the sample. The experiments enable to corroborate the validity of the applied model in this kind of magnetic systems.

  9. Electron spin resonance insight into broadband absorption of the Cu3Bi(SeO32O2Br metamagnet

    Directory of Open Access Journals (Sweden)

    A. Zorko

    2016-05-01

    Full Text Available Metamagnets, which exhibit a transition from a low-magnetization to a high-magnetization state induced by the applied magnetic field, have recently been highlighted as promising materials for controllable broadband absorption. Here we show results of a multifrequency electron spin resonance (ESR investigation of the Cu3Bi(SeO32O2Br planar metamagnet on the kagome lattice. Its mixed antiferromagnetic/ferromagnetic phase is stabilized in a finite range of applied fields around 0.8 T at low temperatures and is characterized by enhanced microwave absorption. The absorption signal is non-resonant and its boundaries correspond to two critical fields that determine the mixed phase. With decreasing temperature these increase like the sublattice magnetization of the antiferromagnetic phase and show no frequency dependence between 100 and 480 GHz. On the contrary, we find that the critical fields depend on the magnetic-field sweeping direction. In particular, the higher critical field, which corresponds to the transition from the mixed to the ferromagnetic phase, shows a pronounced hysteresis effect, while such a hysteresis is absent for the lower critical field. The observed hysteresis is enhanced at lower temperatures, which suggests that thermal fluctuations play an important role in destabilizing the highly absorbing mixed phase.

  10. Electronic emission and electron spin resonance of irradiated clothes: (cottons, synthetic clothes)

    International Nuclear Information System (INIS)

    El Ajouz Rima, H.

    1984-10-01

    This thesis is devoted to a new method of dosimetry applicable to accidental irradiations. It is based on the use of cotton and synthetic fabric clothes as detectors. It enables absorbed doses and body dose distributions to be estimated after an accidental irradiation. A bibliography on textile fibres used for clothing is presented in the first chapter: origin, structure, industrial treatments, effects of heat, light, ionizing radiations. In the second chapter, electronic emission generated by double stimulation (thermal and optic) is described. This phenomenon reveals changes in the surface state of cotton. Exo-emission was chosen because of its high sensitivity in dosimetry. The third chapter is devoted to the application of electron paramagnetic resonance to the dosimetry of irradiated fabrics. After a brief description of the spectrometer used, the results obtained with commercial cotton fabrics and with a special fabric realized by the Institut Textile de France are described some of these fabrics were subjected to special treatments either before or after irradiation. Synthetic fabrics (polyesters and polypropylene) have also been studied. (author)

  11. Magnetic resonance force microscopy of paramagnetic electron spins at millikelvin temperatures.

    Science.gov (United States)

    Vinante, A; Wijts, G; Usenko, O; Schinkelshoek, L; Oosterkamp, T H

    2011-12-06

    Magnetic resonance force microscopy (MRFM) is a powerful technique to detect a small number of spins that relies on force detection by an ultrasoft magnetically tipped cantilever and selective magnetic resonance manipulation of the spins. MRFM would greatly benefit from ultralow temperature operation, because of lower thermomechanical noise and increased thermal spin polarization. Here we demonstrate MRFM operation at temperatures as low as 30 mK, thanks to a recently developed superconducting quantum interference device (SQUID)-based cantilever detection technique, which avoids cantilever overheating. In our experiment, we detect dangling bond paramagnetic centres on a silicon surface down to millikelvin temperatures. Fluctuations of such defects are supposedly linked to 1/f magnetic noise and decoherence in SQUIDs, as well as in several superconducting and single spin qubits. We find evidence that spin diffusion has a key role in the low-temperature spin dynamics.

  12. Accuracy of dose planning for prostate radiotherapy in the presence of metallic implants evaluated by electron spin resonance dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Alves, G.G. [Departamento de Física, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP (Brazil); Kinoshita, A. [Departamento de Física, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP (Brazil); Universidade Sagrado Coração, Bauru, SP (Brazil); Oliveira, H.F. de; Guimarães, F.S.; Amaral, L.L. [Serviço de Radioterapia, Hospital das Clínicas, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP (Brazil); Baffa, O. [Departamento de Física, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP (Brazil)

    2015-05-26

    Radiotherapy is one of the main approaches to cure prostate cancer, and its success depends on the accuracy of dose planning. A complicating factor is the presence of a metallic prosthesis in the femur and pelvis, which is becoming more common in elderly populations. The goal of this work was to perform dose measurements to check the accuracy of radiotherapy treatment planning under these complicated conditions. To accomplish this, a scale phantom of an adult pelvic region was used with alanine dosimeters inserted in the prostate region. This phantom was irradiated according to the planned treatment under the following three conditions: with two metallic prostheses in the region of the femur head, with only one prosthesis, and without any prostheses. The combined relative standard uncertainty of dose measurement by electron spin resonance (ESR)/alanine was 5.05%, whereas the combined relative standard uncertainty of the applied dose was 3.35%, resulting in a combined relative standard uncertainty of the whole process of 6.06%. The ESR dosimetry indicated that there was no difference (P>0.05, ANOVA) in dosage between the planned dose and treatments. The results are in the range of the planned dose, within the combined relative uncertainty, demonstrating that the treatment-planning system compensates for the effects caused by the presence of femur and hip metal prostheses.

  13. Electron spin resonance of the solvation of radiation-produced silver atoms in alcohol-water mixtures

    International Nuclear Information System (INIS)

    Li, A.S.W.; Kevan, L.

    1982-01-01

    Frozen solutions of silver salts exposed to 60 Co γ-irradiation form silver atoms by reaction of radiation-produced electrons with the silver ion. At 4 K the silver atoms are initially produced in a nonequilibrium or presolvated state and upon brief thermal excitation to 77 K the first solvation shell geometry changes towards an equilibrium or solvated silver atom. This is most pronounced in water but also occurs in methanol, ethanol and n-propanol matrices. The changes in the electron spin resonance magnetic parameters upon silver atom solvation have been determined. In alcohol-water mixtures Ag 0 is preferentially solvated by polycrystalline water at low alcohol concentration. Above a particular alcohol mole percent Ag 0 suddenly changes its environment to a glassy alcohol one. This sudden change occurs at 17, 13 and 6 mol % methanol, ethanol and n-propanol, respectively. These mole percents correlate with the minimum of the excess enthalpy of mixing and with the hydrogen atom trapping ability of these alcohol-water mixtures. The results also suggest that the local environmental disorder around Ag 0 increases with alcohol chain length in alcohol-water frozen solutions. (author)

  14. Accuracy of dose planning for prostate radiotherapy in the presence of metallic implants evaluated by electron spin resonance dosimetry.

    Science.gov (United States)

    Alves, G G; Kinoshita, A; Oliveira, H F de; Guimarães, F S; Amaral, L L; Baffa, O

    2015-07-01

    Radiotherapy is one of the main approaches to cure prostate cancer, and its success depends on the accuracy of dose planning. A complicating factor is the presence of a metallic prosthesis in the femur and pelvis, which is becoming more common in elderly populations. The goal of this work was to perform dose measurements to check the accuracy of radiotherapy treatment planning under these complicated conditions. To accomplish this, a scale phantom of an adult pelvic region was used with alanine dosimeters inserted in the prostate region. This phantom was irradiated according to the planned treatment under the following three conditions: with two metallic prostheses in the region of the femur head, with only one prosthesis, and without any prostheses. The combined relative standard uncertainty of dose measurement by electron spin resonance (ESR)/alanine was 5.05%, whereas the combined relative standard uncertainty of the applied dose was 3.35%, resulting in a combined relative standard uncertainty of the whole process of 6.06%. The ESR dosimetry indicated that there was no difference (P>0.05, ANOVA) in dosage between the planned dose and treatments. The results are in the range of the planned dose, within the combined relative uncertainty, demonstrating that the treatment-planning system compensates for the effects caused by the presence of femur and hip metal prostheses.

  15. Accuracy of dose planning for prostate radiotherapy in the presence of metallic implants evaluated by electron spin resonance dosimetry

    International Nuclear Information System (INIS)

    Alves, G.G.; Kinoshita, A.; Oliveira, H.F. de; Guimarães, F.S.; Amaral, L.L.; Baffa, O.

    2015-01-01

    Radiotherapy is one of the main approaches to cure prostate cancer, and its success depends on the accuracy of dose planning. A complicating factor is the presence of a metallic prosthesis in the femur and pelvis, which is becoming more common in elderly populations. The goal of this work was to perform dose measurements to check the accuracy of radiotherapy treatment planning under these complicated conditions. To accomplish this, a scale phantom of an adult pelvic region was used with alanine dosimeters inserted in the prostate region. This phantom was irradiated according to the planned treatment under the following three conditions: with two metallic prostheses in the region of the femur head, with only one prosthesis, and without any prostheses. The combined relative standard uncertainty of dose measurement by electron spin resonance (ESR)/alanine was 5.05%, whereas the combined relative standard uncertainty of the applied dose was 3.35%, resulting in a combined relative standard uncertainty of the whole process of 6.06%. The ESR dosimetry indicated that there was no difference (P>0.05, ANOVA) in dosage between the planned dose and treatments. The results are in the range of the planned dose, within the combined relative uncertainty, demonstrating that the treatment-planning system compensates for the effects caused by the presence of femur and hip metal prostheses

  16. Technique for magnetic susceptibility determination in the highly doped semiconductors by electron spin resonance

    Energy Technology Data Exchange (ETDEWEB)

    Veinger, A. I.; Zabrodskii, A. G.; Tisnek, T. V.; Goloshchapov, S. I.; Semenikhin, P. V. [Ioffe Institute of the Russian Academy of Sciences, St. Petersburg (Russian Federation)

    2014-08-20

    A method for determining the magnetic susceptibility in the highly doped semiconductors is considered. It is suitable for the semiconductors near the metal - insulator transition when the conductivity changes very quickly with the temperature and the resonance line form distorts. A procedure that is based on double integration of the positive part of the derivative of the absorption line having a Dyson shape and takes into account the depth of the skin layer is described. Analysis is made for the example of arsenic-doped germanium samples at a rather high concentration corresponding to the insulator-metal phase transition.

  17. Laser-excited Fluorescence And Electron-spin Resonance Of Er3+ In Polycrystalline Alcl3

    OpenAIRE

    Ceotto G.; Pires M.A.; Sanjurjo J.A.; Rettori C.; Barberis G.E.

    1990-01-01

    The green fluorescence transitions among the levels corresponding to the 4S3/2 and 4I15/2 configurations of Er3+ diluted in AlCl3 have been measured using laser excitation. The data allow us to determine the crystalline-field splittings of these levels and, in turn, the spin-Hamiltonian parameters. The electron-paramagnetic-resonance spectrum observed at low temperatures is in good agreement with that expected from these parameters. © 1990 The American Physical Society.

  18. Optically detected electron spin-flip resonance in CdMnTe

    International Nuclear Information System (INIS)

    Zeng, S.; Smith, L.C.; Davies, J.J.; Wolverson, D.; Bingham, S.J.; Aliev, G.N.

    2006-01-01

    We show that the spin-flip of electrons at neutral donors in a dilute magnetic semiconductor can be observed directly by means of optically-detected magnetic resonance (ODMR). Spectra obtained at 105 GHz for a bulk crystal of Cd 1-x Mn x Te with x = 0.005 showed strong signals with g -values ranging between 12 (at 4.2 K) and 35 (at 1.7 K), with magnetic resonance linewidths ranging from 0.3 Tesla to 0.1 Tesla at the lowest temperature. In energy terms, these linewidths are independent of temperature and agree with those in spin-flip Raman spectra from the same specimen. The line broadening is caused by fluctuations in the number of manganese ions that interact with a particular donor and an analysis of this leads to a value for the donor Bohr radius of 4.5 nm. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  19. Electron spin resonance of Gd in the nuclear cooling agent: PrNi5 single crystals

    International Nuclear Information System (INIS)

    Levin, R.; Davidov, D.; Grayevsky, A.; Shaltiel, D.; Zevin, V.

    1980-01-01

    The ESR of Gd in single crystals of PrNi 5 is observed to exhibit significant angular dependence of the resonance position and linewidth at low temperatures. This is interpreted in terms of the axial spin Hamiltonian which takes the anisotropic susceptibility and the Gd-Pr exchange into consideration. From lineshape analysis the axial crystal field parameter and isotropic Gd-Pr exchange are derived. The Gd ESR linewidth increases with temperature; the thermal broadening is angularly dependent. This is similar to that observed for the Pr NMR in PrNi 5 single crystals. Both the NMR and ESR thermal broadenings are attributed to low-frequency fluctuations of the Pr ions induced by the Pr-Pr exchange coupling. A model for hexagonal Van-Vleck compounds is given and with the linewidth enables the Pr-Pr exchange coupling, under the assumption of a Gaussian or a Lorenzian distribution of the low-frequency fluctuation spectra, to be extracted. It is suggested that the angular dependence of the ESR thermal broadening is due to the Gd-Pr exchange coupling. (UK)

  20. Radioprotective effects of dimethyl sulfoxide in golden hamster embryo cells exposed to γ-rays at 4 and 77 K as studied by electron spin resonance and biological measurements

    International Nuclear Information System (INIS)

    Miyazaki, T.; Suzuki, K.; Watanabe, M.

    1992-01-01

    Many studies have reported the biological effects of gamma-irradiation on cells. It has been generally accepted that OH radicals produced by radiolysis of water in cells play an important role in the biological effect. OH radicals, however, were not observed directly in these studies. Thus there is some ambiguity in the determination of the reactive species responsible for the biological effect. The effect of dimethyl sulfoxide on gamma-irradiated golden hamster embryo cells has been studied here at 4 and 77 K by direct observation of free radicals and by biological measurements. (author). 2 refs., 4 figs

  1. A Study of the Spin-State Transition and Phase Transformation in [Fe(bpp)(2)][CF(3)SO(3)](2).H(2)O and [Fe(bpp)(2)][BF(4)](2) Using Mn(2+) Electron Spin Resonance.

    Science.gov (United States)

    Sung, Raymond C. W.; McGarvey, Bruce R.

    1999-08-09

    X-band ESR powder studies have been done on the spin transition in Mn(2+)-doped [Fe(bpp)(2)][CF(3)SO(3)](2).H(2)O and [Fe(bpp)(2)][BF(4)](2) (bpp = 2,6-bis(pyrazol-3-yl) pyridine). The change in D value of Mn(2+) during the thermally induced high-spin (HS) low-spin (LS) transition shows that the spin transition is accompanied by a phase transformation involving a domain mechanism. Irradiation experiments at 77 K have shown that a LS --> HS spin change occurs without a change in the crystalline phase. The rate of the change from the HS phase to the LS phase in the vicinity of 100 K has been measured and is found to be the same as that measured for the corresponding spin change obtained from Mössbauer spectroscopy and magnetic susceptibility studies.

  2. Electron spin resonance and E.N.D.O.R. double resonance study of free radicals produced by gamma irradiation of imidazole single crystals; Etude par resonance paramagnetique electronique et double resonance E.N.D.O.R. des radicaux libres crees par irradiation gamma de monocristaux d'imidazole

    Energy Technology Data Exchange (ETDEWEB)

    Lamotte, B [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

    1970-07-01

    Gamma irradiation of imidazole single crystals at 300 deg. K gives two radicals. Identification and detailed studies of their electronic and geometric structure have been made by ESR and ENDOR techniques. A study of the hydrogen bonded protons hyperfine tensor is made and let us conclude to the inexistence of movement and tunneling of these protons. The principal low temperature radical, produced by gamma irradiation at 77 deg. K has been also studied by ESR and a model has been proposed. (author) [French] L'irradiation gamma de monocristaux d'imidazole a 300 deg. K conduit a deux radicaux dont l'identification et l'etude detaillee des structures electroniques et geometriques ont ete obtenues par la resonance paramagnetique electronique (RPE) et la double resonance ENDOR. En particulier l'examen des protons de la liaison hydrogene permet de conclure, pour ceux-ci, a l'inexistence de tout mouvement par effet tunnel. De plus, l'analyse des spectres de RPE du radical principal cree par irradiation gamma de l'imidazole a 77 deg. K nous a permis de proposer un modele pour ce radical. (auteur)

  3. Interaction Study of an Amorphous Solid Dispersion of Cyclosporin A in Poly-Alpha-Cyclodextrin with Model Membranes by 1H-, 2H-, 31P-NMR and Electron Spin Resonance

    Directory of Open Access Journals (Sweden)

    Jean-Claude Debouzy

    2014-01-01

    Full Text Available The properties of an amorphous solid dispersion of cyclosporine A (ASD prepared with the copolymer alpha cyclodextrin (POLYA and cyclosporine A (CYSP were investigated by 1H-NMR in solution and its membrane interactions were studied by 1H-NMR in small unilamellar vesicles and by 31P 2H NMR in phospholipidic dispersions of DMPC (dimyristoylphosphatidylcholine in comparison with those of POLYA and CYSP alone. 1H-NMR chemical shift variations showed that CYSP really interacts with POLYA, with possible adduct formation, dispersion in the solid matrix of the POLYA, and also complex formation. A coarse approach to the latter mechanism was tested using the continuous variations method, indicating an apparent 1 : 1 stoichiometry. Calculations gave an apparent association constant of log Ka = 4.5. A study of the interactions with phospholipidic dispersions of DMPC showed that only limited interactions occurred at the polar head group level (31P. Conversely, by comparison with the expected chain rigidification induced by CYSP, POLYA induced an increase in the fluidity of the layer while ASD formation led to these effects almost being overcome at 298 K. At higher temperature, while the effect of CYSP seems to vanish, a resulting global increase in chain fluidity was found in the presence of ASD.

  4. An electron spin resonance study of bis(tetraphenylarsonium) pentakis(isothiocyanato)nitrosyltechnetate(II): a six-co-ordinate low-spin 4d5 technetium(II) complex

    International Nuclear Information System (INIS)

    Baldas, J.; Boas, J.F.; Bonnyman, J.; Williams, G.A.

    1984-01-01

    The e.s.r. spectrum of the title complex has been studied in non-aqueous solution in the liquid and frozen glass phases. The spectrum is characteristic of a low-spin 4d 5 technetium(II) ion in an axially symmetric environment: g and A values are reported. The small quadrupole interaction observed is solvent dependent. A simple crystal field model, in which the unpaired electron is located in the tsub(2g) orbital triplet, is able to explain most features of the e.s.r. spectrum. A consideration of the electronic parameters derived from the g and A values leads to the conclusion that the results are best explained by a large tetragonal distortion from octahedral symmetry with strong π bonding between technetium and the ligands. (author)

  5. Optical absorption and electron spin resonance studies of Cu in ...

    Indian Academy of Sciences (India)

    Unknown

    Na2O–50B2O3–10As2O3 glasses. In this paper, we report the ESR and optical absorption spectra of Cu2+ ions in xLi2O–(40 – x)Na2O–50B2O3–. 10As2O3 glasses. The values of x were adjusted so that the compositional parameter defined as ...

  6. Electron spin resonance and its implication on the maximum nuclear polarization of deuterated solid target materials

    International Nuclear Information System (INIS)

    Heckmann, J.; Meyer, W.; Radtke, E.; Reicherz, G.; Goertz, S.

    2006-01-01

    ESR spectroscopy is an important tool in polarized solid target material research, since it allows us to study the paramagnetic centers, which are used for the dynamic nuclear polarization (DNP). The polarization behavior of the different target materials is strongly affected by the properties of these centers, which are added to the diamagnetic materials by chemical doping or irradiation. In particular, the ESR linewidth of the paramagnetic centers is a very important parameter, especially concerning the deuterated target materials. In this paper, the results of the first precise ESR measurements of the deuterated target materials at a DNP-relevant magnetic field of 2.5 T are presented. Moreover, these results allowed us to experimentally study the correlation between ESR linewidth and maximum deuteron polarization, as given by the spin-temperature theory

  7. Electron spin resonance in Yb-based Kondo-lattice systems

    International Nuclear Information System (INIS)

    Wykhoff, Jan

    2010-01-01

    The systems Yb 1-w A 1-w (Rh 1-x Co x )(Si 1-y Ge y ) 2 with A=La respectively Lu, as well as YbIr 2 Si 2 are studied. The measurements are presented sortedly for systems, dopings, and external parameters. Beside these external parameters furthermore the orientation of the sample related to the quasistatic magnetic field and the microwave magnetic field was varied.

  8. The use of electron spin resonance spectroscopy for the detection of irradiated shellfish and spices

    International Nuclear Information System (INIS)

    Helle, N.; Linke, B.; Boegl, K.W.; Schreiber, G.A.

    1994-01-01

    A multilateral study on common shrimps, Norway lobster and paprika powder. The use of ESR spectroscopy in shellfish and some types of spice for the detection of previous irradiation is possible even on a routine basis. The radicals producing the specific ESR signals observed could at least in part be identified (CO 2 radicals in shellfish, cellulose radicals in paprica) and the overall rate of correct classifications was seen to be very high for this multicentre study. The multicentre study has further been able to prove that previous reservations about ESR as a method of detection are no longer justified. The authors hold that there is no reason in principle why ESR should not be on the list of officially recommended methods for the examination of shellfish and spices according to paragraph35 LMBG. Nevertheless, the two groups of food at issue here need to be investigated in more detail in a number of further research projects, some of which are mentioned in the following: -investigations on further species of shellfish so as to obtain a broad range of spectra for routine controls; - structural identification of radiation-specific radicals generated in addition to the CO 2 radical; - investigations into the influences of origin, time of fishing and stage of development on the ESR spectra of fishes; - examinations of further spices; - elucidation of links between cellulose contents and radical concentration. (orig./vhe) [de

  9. Optical absorption and electron spin resonance in natural, irradiated and heated spodumene

    International Nuclear Information System (INIS)

    Ito, A.S.; Isotani, S.

    1983-09-01

    Heat treatment and X and γ-Rays irradiation of lylac and colorless natural spodumene, LiAlSi 2 O 6 , have been studied. Irradiation produces a color change, from lylac or colorless to green. Irradiated samples heated at 200 0 C turn lylac and bleach at 400 0 C. Optical absorption spectra were decomposed into gaussian line shape bands and it is observed that green and lylac centers are simultaneously created by irradiation. These centers are independent from each other. Optical absorption, EPR and X-Ray fluorescence results show the spectra of impurities, responsible by the presence of the created centers and indicated Mn participation in the process of centers creation and destruction. Decay Kinetics of green and lylac centers have been studied and it is observed that simple Kinetic models do not apply to these cases. An empirical fit allowed the calculation of activation energies of the lylac and green centers decays. Discussions about the present results led us to propose a new model where the green and lylac centers are due to Mn 3+ ions in two different Al 3+ sites, whose absorption are intensified by the interaction with an electron trapped in a neighbour oxygen. (Author) [pt

  10. Electron spin resonance dating of shells from the sambaqui (shell mound) Capelinha, Sao Paulo, Brazil

    International Nuclear Information System (INIS)

    Kinoshita, A.; Figuty, L.; Baffa, O.

    2006-01-01

    Capelinha is a fluvial sambaqui (Brazilian Shell Mound) located in the Ribeira Valley in the State of Sao Paulo that is being studied. It is one of the oldest sambaquis located along a river dated so far in this region. The use of ESR to date other shells stimulated our group to apply this method to the Capelinha site. Shells from land snails (Megalobulimus sp.) obtained in two levels of excavations were analyzed; one of them was in contact with a skeleton that was dated by C-14. The archaeological doses obtained were (8.05±0.07) Gy and (9.50±0.03) Gy. Since the last site was previously dated by C-14 (Beta -Analytics, Beta 153988) giving: 8860 +/- 60 years BP (conventional age) and 10180 to 9710 years BP (calibrated age), the archaeological dose found for this shell was used to determine the local rate of (0.93 to 0.98) mGy/year, that aggress with other surveys done in the region. Using this dose rate the age of the second shell was found to be 8.14 to 8.73 ky BP that agrees with the stratigraphy of the site. (author)

  11. Effects of finite pulse width on two-dimensional Fourier transform electron spin resonance.

    Science.gov (United States)

    Liang, Zhichun; Crepeau, Richard H; Freed, Jack H

    2005-12-01

    Two-dimensional (2D) Fourier transform ESR techniques, such as 2D-ELDOR, have considerably improved the resolution of ESR in studies of molecular dynamics in complex fluids such as liquid crystals and membrane vesicles and in spin labeled polymers and peptides. A well-developed theory based on the stochastic Liouville equation (SLE) has been successfully employed to analyze these experiments. However, one fundamental assumption has been utilized to simplify the complex analysis, viz. the pulses have been treated as ideal non-selective ones, which therefore provide uniform irradiation of the whole spectrum. In actual experiments, the pulses are of finite width causing deviations from the theoretical predictions, a problem that is exacerbated by experiments performed at higher frequencies. In the present paper we provide a method to deal with the full SLE including the explicit role of the molecular dynamics, the spin Hamiltonian and the radiation field during the pulse. The computations are rendered more manageable by utilizing the Trotter formula, which is adapted to handle this SLE in what we call a "Split Super-Operator" method. Examples are given for different motional regimes, which show how 2D-ELDOR spectra are affected by the finite pulse widths. The theory shows good agreement with 2D-ELDOR experiments performed as a function of pulse width.

  12. Electron spin resonance dating of bones samples from recently excavated in Karnataka, India

    International Nuclear Information System (INIS)

    Ramamurthy, Ramya; Godhandabani, Velraj

    2011-01-01

    The study of radiation defects created in biomaterials, such as bone and teeth, can be used in dating with importance to paleontology and archaeology. A preliminary attempt has been made to date the bone samples from the archaeological site Gudnapur in Karnataka state, India. Each sample was divided into five sets which were given an artificial dose (AD) by using γ rays of 50 Gy, 300 Gy, 800 Gy and 1500 Gy and 3200 Gy. All the samples show similar EPR spectra having g-values 2.0026, 2.0025 and 2.0013 corresponding to CO 2 - orthorhombic and axial CO 2 - respectively. These signals have been used for the age estimation of the archaeological bone samples assuming the dose rate to be 1.12 mGy/a. The calculated ages of the samples are 199 ± 54 ka, 28 ± 23 ka and 225 ± 74 ka. The first and third correspond to the III interglacial stage whereas the second one corresponds to I glacial stage of the Pleistocene epoch respectively and in good agreement with age predicted by archaeological Department. (author)

  13. Electron spin resonance in neutron-irradiated graphite. Dependence on temperature and effect of annealing; Resonance paramagnetique du graphite irradie aux neutrons. Variation en fonction de la temperature et experiences de recuit

    Energy Technology Data Exchange (ETDEWEB)

    Kester, T [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires, Laboratoire de resonance magnetique

    1967-09-01

    The temperature dependence of the electron spin resonance signal from neutron irradiated graphite has been studied. The results lead to an interpretation of the nature of the paramagnetic centers created by irradiation. In annealing experiments on graphite samples, which had been irradiated at low temperature, two annealing peaks and one anti-annealing peak were found. Interpretations are proposed for these peaks. (author) [French] Le graphite irradie aux neutrons a ete etudie par resonance paramagnetique electronique en fonction de la temperature. La nature des centres paramagnetiques crees par irradiation est interpretee a l'aide des resultats. Des experiences de recuit sur des echantillons de graphite irradie a 77 deg. K ont permis de mettre en evidence deux pics de recuit et un pic d'anti-recuit, pour lesquels des interpretations sont proposees. (auteur)

  14. Dating method by electron spin resonance at the 'Museum National d'Histoire Naturelle'. Twenty years of methodological researches and geochronological applications

    International Nuclear Information System (INIS)

    Bahain, J.J.

    2007-12-01

    The Electronic Spin Resonance (ESR) dating method has considerably evolved since its first uses in France at the early 1980's. The samples classically used until the middle part of the 1990's, carbonates and bones, were forsaken progressively and replaced by teeth and bleached quartz. Analytical progresses and methodological developments related to the study of these two materials have considerably increase on one hand the precision and the accuracy of the obtained results, allowing a comparison with those derived from other geochronological techniques, and on the other hand the chronological range of application of the ESR method. Even if the ESR method experiences still today many methodological developments, it has an undeniable geochronological potential and it is one of the rare methods permitting the direct dating of the Lower and Middle Pleistocene layers in non volcanic areas. Then its application is of a considerable importance for the study of the first human settlements of Eurasia and the possibility to date various types of materials carried out from the same archaeological level, jointly by ESR and different other geochronological techniques, by allowing a intercalibration of the results, offers in addition a tool to evaluate the reliability of the obtained ages. Some of the most significant results obtained at the Department of Prehistory of the National Museum of Natural History are evoked in this memory and illustrates both the potential and the current limits of this method. (author)

  15. Direct observation of spin-quadrupolar excitations in Sr2CoGe2O7 by high-field electron spin resonance

    Science.gov (United States)

    Akaki, Mitsuru; Yoshizawa, Daichi; Okutani, Akira; Kida, Takanori; Romhányi, Judit; Penc, Karlo; Hagiwara, Masayuki

    2017-12-01

    Exotic spin-multipolar ordering in spin transition metal insulators has so far eluded unambiguous experimental observation. A less studied, but perhaps more feasible fingerprint of multipole character emerges in the excitation spectrum in the form of quadrupolar transitions. Such multipolar excitations are desirable as they can be manipulated with the use of light or electric field and can be captured by means of conventional experimental techniques. Here we study single crystals of multiferroic Sr2CoGe2O7 and observe a two-magnon spin excitation appearing above the saturation magnetic field in electron spin resonance (ESR) spectra. Our analysis of the selection rules reveals that this spin excitation mode does not couple to the magnetic component of the light, but it is excited by the electric field only, in full agreement with the theoretical calculations. Due to the nearly isotropic nature of Sr2CoGe2O7 , we identify this excitation as a purely spin-quadrupolar two-magnon mode.

  16. Electron spin control of optically levitated nanodiamonds in vacuum.

    Science.gov (United States)

    Hoang, Thai M; Ahn, Jonghoon; Bang, Jaehoon; Li, Tongcang

    2016-07-19

    Electron spins of diamond nitrogen-vacancy (NV) centres are important quantum resources for nanoscale sensing and quantum information. Combining NV spins with levitated optomechanical resonators will provide a hybrid quantum system for novel applications. Here we optically levitate a nanodiamond and demonstrate electron spin control of its built-in NV centres in low vacuum. We observe that the strength of electron spin resonance (ESR) is enhanced when the air pressure is reduced. To better understand this system, we investigate the effects of trap power and measure the absolute internal temperature of levitated nanodiamonds with ESR after calibration of the strain effect. We also observe that oxygen and helium gases have different effects on both the photoluminescence and the ESR contrast of nanodiamond NV centres, indicating potential applications of NV centres in oxygen gas sensing. Our results pave the way towards a levitated spin-optomechanical system for studying macroscopic quantum mechanics.

  17. Electron spin control of optically levitated nanodiamonds in vacuum

    Science.gov (United States)

    Hoang, Thai M.; Ahn, Jonghoon; Bang, Jaehoon; Li, Tongcang

    2016-07-01

    Electron spins of diamond nitrogen-vacancy (NV) centres are important quantum resources for nanoscale sensing and quantum information. Combining NV spins with levitated optomechanical resonators will provide a hybrid quantum system for novel applications. Here we optically levitate a nanodiamond and demonstrate electron spin control of its built-in NV centres in low vacuum. We observe that the strength of electron spin resonance (ESR) is enhanced when the air pressure is reduced. To better understand this system, we investigate the effects of trap power and measure the absolute internal temperature of levitated nanodiamonds with ESR after calibration of the strain effect. We also observe that oxygen and helium gases have different effects on both the photoluminescence and the ESR contrast of nanodiamond NV centres, indicating potential applications of NV centres in oxygen gas sensing. Our results pave the way towards a levitated spin-optomechanical system for studying macroscopic quantum mechanics.

  18. An Endogenous Electron Spin Resonance (ESR signal discriminates nevi from melanomas in human specimens: a step forward in its diagnostic application.

    Directory of Open Access Journals (Sweden)

    Eleonora Cesareo

    Full Text Available Given the specific melanin-associated paramagnetic features, the Electron Spin Resonance (ESR, called also Electron Paramagnetic Resonance, EPR analysis has been proposed as a potential tool for non-invasive melanoma diagnosis. However, studies comparing human melanoma tissues to the most appropriate physiological counterpart (nevi have not been performed, and ESR direct correlation with melanoma clinical features has never been investigated. ESR spectrum was obtained from melanoma and non-melanoma cell-cultures as well as mouse melanoma and non-melanoma tissues and an endogenous ESR signal (g = 2.005 was found in human melanoma cells and in primary melanoma tissues explanted from mice, while it was always absent in non-melanoma samples. These characteristics of the measured ESR signal strongly suggested its connection with melanin. Quantitative analyses were then performed on paraffin-embedded human melanoma and nevus sections, and validated on an independent larger validation set, for a total of 112 sections (52 melanomas, 60 nevi. The ESR signal was significantly higher in melanomas (p = 0.0002 and was significantly different between "Low Breslow's and "High Breslow's" depth melanomas (p<0.0001. A direct correlation between ESR signal and Breslow's depth, expressed in millimetres, was found (R = 0.57; p<0.0001. The eu/pheomelanin ratio was found to be significantly different in melanomas "Low Breslow's" vs melanomas "High Breslow's" depth and in nevi vs melanomas "High Breslow's depth". Finally, ROC analysis using ESR data discriminated melanomas sections from nevi sections with up to 90% accuracy and p<0.0002. In the present study we report for the first time that ESR signal in human paraffin-embedded nevi is significantly lower than signal in human melanomas suggesting that spectrum variations may be related to qualitative melanin differences specifically occurring in melanoma cells. We therefore conclude that this ESR signal

  19. Applications of electron spin resonance to some problems of radiation chemistry; Applications de la resonance paramagnetique electronique a quelques problemes de chimie sous rayonnements

    Energy Technology Data Exchange (ETDEWEB)

    Chachaty, C [Commissariat a l' Energie Atomique Saclay (France). Centre d' Etudes Nucleaires

    1968-06-01

    The electron spin resonance (E.S.R.) spectra of gamma irradiated polar organic glasses, at 77 K, shows a single line centered at g {approx} 2, attributed to solvated electrons. The radicals produced on scavenging this species by electron acceptors, such as aromatic hydrocarbons, nitro-compounds and azines have been studied by E.S.R. In most cases, the radicals from these solutes, the spectra of which are observed after elimination by warming of the radicals from the matrices, are produced by protonation of the anions formed by scavenging of electrons at 77 K. Thus, in the case of glassy solutions of nitro-compounds, the radicals R NO{sub 2}H are formed. They are characterized by a{sub N} = 15 G (nitrobenzene) or a{sub N} = 28 G (nitro-alkane). These radicals are also generated by U.V, photolysis at room temperature of solutions of nitro-compounds in alcohols and are shown to be the precursors of nitroxide radicals R - N - R (with N - O) observed simultaneously. Gamma irradiation of solutions of pyridine and of the three diazines, in alcohol glasses at 77 K, produces the radical formed by hydrogen addition to these compounds. The value of the coupling constant of the additional proton (7-10 G) indicates that it is bound to a nitrogen in the sp{sup 2} hydridation state. One has shown, taking pyridine as an example, that the addition to a carbon gives a much greater value of the coupling constant, of the order of 50-60 G. (author) [French] Les spectres de resonance paramagnetique electronique (R.P.E.) obtenus apres irradiation gamma, a 77 K, de verres organiques polaires tels que les alcools, comportent une bande unique centree a g {approx} 2, attribuable aux electrons solvates. On etudie par R.P.E. les radicaux provenant de leur capture par des solutes ayant une affinite electronique, en particulier les hydrocarbures aromatiques, les composes nitres et les azines. En general, les radicaux provenant de ces solutes, dont on observe les spectres apres elimination

  20. Szilard-Chalmers Processes in Ammonium Dihydrogen Phosphate as Studied by Electrophoresis and Electron Spin Resonance Techniques; Processus Szilard-Chalmers dans le Phosphate d'Ammonium Biacide Etudies par ELectro- Phorese et Resonance de Spin Electronique; 0418 0417 0423 0427 0414 ; Procesos Szilard-Chalmers en el Fosfato Monoamonico Estudiados por Electroforesis y Resonancia del Spin Electronico

    Energy Technology Data Exchange (ETDEWEB)

    Fenger, J.; Nielsen, S. O. [Danish AEC Research Establishment, Riso (Denmark)

    1965-04-15

    Little direct information is available on the defects produced in crystalline phosphates by recoiling hot atoms from the P{sup 31} (n, {gamma})P{sup 32} nuclear reaction, although detailed information is available on the state of P{sup 32} after dissolution of the neutron irradiated crystals. In an attempt to characterize and identify these defects by electron spin resonance (ESR) we report the results of a study, using electrophoresis and ESR techniques, of single crystals of ammonium dihydrogen phosphate after neutron irradiation in a thermal column at temperatures between -196 Degree-Sign C and 40 Degree-Sign C. The ESR spectra were recorded with irradiated single crystals of ND{sub 4}D{sub 2}PO{sub 4}. Four line systems were found. Three of these, constituting the outer part of the spectrum, reduce to doublets in certain orientations of the crystal suggesting a hyperfine coupling to P{sup 31}. No evidence for coupling to P{sup 32} was found. The central part of the spectrum could also be produced by pure y-irradiation. One of the systems of lines in the outer part of the spectrum has been traced to hot atom recoils from the process N{sup 14}(n, p)C{sup 14} and assigned to phosphite radicals that are oriented in eight different ways in the crystal lattice. The results of thermal and radiation annealing as studied by electrophoresis techniques are briefly discussed. The most remarkable finding was that ND{sub 4}D{sub 2}PO{sub 4} and NH{sub 4}H{sub 2}PO{sub 4} after neutron irradiation at 4 Degree-Sign C, -78 Degree-Sign C and -196 Degree-Sign C differed in their retentions which at all three temperatures were about 50% larger in ND{sub 4}D{sub 2}PO{sub 4}. (author) [French] On dispose de peu de renseignements directs sur les defauts induits dans les phosphates cristallins par les atomes chauds de recul provenant de la reaction nucleaire {sup 31}P(n, {gamma}){sup 32}P, alors que l'on possede des donnees precises sur l'etat de {sup 32}P apres dissolution d

  1. Investigations of structure, bonding, and reactions of radiation-induced free radicals in the solid state using electron spin resonance spectroscopy

    International Nuclear Information System (INIS)

    Hudson, R.L.

    1978-01-01

    Electron spin resonance spectroscopy (ESR) has been used to study the structure, bonding, and reactions of several types of free radicals produced by γ irradiation of solids at 77K. Well-defined spectral patterns and the use of photolysis and annealing treatments assisted the analyses and interpretations. The radical anion BF 3 - was generated and identified unequivocally in a matrix of tetramethylsilane at 77K. Both the ESR data and theoretical calculations support a pyramidal structure with a bond angle of about 110 0 . The present experiments showed that BF 3 - has ESR parameters consistent with those of the isoelectronic radicals CF 3 , NF 3 + , and F 2 NO. γ irradiation of polycrystalline trimethyl borate at 77K gave an ESR spectrum which was assigned to the dimer radical anion [(MeO) 3 B.B(OMe) 3 ] - . Radical anions of dialkyl carbonates were observed for the first time and found to undergo a β-scission reaction to produce alkyl radicals. This free radical reaction is unusual in that it proceeds both thermally and photochemically. For the dimethyl carbonate radical anion, 13 C parameters were obtained from a 13 C enriched sample. The photolysis of trapped radicals in γ irradiated carboxylic esters, RC(O)OR', was studied by ESR spectroscopy and two different reactions were characterized. Two hypervalent silicon radical anions were prepared and examined in SI(OCH 3 ) 4 . The results of the present work thus represent the first complete sets of data on the silicon 3s and 3p spin densities for such species. The first PL 3 - radical anion was prepared by the γ irradiation of crystalline trimethylphosphite, and identified through its photolysis reactions and from the results of radiation chemical experiments

  2. Electron spin resonance and its application to heat treated carbonaceous materials; A ressonancia de spin eletronico e sua aplicacao aos materiais carbonosos tratados termicamente

    Energy Technology Data Exchange (ETDEWEB)

    Emmerich, Francisco Guilherme [Espirito Santo Univ., Vitoria, ES (Brazil). Laboratorio de Materiais Carbonosos e Plasma Termico

    1994-12-31

    This work presents the basic characteristics of the electron spin resonance technique, also called paramagnetic resonance, being discussed its application to heat treated carbonaceous materials. In the low heat treatment temperature (HTT) range (below 700 deg C) the organic free radical are the predominant unpaired spin center, which play a key role in the process of carbonization and meso phase formation. At higher temperatures, it is possible to make correlations between the low H T T range and the high HTT range (above 130 deg C), where the predominant unpaired spin center are the free charge carriers (free electrons) of the graphite like crystallites of the material, which are formed by the carbonization process. (author) 10 refs., 3 figs.

  3. Successful combination of electron spin resonance, luminescence and palaeomagnetic dating methods allows reconstruction of the Pleistocene evolution of the lower Moulouya river (NE Morocco)

    Science.gov (United States)

    Bartz, Melanie; Rixhon, Gilles; Duval, Mathieu; King, Georgina E.; Álvarez Posada, Claudia; Parés, Josep M.; Brückner, Helmut

    2018-04-01

    Based on a combination of Electron Spin Resonance (ESR) dating of quartz, luminescence dating of K-feldspar and palaeomagnetism, this study presents the first chronostratigraphic framework for the Pleistocene fluvial deposits of the lower Moulouya river in the Triffa basin (NE Morocco). K-feldspar pIRIR225 and pIRIR290 signals of all samples are saturated, suggesting fluvial deposition at least as early as the Middle Pleistocene (∼0.39-0.80 Ma). Consequently, further chronological information was obtained with ESR dating of quartz grains from the ancient Pleistocene fluvial deposits. As for ESR, the multiple centres approach provides equivalent dose values derived from the Al and Ti centres that mostly agree within 1σ-error, suggesting complete signal resetting from the former during fluvial transport. ESR dating results yield Calabrian deposition ages for all river profiles from ∼1.1 to ∼1.5 Ma. These ages are remarkably consistent with the palaeomagnetic results: the occurrence of mostly reversed polarity in the deposits indicates a Matuyama age (>0.78 Ma). While low incision rates in the Triffa basin (0.025 ± 0.003 mm/a) related to thrusting activity during the Calabrian could be inferred, the fluvial record points to an acyclic and discontinuous sedimentation pattern over the last ∼1.3 Ma. It thereby probably rules out climate as the main driver for fluvial aggradation in the lowermost sedimentary basin. At a regional scale, several indicators point to transient fluvial response resulting from major Quaternary tectonic activity along the Beni Snassen gorge, located directly upstream of the investigated basin. We suggest that a capture event at the margin of the uplifting Beni Snassen massif occurred between 1.04 and 1.36 Ma at the latest and subsequently led to the creation of the gorge.

  4. The challenge of dating Early Pleistocene fossil teeth by the combined uranium series-electron spin resonance method: the Venta Micena palaeontological site (Orce, Spain)

    International Nuclear Information System (INIS)

    Duval, M.; Falgueres, Ch.; Bahain, J.J.; Shao, Q.; Grun, R.; Aubert, M.; Hellstrom, J.; Dolo, J.M.; Agusti, J.; Martinez-Navarro, B.; Palmqvist, P.; Toro-Moyano, I.

    2011-01-01

    The palaeontological site of Venta Micena (Orce, Andalusia, Spain) lies in the eastern sector of the Guadix-Baza basin, one of the best documented areas in Europe for Plio-Pleistocene bio-stratigraphy. The combination of bio-chronological and palaeo-magnetic results, combined with the radiometric data obtained for Atapuerca Sima del Elefante, indicated that the Venta Micena stratum was formed between the Jaramillo and Olduvai palaeo-magnetic events, most likely between 1.22 and 1.77 Ma. Five fossil teeth from two outcrops (sites A and B) were selected to assess the potential of combined uranium series-electron spin resonance (US-ESR) dating of Early Pleistocene sites. Although the US-ESR results of the first outcrop showed a large scatter between the three teeth, the mean age of 1.37 ± 0.24 Ma can be considered a reasonable age estimate for Venta Micena. The mean ESR age of 0.62 ± 0.03 Ma obtained for site B seems to be a severe underestimation when compared with the independent age control. This underestimation is attributed to a relative recent U-mobilization event that led to some U-leaching. The results show that any ESR age calculations of old samples are extremely sensitive to variations in the measured 230 Th/ 234 U ratios in dental tissues. Although the results demonstrate that ESR can in principle be applied to Early Pleistocene sites, they also reveal the complexity of dating such old teeth. It is necessary to continue research in several directions, such as study of the behaviour of ESR signals in old teeth and understanding recent U-mobilization processes, to improve the reliability of the combined US-ESR dating method applied to Early Pleistocene times, a period for which the number of available numerical dating techniques is very limited. (authors)

  5. Structural damage in thin SLIM-Cut c-Si foils fabricated for solar cell purposes: atomic assessment by electron spin resonance

    International Nuclear Information System (INIS)

    Kepa, J; Stesmans, A; Martini, R

    2015-01-01

    Within the context of reducing production costs, thin (<90 μm) silicon foils intended for photovoltaic applications have been fabricated from standard (100)Si wafers using a low-temperature (<150 °C) stress-induced lift-off process. A multi-frequency electron spin resonance (ESR) study was performed in order to evaluate, at atomic scale, the quality of the material in terms of defects, including identification and quantification. Generally, a complex ESR spectrum is observed, disentangled as the superposition of three separate signals. This includes, most prominently (∼91% of total density) the D-line (Si 3  ≡ Si· dangling bonds in a disordered Si environment), a set (∼6%) of highly anisotropic signals ascribed to dislocations (K1-like), and a triplet, identified as the Si-SL5 N-donor defect. Defect density depth profiling from the lift-off side shows all signals disappear in tandem after etching off a ∼33 μm thick Si layer, indicating a highly correlated−equal in relative terms−distribution of the three types of defects over the affected top part of the Si foil. The defect density is found to be highly non-uniform laterally, with the density peaking near the crack initiation point, from which defect generation spreads. It is thus found that the SLIM-Cut method for fabrication of thin Si foils results in the introduction of defects that would unacceptably impair the functionality of photovoltaic cells built on these substrates. Fortunately, this may be cured by etching off a thin top Si layer, resulting in a most useful thin Si foil of standard high quality. (paper)

  6. Electron spin echo study of the E'-center phase relaxation in γ-irradiated quartz glass

    International Nuclear Information System (INIS)

    Dudkin, V.I.; Petrun'kin, V.Yu.; Rubinov, S.V.; Uspenskij, L.I.

    1986-01-01

    Experimental studies of phase relaxation of E'-centres in γ-irradiated quartz glass are conducted by the method of electron spin echo (ESE) for different concentrations of paramagnetic centres. Contribution of mechanisms of spectral and prompt diffusion to kinetics of amplitude drop of echo signal is proved to reduce with growth of delay time between exciting microwave pulse that results in increase of phase memory time at large delays. The mentioned property can be used in electric controlled delay lines on the base of ESE

  7. Decay of organic free radicals in γ-ray irradiated pepper during thermal treatment as detected by electron spin resonance spectroscopy

    International Nuclear Information System (INIS)

    Ukai, Mitsuko; Shimoyama, Yuhei

    2004-01-01

    Using electron spin resonance (ESR) spectroscopy we analysed the thermal decay process of radicals in γ-Irradiated pepper Upon irradiation, the satellite signals were newly induced and appeared at the symmetric positions of the organic free radical, i.e., the g=2.0 signal. Heat treatment decreased the satellite signals exponentially. The ESR signal of the pepper heated for more than 10 min was essentially the same as that before irradiation. To evaluate the radical decay by heat-treatment, we formulated a time-dependent master equation. We could evaluate the time constant of the radical decay based upon the general solution of the equation together with the nonlinear least-squares method

  8. Observing electron spin resonance between 0.1 and 67 GHz at temperatures between 50 mK and 300 K using broadband metallic coplanar waveguides

    Science.gov (United States)

    Wiemann, Yvonne; Simmendinger, Julian; Clauss, Conrad; Bogani, Lapo; Bothner, Daniel; Koelle, Dieter; Kleiner, Reinhold; Dressel, Martin; Scheffler, Marc

    2015-05-01

    We describe a fully broadband approach for electron spin resonance (ESR) experiments, where it is possible to tune not only the magnetic field but also the frequency continuously over wide ranges. Here, a metallic coplanar transmission line acts as compact and versatile microwave probe that can easily be implemented in different cryogenic setups. We perform ESR measurements at frequencies between 0.1 and 67 GHz and at temperatures between 50 mK and room temperature. Three different types of samples (Cr3+ ions in ruby, organic radicals of the nitronyl-nitroxide family, and the doped semiconductor Si:P) represent different possible fields of application for the technique. We demonstrate that an extremely large phase space in temperature, magnetic field, and frequency for ESR measurements, substantially exceeding the range of conventional ESR setups, is accessible with metallic coplanar lines.

  9. Superlattice structure of Ce{sup 3+}-doped BaMgF{sub 4} fluoride crystals - x-ray diffraction, electron spin-resonance, and optical investigations

    Energy Technology Data Exchange (ETDEWEB)

    Yamaga, M.; Hattori, K. [Department of Electrical and Electronic Engineering, Faculty of Engineering, Gifu University, Gifu (Japan); Kodama, N. [Department of Materials Science and Engineering, Faculty of Engineering and Resource Science, Akita University, Akita (Japan); Ishizawa, N. [Materials and Structures Laboratory, Tokyo Institute of Technology, Yokohama (Japan); Honda, M. [Faculty of Science, Naruto University of Education, Naruto (Japan); Shimamura, K.; Fukuda, T. [Institute for Materials Research, Tohoku University, Sendai (Japan)

    2001-09-14

    The x-ray diffraction patterns for Ce{sup 3+}-doped BaMgF{sub 4} (BMF) crystals suggest the existence of superlattice structure. The superlattice model is consistent with the characterization of the 4f{sup 1} ground state of Ce{sup 3+} as a probe ion using the electron spin-resonance (ESR) technique. The distinct Ce{sup 3+} luminescence spectra with different peak energies and lifetimes also support the superlattice model. Although the detailed superlattice structure could not be analysed using the diffraction spots, a model has been proposed, taking into account the eight Ce{sup 3+} polyhedra with different anion coordinations in the unit cell of the BMF crystal obtained from the ESR experiments. (author)

  10. Transient nutation electron spin resonance spectroscopy on spin-correlated radical pairs: A theoretical analysis on hyperfine-induced nuclear modulations

    Science.gov (United States)

    Weber, Stefan; Kothe, Gerd; Norris, James R.

    1997-04-01

    The influence of anisotropic hyperfine interaction on transient nutation electron paramagnetic resonance (EPR) of light-induced spin-correlated radical pairs is studied theoretically using the density operator formalism. Analytical expressions for the time evolution of the transient EPR signal during selective microwave excitation of single transitions are derived for a model system comprised of a weakly coupled radical pair and one hyperfine-coupled nucleus with I=1/2. Zero-quantum electron coherence and single-quantum nuclear coherence are created as a result of the sudden light-induced generation of the radical pair state from a singlet-state precursor. Depending on the relative sizes of the nuclear Zeeman frequency and the secular and pseudo-secular parts of the hyperfine coupling, transitions between levels with different nuclear spin orientations are predicted to modulate the time-dependent EPR signal. These modulations are in addition to the well-known transient nutations and electron zero-quantum precessions. Our calculations provide insight into the mechanism of recent experimental observations of coherent nuclear modulations in the time-resolved EPR signals of doublets and radical pairs. Two distinct mechanisms of the modulations are presented for various microwave magnetic field strengths. The first modulation scheme arises from electron and nuclear coherences initiated by the laser excitation pulse and is "read out" by the weak microwave magnetic field. While the relative modulation depth of these oscillations with respect to the signal intensity is independent of the Rabi frequency, ω1, the frequencies of this coherence phenomenon are modulated by the effective microwave amplitude and determined by the nuclear Zeeman interaction and hyperfine coupling constants as well as the electron-electron spin exchange and dipolar interactions between the two radical pair halves. In a second mechanism the modulations are both created and detected by the microwave

  11. Electron spin echo studies of the internal motion of radicals in crystals: Phase memory vs correlation time

    International Nuclear Information System (INIS)

    Kispert, L.D.; Bowman, M.K.; Norris, J.R.; Brown, M.S.

    1982-01-01

    An electron spin echo (ESE) study of the internal motion of the CH 2 protons in irradiated zinc acetate dihydrate crystals shows that quantitative measurements of the motional correlation time can be obtained quite directly from pulsed measurements. In the slow motional limit, the motional correlation time is equal to the phase memory time determined by ESE. In the fast motional limit, the motional correlation time is proportional to the no motion spectral second moment divided by the ESE phase memory time. ESE offers a convenient method of studying motion, electron transfer, conductivity, etc. in a variety of systems too complicated for study by ordinary EPR. New systems for study by ESE include biological samples, organic polymers, liquid solutions of radicals with unresolved hyperfine, etc. When motion modulates large anisotropic hyperfine couplings, ESE measurements of the phase memory time are sensitive to modulation of pseudosecular hyperfine interactions

  12. Electron spin resonance insight into broadband absorption of the Cu3Bi(SeO3)2O2Br metamagnet

    Science.gov (United States)

    Zorko, A.; Gomilšek, M.; Pregelj, M.; Ozerov, M.; Zvyagin, S. A.; Ozarowski, A.; Tsurkan, V.; Loidl, A.; Zaharko, O.

    2016-05-01

    Metamagnets, which exhibit a transition from a low-magnetization to a high-magnetization state induced by the applied magnetic field, have recently been highlighted as promising materials for controllable broadband absorption. Here we show results of a multifrequency electron spin resonance (ESR) investigation of the Cu3Bi(SeO3)2O2Br planar metamagnet on the kagome lattice. Its mixed antiferromagnetic/ferromagnetic phase is stabilized in a finite range of applied fields around 0.8 T at low temperatures and is characterized by enhanced microwave absorption. The absorption signal is non-resonant and its boundaries correspond to two critical fields that determine the mixed phase. With decreasing temperature these increase like the sublattice magnetization of the antiferromagnetic phase and show no frequency dependence between 100 and 480 GHz. On the contrary, we find that the critical fields depend on the magnetic-field sweeping direction. In particular, the higher critical field, which corresponds to the transition from the mixed to the ferromagnetic phase, shows a pronounced hysteresis effect, while such a hysteresis is absent for the lower critical field. The observed hysteresis is enhanced at lower temperatures, which suggests that thermal fluctuations play an important role in destabilizing the highly absorbing mixed phase.

  13. Microresonators for electron spin qubits

    International Nuclear Information System (INIS)

    Suter, D.; Stonies, R.; Voges, E.

    2005-01-01

    Full text: The traditional high-Q EPR resonators are optimized for large samples. For small samples and individual qubits, it is possible to design different resonators that have much better power handling properties, create less interference with other peripheral lines and, if they are used for detection, have better sensitivity. Other parameters being equal, the sensitivity of the resonator can be increased by minimizing its size and thus increasing the filling factor. In contrast to cavity type resonators, microcoils can be made much smaller than the operation wavelength. For this type of resonator, it has been established theoretically and experimentally that the sensitivity varies inversely with its linear dimensions. Moreover, the planar coil geometry is ideal to be manufactured in a small size by means of standard microtechnology. It also offers advantages for the excitation of electron spins in prototype quantum computer systems. High microwave power to the magnetic field conversion factor of the microresonator allows to achieve 24 ns L/2 - pulses with less than 20 mW of incident power. Within the QIPDDF-ROSES project, we are using such resonators to measure the EPR parameters of monolayer molecular films of N at C60 and for excitation of the single electron spin in a defect center in diamond. The microresonator prototypes consisting of a 200 μm planar microcoil tuned and matched at 14 GHz with distributed elements have been fabricated on Si substrate. The sensitivity tests with a DPPH samples resulted in the sensitivity value 10E9 spins/G/Hz1/2 at 300 K. The designed layouts of the microresonator can be scaled down up to a tens of micrometers, and with a different microwave coupling approach hundreds of nanometers could be achieved, allowing the operation frequency up to 100 THz (author)

  14. Electron Spin Resonance in CuSO45H2O down to 100 mK

    Science.gov (United States)

    Kadowaki, Kazuo; Chiba, Yoshiaki; Kindo, Koichi; Date, Muneyuki

    1988-12-01

    Copper sulfate pentahydrate CuSO45H2O is investigated by ESR at 9, 17, 24, 35 and 50 GHz regions down to about 100 mK using a combined cryostat of 3He and adiabatic demagnetization. The temperature dependent exchange interaction JAB between inequivalent site spins A and B is found. It is about 0.11 K at room temperature and increases with decreasing temperature up to 0.24 K. Temperature dependent resonance shifts are attributed to the exchange shift coming from non-resonant dissimilar spins. Partial order effect below 1 K is discussed.

  15. Characterization and Identification of Gamma-Irradiated Kimchi Cabbage and Broccoli by Electron Spin Resonance Spectroscopy using Different Sample Pre-treatments

    International Nuclear Information System (INIS)

    Kwak, J.Y.; Ahn, J.J.; Kashif Akram; Kim, G.R.; Kwon, J.H.

    2012-01-01

    Electron spin resonance (ESR) spectroscopy of gamma-irradiated fresh broccoli and kimchi cabbage was conducted to identify their irradiation history. Different pretreatments, such as freeze-drying (FD), oven-drying (OD), alcoholic-drying (ALD), and water-washing and alcoholic-drying (WAD) were used to lower the moisture contents of the samples prior to ESR analysis. The non-irradiated samples exhibited a single central signal (g 0 = 2.0007) with clear effect of Mn 2+ , especially in kimchi cabbage. Upon irradiation, there was an increase in the intensity of the central signal, and two side peaks, mutually spaced at 6 mT, were also observed. These side peaks with g 1 (left) = 2.023 and g 2 (right) = 1.985 were attributed to radiation-induced cellulose radicals. Leaf and stem in broccoli, and root and stem in kimchi cabbage provided good ESR signal responses upon irradiation. The signal noise was reduced in case of ALD and WAD pretreatments, particularly due to Mn 2+ signals. The ALD treatment was found most feasible to detect the improved ESR spectra in the irradiated samples. (author)

  16. Conduction electron spin resonance in the α-Yb1−xFexAlB4 (0 ⩽ x ⩽ 0.50) and α-LuAlB4 compounds

    International Nuclear Information System (INIS)

    Holanda, L M; Lesseux, G G; Urbano, R R; Rettori, C; Pagliuso, P G; Magnavita, E T; Ribeiro, R A; Nakatsuji, S; Kuga, K; Fisk, Z; Oseroff, S B

    2015-01-01

    β-YbAlB 4 has become one of the most studied heavy fermion systems since its discovery due to its remarkable physical properties. This system is the first reported Yb-based heavy-fermion superconductor (HFS) for which the low-T superconducting state emerges from a non-fermi-liquid (NFL) normal state associated with quantum criticality Nakatsuji et al 2008 Nature 4 603. Additionally, it presents a striking and unprecedented electron spin resonance (ESR) signal which behaves as a conduction electron spin resonance (CESR) at high temperatures and acquires features of the Yb 3+ local moment ESR at low temperatures. The latter, also named Kondo quasiparticles spin resonance (KQSR), has been defined as a 4f-ce strongly coupled ESR mode that behaves as a local probe of the Kondo quasiparticles in a quantum critical regime, Holanda et al 2011 Phys. Rev. Lett. 107 026402. Interestingly, β-YbAlB 4 possesses a previously known structural variant, namely the α-YbAlB 4 , phase which is a paramagnetic Fermi liquid (FL) at low temperatures Macaluso et al 2007 Chem. Mater. 19 1918. However, it has been recently suggested that the α-YbAlB 4 phase may be tuned to NFL behavior and/or magnetic ordering as the compound is doped with Fe. Here we report ESR studies on the α-Yb 1−x Fe x AlB 4 (0 ⩽ x ⩽ 0.50) series as well as on the reference compound α-LuAlB 4 . For all measured samples, the observed ESR signal behaves as a CESR in the entire temperature range (10 K ≲ T ≲ 300 K) in clear contrast with what has been observed for β-YbAlB 4 . This striking result indicates that the proximity to a quantum critical point is crucial to the occurrence of a KQSR signal. (paper)

  17. Electron spin resonance of Gd3+ in the intermetallic Gd1-xYxNi3Ga9 (0 ≤ x ≤ 0.90) compounds

    Science.gov (United States)

    Mendonça, E. C.; Silva, L. S.; Mercena, S. G.; Meneses, C. T.; Jesus, C. B. R.; Duque, J. G. S.; Souza, J. C.; Pagliuso, P. G.; Lora-Serrano, R.; Teixeira-Neto, A. A.

    2017-10-01

    In this work, experiments of X-ray diffraction, magnetic susceptibility, heat capacitance, and Electron Spin Resonance (ESR) carried out in the Gd1-xYxNi3Ga9 (0 ≤ x ≤ 0.90) compounds grown through a Ga self flux method are reported. The X-ray diffraction data indicate that these compounds crystallize in a trigonal crystal structure with a space group R32. This crystal structure is unaffected by Y-substitution, which produces a monotonic decrease of the lattice parameters. For the x = 0 compound, an antiferromagnetic phase transition is observed at TN = 19.2 K, which is continuously suppressed as a function of the Y-doping and extrapolates to zero at x ≈ 0.85. The ESR data, taken in the temperature range 15 ≤ T ≤ 300 K, show a single Dysonian Gd3+ line with nearly temperature independent g-values. The linewidth follows a Korringa-like behavior as a function of temperature for all samples. The Korringa rates (b = ΔH /ΔT ) are Y-concentration-dependent indicating a "bottleneck" regime. For the most diluted sample (x = 0.90), when it is believed that the "bottleneck" effect is minimized, we have calculated the q-dependent effective exchange interactions between Gd3+ local moments and the c-e of 〈Jf-ce 2(q ) 〉 1 /2 = 18(2) meV and Jf -c e(q =0 ) = 90(10) meV.

  18. Electron spin resonance in Yb-based Kondo-lattice systems; Elektronenspinresonanz in Yb-basierten Kondogitter-Systemen

    Energy Technology Data Exchange (ETDEWEB)

    Wykhoff, Jan

    2010-07-07

    The systems Yb{sub 1-w}A{sub 1-w}(Rh{sub 1-x}Co{sub x})(Si{sub 1-y}Ge{sub y}){sub 2} with A=La respectively Lu, as well as YbIr{sub 2}Si{sub 2} are studied. The measurements are presented sortedly for systems, dopings, and external parameters. Beside these external parameters furthermore the orientation of the sample related to the quasistatic magnetic field and the microwave magnetic field was varied.

  19. The spin relaxation of nitrogen donors in 6H SiC crystals as studied by the electron spin echo method

    Czech Academy of Sciences Publication Activity Database

    Savchenko, Dariia; Shanina, B.; Kalabukhova, E.; Pöppl, A.; Lančok, Ján; Mokhov, E.

    2016-01-01

    Roč. 119, č. 13 (2016), 1-7, č. článku 135706. ISSN 0021-8979 R&D Projects: GA ČR GP13-06697P; GA MŠk LO1409; GA MŠk LM2015088 Grant - others:SAFMAT(XE) CZ.2.16/3.1.00/22132 Institutional support: RVO:68378271 Keywords : electron spin resonance * SiC * nitrogen donors * relaxation times Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.068, year: 2016

  20. Nickel complexes of o-amidochalcogenophenolate(2-)/o-iminochalcogenobenzosemiquinonate(1-) pi-radical: synthesis, structures, electron spin resonance, and x-ray absorption spectroscopic evidence.

    Science.gov (United States)

    Hsieh, Chung-Hung; Hsu, I-Jui; Lee, Chien-Ming; Ke, Shyue-Chu; Wang, Tze-Yuan; Lee, Gene-Hsiang; Wang, Yu; Chen, Jin-Ming; Lee, Jyh-Fu; Liaw, Wen-Feng

    2003-06-16

    The preparation of complexes trans-[Ni(-SeC(6)H(4)-o-NH-)(2)](-) (1), cis-[Ni(-TeC(6)H(4)-o-NH-)(2)](-) (2), trans-[Ni(-SC(6)H(4)-o-NH-)(2)](-) (3), and [Ni(-SC(6)H(4)-o-S-)(2)](-) (4) by oxidative addition of 2-aminophenyl dichalcogenides to anionic [Ni(CO)(SePh)(3)](-) proves to be a successful approach in this direction. The cis arrangement of the two tellurium atoms in complex 2 is attributed to the intramolecular Te.Te contact interaction (Te.Te contact distance of 3.455 A). The UV-vis electronic spectra of complexes 1 and 2 exhibit an intense absorption at 936 and 942 nm, respectively, with extinction coefficient epsilon > 10000 L mol(-)(1) cm(-)(1). The observed small g anisotropy, the principal g values at g(1) = 2.036, g(2) = 2.062, and g(3) = 2.120 for 1 and g(1) = 2.021, g(2) = 2.119, and g(3) = 2.250 for 2, respectively, indicates the ligand radical character accompanied by the contribution of the singly occupied d orbital of Ni(III). The X-ray absorption spectra of all four complexes show L(III) peaks at approximately 854.5 and approximately 853.5 eV. This may indicate a variation of contribution of the Ni(II)-Ni(III) valence state. According to the DFT calculation, the unpaired electron of complex 1 and 2 is mainly distributed on the 3d(xz)() orbital of the nickel ion and on the 4p(z)() orbital of selenium (tellurium, 5p(z)()) as well as the 2p(z)() orbital of nitrogen of the ligand. On the basis of X-ray structural data, UV-vis absorption, electron spin resonance, magnetic properties, DFT computation, and X-ray absorption (K- and L-edge) spectroscopy, the monoanionic trans-[Ni(-SeC(6)H(4)-o-NH-)(2)](-) and cis-[Ni(-TeC(6)H(4)-o-NH-)(2)](-) complexes are appositely described as a resonance hybrid form of Ni(III)-bis(o-amidochalcogenophenolato(2-)) and Ni(II)-(o-amidochalcogenophenolato(2-))-(o-iminochalcogenobenzosemiquinonato(1-) pi-radical; i.e., complexes 1 and 2 contain delocalized oxidation levels of the nickel ion and ligands.

  1. A multiple dating approach (luminescence and electron spin resonance) to assess rates of crustal deformation using Quaternary fluvial terraces of the lower Moulouya River (NE Morocco)

    Science.gov (United States)

    Bartz, Melanie; Rixhon, Gilles; Duval, Mathieu; King, Georgina; Brückner, Helmut

    2017-04-01

    The Moulouya River, the largest catchment in Morocco, drains an area characterized by active crustal deformation during the Late Cenozoic due to the convergence between the African and Eurasian plates. Our study focuses on the lowermost reach of the river in NE Morocco, where a thrust zone associated with N-S compressive shortening in this region was identified (Barcos et al., 2014; Rixhon et al., 2017). New geomorphological results demonstrate contrasting fluvial environments on each side of the thrust: long-lasting fluvial aggradation, materialized by >37 m-thick stacked fill terraces, and the development of a well-preserved terrace staircase, with three Pleistocene terrace levels, occurred in the footwall and the hanging wall, respectively (Rixhon et al., 2017). Here, we present a preliminary geochronological background for these contrasting terrace systems based on a multiple dating approach. Samples for (i) luminescence (pIRIR225 and pIRIR290 dating of coarse-grained K-feldspars) and (ii) electron spin resonance (ESR dating of coarse-grained quartz) from four different profiles were collected. (i) Due to the application of the athermal detrapping model by Huntley (2006) (modified after Kars et al., 2008), it appears that the feldspar signals are in sample specific field saturation. Our results yielded minimum ages of 0.9 Ma and 0.7 Ma for the footwall and hanging wall, respectively. (ii) Using the multiple centre approach with ESR dating (Duval et al., 2015), we measured both the aluminium (Al) and the titanium (Ti) centres in order to evaluate whether they would provide consistent results. Results indicate that De values of the Al centre are either slightly higher compared to those of the Ti centre or they agree within a 1σ-error range, which may simply be due to the slower bleaching kinetics of the Al centre. Thus, the ESR ages were inferred from the Ti centre. Ages between 1.35±0.10 and 1.17±0.10 Ma in the footwall show sediment aggradation between MIS

  2. Massively parallel implementations of coupled-cluster methods for electron spin resonance spectra. I. Isotropic hyperfine coupling tensors in large radicals

    Energy Technology Data Exchange (ETDEWEB)

    Verma, Prakash; Morales, Jorge A., E-mail: jorge.morales@ttu.edu [Department of Chemistry and Biochemistry, Texas Tech University, P.O. Box 41061, Lubbock, Texas 79409-1061 (United States); Perera, Ajith [Department of Chemistry and Biochemistry, Texas Tech University, P.O. Box 41061, Lubbock, Texas 79409-1061 (United States); Department of Chemistry, Quantum Theory Project, University of Florida, Gainesville, Florida 32611 (United States)

    2013-11-07

    Coupled cluster (CC) methods provide highly accurate predictions of molecular properties, but their high computational cost has precluded their routine application to large systems. Fortunately, recent computational developments in the ACES III program by the Bartlett group [the OED/ERD atomic integral package, the super instruction processor, and the super instruction architecture language] permit overcoming that limitation by providing a framework for massively parallel CC implementations. In that scheme, we are further extending those parallel CC efforts to systematically predict the three main electron spin resonance (ESR) tensors (A-, g-, and D-tensors) to be reported in a series of papers. In this paper inaugurating that series, we report our new ACES III parallel capabilities that calculate isotropic hyperfine coupling constants in 38 neutral, cationic, and anionic radicals that include the {sup 11}B, {sup 17}O, {sup 9}Be, {sup 19}F, {sup 1}H, {sup 13}C, {sup 35}Cl, {sup 33}S,{sup 14}N, {sup 31}P, and {sup 67}Zn nuclei. Present parallel calculations are conducted at the Hartree-Fock (HF), second-order many-body perturbation theory [MBPT(2)], CC singles and doubles (CCSD), and CCSD with perturbative triples [CCSD(T)] levels using Roos augmented double- and triple-zeta atomic natural orbitals basis sets. HF results consistently overestimate isotropic hyperfine coupling constants. However, inclusion of electron correlation effects in the simplest way via MBPT(2) provides significant improvements in the predictions, but not without occasional failures. In contrast, CCSD results are consistently in very good agreement with experimental results. Inclusion of perturbative triples to CCSD via CCSD(T) leads to small improvements in the predictions, which might not compensate for the extra computational effort at a non-iterative N{sup 7}-scaling in CCSD(T). The importance of these accurate computations of isotropic hyperfine coupling constants to elucidate

  3. Rabi oscillation and electron-spin-echo envelope modulation of the photoexcited triplet spin system in silicon

    Science.gov (United States)

    Akhtar, Waseem; Sekiguchi, Takeharu; Itahashi, Tatsumasa; Filidou, Vasileia; Morton, John J. L.; Vlasenko, Leonid; Itoh, Kohei M.

    2012-09-01

    We report on a pulsed electron paramagnetic resonance (EPR) study of the photoexcited triplet state (S=1) of oxygen-vacancy centers in silicon. Rabi oscillations between the triplet sublevels are observed using coherent manipulation with a resonant microwave pulse. The Hahn echo and stimulated echo decay profiles are superimposed with strong modulations known as electron-spin-echo envelope modulation (ESEEM). The ESEEM spectra reveal a weak but anisotropic hyperfine coupling between the triplet electron spin and a 29Si nuclear spin (I=1/2) residing at a nearby lattice site, that cannot be resolved in conventional field-swept EPR spectra.

  4. Three-electron spin qubits

    Science.gov (United States)

    Russ, Maximilian; Burkard, Guido

    2017-10-01

    The goal of this article is to review the progress of three-electron spin qubits from their inception to the state of the art. We direct the main focus towards the exchange-only qubit (Bacon et al 2000 Phys. Rev. Lett. 85 1758-61, DiVincenzo et al 2000 Nature 408 339) and its derived versions, e.g. the resonant exchange (RX) qubit, but we also discuss other qubit implementations using three electron spins. For each three-spin qubit we describe the qubit model, the envisioned physical realization, the implementations of single-qubit operations, as well as the read-out and initialization schemes. Two-qubit gates and decoherence properties are discussed for the RX qubit and the exchange-only qubit, thereby completing the list of requirements for quantum computation for a viable candidate qubit implementation. We start by describing the full system of three electrons in a triple quantum dot, then discuss the charge-stability diagram, restricting ourselves to the relevant subsystem, introduce the qubit states, and discuss important transitions to other charge states (Russ et al 2016 Phys. Rev. B 94 165411). Introducing the various qubit implementations, we begin with the exchange-only qubit (DiVincenzo et al 2000 Nature 408 339, Laird et al 2010 Phys. Rev. B 82 075403), followed by the RX qubit (Medford et al 2013 Phys. Rev. Lett. 111 050501, Taylor et al 2013 Phys. Rev. Lett. 111 050502), the spin-charge qubit (Kyriakidis and Burkard 2007 Phys. Rev. B 75 115324), and the hybrid qubit (Shi et al 2012 Phys. Rev. Lett. 108 140503, Koh et al 2012 Phys. Rev. Lett. 109 250503, Cao et al 2016 Phys. Rev. Lett. 116 086801, Thorgrimsson et al 2016 arXiv:1611.04945). The main focus will be on the exchange-only qubit and its modification, the RX qubit, whose single-qubit operations are realized by driving the qubit at its resonant frequency in the microwave range similar to electron spin resonance. Two different types of two-qubit operations are presented for the exchange

  5. Electron spin resonance in Cu{sub 1−x}Fe{sub x}Cr{sub 2}Se{sub 4} nanoparticles synthesized with the thermal decomposition method

    Energy Technology Data Exchange (ETDEWEB)

    Edelman, I.S., E-mail: ise@iph.krasn.ru [Kirensky Institute of Physics, Federal Research Center KSC, Russian Academy of Sciences, Krasnoyarsk 660036 (Russian Federation); Zharkov, S.M.; Pankrats, A.I. [Kirensky Institute of Physics, Federal Research Center KSC, Russian Academy of Sciences, Krasnoyarsk 660036 (Russian Federation); Siberian Federal University, Krasnoyarsk 660041 (Russian Federation); Vorotynov, A.M.; Tugarinov, V.I.; Ivantsov, R.D.; Petrov, D.A. [Kirensky Institute of Physics, Federal Research Center KSC, Russian Academy of Sciences, Krasnoyarsk 660036 (Russian Federation); Velikanov, D.A. [Kirensky Institute of Physics, Federal Research Center KSC, Russian Academy of Sciences, Krasnoyarsk 660036 (Russian Federation); Siberian Federal University, Krasnoyarsk 660041 (Russian Federation); Lin, Chun-Rong; Chen, Chin-Chang; Tseng, Yaw-Teng; Hsu, Hua-Shu [National Pingtung University, Pingtung City, Pingtung County 90003, Taiwan (China)

    2017-08-15

    Highlights: • Cu{sub 1−x}Fe{sub x}Cr{sub 2}Se{sub 4} nanoparticles were synthesized as (1 1 1) nanocrystalline plates. • Nanoparticles tend to form stacks consisting of plates attached “face to face”. • ESR parameters demonstrate unusual temperature dependences with a kink at 120–130 K. - Abstract: In this paper, we present a study of the electron spin resonance (ESR) of nanoparticles (NPs) of Cu{sub 1−x}Fe{sub x}Cr{sub 2}Se{sub 4} chalcogenides with x = 0, 0.2, and 0.4. NPs were synthesized via the thermal decomposition of metal chloride salts and selenium powder in a high-temperature organic solvent. According to the XRD and HRTEM data, the NPs were single crystalline nearly hexagonal plates with the structure close to CuCr{sub 2}Se{sub 4} (Fd-3m, a = 10.337 Å). For x = 0 and 0.2, the NPs tend to form long stacks consisting of the plates “face to face” attached to each other due to the magnetostatic interparticle interaction. Only separate NPs were observed in the case of x = 0.4. Peculiarities were revealed in the ESR temperature behavior for the NPs with x = 0 and 0.2 consistent with the features in the temperature dependences of the NPs magnetization. The non-monotonous dependence of the resonance field H{sub res} on the temperature with a kink near 130 K and the energy gap in the resonance spectrum depending on the type of nanoparticle compacting are the distinct peculiarities. One of the main factors is discussed in order to explain the peculiarities: the coexistence of two types of anisotropy in the Cu{sub 1−x}Fe{sub x}Cr{sub 2}Se{sub 4} NPs, in-plain shape anisotropy and magnetocrystalline anisotropy with four easy axes, which increases strongly with the temperature decrease.

  6. Relaxation study of a paramagnetic ion by the observation of nuclear resonance signals

    International Nuclear Information System (INIS)

    Landesman, A.

    1960-01-01

    Dynamic polarization of protons in water containing the paramagnetic ion NO(SO 3 ) 2 was studied, both theoretically and experimentally, as a function of magnetic field. The enhancement of the proton polarization depends appreciably on the relaxation process of the electron spin and so enables us to decide which is the real relaxation process. We tried the two following processes: a) The electron spin is coupled with the nitrogen magnetic moment by hyperfine interaction; if this interaction has an anisotropic part, a relaxation process for the electronic spin will result through the Brownian motion of the ion. b) The relaxation of the electron spin takes place through spin-orbit coupling of the electron spin. Experimental results showed that the relaxation took place through the second process with the help of dynamic polarization we were able to study the relaxation of an electron spin in a liquid without using any electron resonance spectrometer, simply by observing the resonance of a nuclear spin coupled with the electron spin. Reprint of a paper published in Le Journal de Physique et le Radium, t. 20, p. 937-948, 1959 [fr

  7. Electron spin and nuclear spin manipulation in semiconductor nanosystems

    International Nuclear Information System (INIS)

    Hirayama, Yoshiro; Yusa, Go; Sasaki, Satoshi

    2006-01-01

    Manipulations of electron spin and nuclear spin have been studied in AlGaAs/GaAs semiconductor nanosystems. Non-local manipulation of electron spins has been realized by using the correlation effect between localized and mobile electron spins in a quantum dot- quantum wire coupled system. Interaction between electron and nuclear spins was exploited to achieve a coherent control of nuclear spins in a semiconductor point contact device. Using this device, we have demonstrated a fully coherent manipulation of any two states among the four spin levels of Ga and As nuclei. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  8. Observing electron spin resonance between 0.1 and 67 GHz at temperatures between 50 mK and 300 K using broadband metallic coplanar waveguides

    International Nuclear Information System (INIS)

    Wiemann, Yvonne; Simmendinger, Julian; Clauss, Conrad; Bogani, Lapo; Dressel, Martin; Scheffler, Marc; Bothner, Daniel; Koelle, Dieter; Kleiner, Reinhold

    2015-01-01

    We describe a fully broadband approach for electron spin resonance (ESR) experiments, where it is possible to tune not only the magnetic field but also the frequency continuously over wide ranges. Here, a metallic coplanar transmission line acts as compact and versatile microwave probe that can easily be implemented in different cryogenic setups. We perform ESR measurements at frequencies between 0.1 and 67 GHz and at temperatures between 50 mK and room temperature. Three different types of samples (Cr 3+ ions in ruby, organic radicals of the nitronyl-nitroxide family, and the doped semiconductor Si:P) represent different possible fields of application for the technique. We demonstrate that an extremely large phase space in temperature, magnetic field, and frequency for ESR measurements, substantially exceeding the range of conventional ESR setups, is accessible with metallic coplanar lines

  9. Observing electron spin resonance between 0.1 and 67 GHz at temperatures between 50 mK and 300 K using broadband metallic coplanar waveguides

    Energy Technology Data Exchange (ETDEWEB)

    Wiemann, Yvonne; Simmendinger, Julian; Clauss, Conrad; Bogani, Lapo; Dressel, Martin; Scheffler, Marc [1. Physikalisches Institut, Universität Stuttgart, Pfaffenwaldring 57, 70569 Stuttgart (Germany); Bothner, Daniel; Koelle, Dieter; Kleiner, Reinhold [Physikalisches Institut and Center for Collective Quantum Phenomena in LISA+, Universität Tübingen, Auf der Morgenstelle 14, 72076 Tübingen (Germany)

    2015-05-11

    We describe a fully broadband approach for electron spin resonance (ESR) experiments, where it is possible to tune not only the magnetic field but also the frequency continuously over wide ranges. Here, a metallic coplanar transmission line acts as compact and versatile microwave probe that can easily be implemented in different cryogenic setups. We perform ESR measurements at frequencies between 0.1 and 67 GHz and at temperatures between 50 mK and room temperature. Three different types of samples (Cr{sup 3+} ions in ruby, organic radicals of the nitronyl-nitroxide family, and the doped semiconductor Si:P) represent different possible fields of application for the technique. We demonstrate that an extremely large phase space in temperature, magnetic field, and frequency for ESR measurements, substantially exceeding the range of conventional ESR setups, is accessible with metallic coplanar lines.

  10. A comparative thermoluminescence and electron spin resonance study of synthetic carbonated A-type hydroxyapatite

    International Nuclear Information System (INIS)

    Oliveira, L.C.; Rossi, A.M.; Baffa, O.

    2012-01-01

    Intensity of the 150 °C thermoluminescence peak of beta-irradiated carbonated synthetic A-type hydroxyapatite is approximately 12 times higher than that of the noncarbonated material. Deconvolution of the glow curve showed that this peak is a result of a trap distribution. An attempt was made to relate this thermoluminescence peak enhanced by carbonation with the ESR signal of the CO 2 − radical in natural or synthetic hydroxyapatite. - Highlights: ► Synthetic hydroxyapatite was carbonated with CO 2 . ► TL enhanced by 12 times in carbonated synthetic A-type hydroxyapatite. ► EPR and TL were performed to find out a relation between CO 2 − center and the TL. ► No direct relation was found between the CO 2 − center and TL enhancement.

  11. Application of ENDOR-induced electron spin resonance to the study of point defects in solids

    International Nuclear Information System (INIS)

    Niklas, J.R.; Spaeth, J.M.

    1980-01-01

    The technique of ENDOR-induced ESR (EI-ESR) is applied to the investigation of several point defects in insulating crystals. It is shown that the lineshape of the EI-ESR spectrum depends on the ENDOR line used for the experiment. The EI-ESR technique allows the separation of overlapping ESR spectra in the presence of several defects. New applications are the selection of spin states and the determination of relative signs of spin-Hamiltonian parameters, the selection of centre orientations and the assignment of nuclei in complex ENDOR spectra, and the determination of quadrupole interactions which are not resolved in the ENDOR spectrum. (author)

  12. An electron spin resonance study of some gamma-irradiated fruits

    International Nuclear Information System (INIS)

    Maloney, D.R.; Tabner, B.J.; Tabner, V.A.

    1992-01-01

    The ESR spectra of the seeds, skins and stalks of unirradiated and γ-irradiated Chilean white grapes have been obtained and the results compared to those previously reported for Cape black grapes. The high degree of reproducibility of the spectra obtained from the stalks of different varieties of grapes suggest that ESR spectroscopy could form the basis of a viable test to determine their irradiation history. The condition of the stalk prior to irradiation has been found to have little effect on the resulting spectra. The spectra from the stalks, skins and seeds of unirradiated and γ-irradiated apples, pears and cherries have also been examined. Although most of the spectra from irradiated components exhibit extra features, they are sometimes short-lived and restrict the development of ESR as a viable test. (author)

  13. Optical absorption and electron spin resonance studies of Cu 2 in ...

    Indian Academy of Sciences (India)

    B2O3–As2O3 glasses. N Srinivasa Rao Shashidhar ... K Siva Kumar Syed Rahman. Ceramics and Glasses Volume 28 Issue 6 October 2005 pp 589-592 ... Keywords. Glass transition temperature; ESR; optical absorption; bonding parameters.

  14. Electron spin resonance study of x-irradiated single crystals of ammonium chloroacetate

    International Nuclear Information System (INIS)

    Yoshihara, M.

    1978-01-01

    The quadrupole interaction was considered to be a second order perturbation. Using perturbation theory, formulas were derived for the positions and relative intensities of both allowed (Δm = 0) and forbidden (Δm = +- 1, +- 2) transitions. Using this information, expected spectral patterns were constructed for comparison with observed spectra. It has also been possible to determine the signs of chlorine hyperfine coupling parameters. In this way the complete chlorine coupling tensors were obtained for both the magnetic and quadrupole interactions in the CClHCOONH 4 radical. The chlorine magnetic hyperfine couplings are A/sub x/ = 20.5 G perpendicular to the radical plane, A/sub y/ = -5.2 G perpendicular to the C-Cl bond (in the radical plane) and A/sub z/ = -6.3 G in the direction of the C-Cl bond. The quadrupole couplings are P/sub x/ = 2.3 G perpendicular to the radical plane, P/sub y/ = 2.1 G perpendicular to the C-Cl bond (in the plane) and P/sub z/ = -4.4 G in the direction of the C-Cl bond. The hydrogen hyperfine tensor components are A/sub x//sup H/ = -21.8 G perpendicular to the radical plane, A/sub y//sup H/ = -9.3 G in the direction of the C-H bond and A/sub z//sup H/ = -32.5 G perpendicular to the C-H bond (in the radical plane). The g-factor has the values g/sub x/ = 2.0021 perpendicular to the radical plane, g/sub y/ = 2.0080 perpendicular to the C-Cl bond (in the radical plane) and g/sub z/ = 2.0081 in the C-Cl bond. The direction of the C-Cl bond of the radical was inferred. Evaluation of the hydrogen hyperfine couplings has led to the determination of the direction of the C-H bond. From this information the radical was determined to be a planar π-radical. A determination was made of the spin densities of the unpaired electron in the various orbitals: C 2 p/sub x/ = +0.76, Cl 3s = +0.0017, Cl 3p/sub x/ = +0.175, and Cl 3p/sub z/ = -0.012

  15. Electron-spin polarization of photoions produced through photoionization from the laser-excited triplet state of Sr

    International Nuclear Information System (INIS)

    Yonekura, Nobuaki; Nakajima, Takashi; Matsuo, Yukari; Kobayashi, Tohru; Fukuyama, Yoshimitsu

    2004-01-01

    We report the detailed experimental study on the production of electron-spin-polarized Sr + ions through one-photon resonant two-photon ionization via laser-excited 5s5p 3 P 1 (M J =+1) of Sr atoms produced by laser-ablation. We have experimentally confirmed that the use of laser-ablation for the production of Sr atoms prior to photoionization does not affect the electron-spin polarization. We have found that the degree of electron-spin polarization is 64±9%, which is in good agreement with our recent theoretical prediction. As we discuss in detail, we infer, from a simple analysis, that photoelectrons, being the counterpart of electron-spin-polarized Sr + ions, have approximately the same degree of electron-spin polarization. Our experimental results demonstrate that the combined use of laser-ablation technique and pulsed lasers for photoionization would be a compact and effective way to realize a pulsed source for spin-polarized ions and electrons for the studies of various spin-dependent dynamics in chemical physics

  16. Electron Spin Resonance Shift and Linewidth Broadening of Nitrogen-Vacancy Centers in Diamond as a Function of Electron Irradiation Dose

    OpenAIRE

    Kim, Edwin; Acosta, Victor M.; Bauch, Erik; Budker, Dmitry; Hemmer, Philip R.

    2009-01-01

    A high-nitrogen-concentration diamond sample was subject to 200-keV electron irradiation using a transmission electron microscope. The optical and spin-resonance properties of the nitrogen-vacancy (NV) color centers were investigated as a function of the irradiation dose up to 6.4\\times1021 e-/cm2. The microwave transition frequency of the NV- center was found to shift by up to 0.6% (17.1 MHz) and the linewidth broadened with increasing electron-irradiation dose. Unexpectedly, the measured ma...

  17. Field dependence of the electron spin relaxation in quantum dots.

    Science.gov (United States)

    Calero, Carlos; Chudnovsky, E M; Garanin, D A

    2005-10-14

    The interaction of the electron spin with local elastic twists due to transverse phonons is studied. The universal dependence of the spin-relaxation rate on the strength and direction of the magnetic field is obtained in terms of the electron gyromagnetic tensor and macroscopic elastic constants of the solid. The theory contains no unknown parameters and it can be easily tested in experiment. At high magnetic field it provides a parameter-free lower bound on the electron spin relaxation in quantum dots.

  18. Off-centre dynamic Jahn-Teller effect studied by electron spin relaxation of Cu2+ ions in SrF2 crystal

    International Nuclear Information System (INIS)

    Hoffmann, S.K.

    2000-01-01

    Temperature cw-EPR and pulsed EPR electron spin echo experiments were performed for a low concentration of Cu 2+ ions in cubic SrF 2 crystals. The well resolved EPR spectrum at low temperatures (below 30 K) with parameters g parallel = 2.493, g perpendicular = 2.083, A parallel = 121, A perpendicular = 8.7, A parallel ( 19 F) = 135, A parallel ( 19 F) = 33.0 (A-values in 10 -4 cm -1 ) is transformed continuously into a single broad line above 225 K on heating, due to the g-factor shift and EPR line broadening. These data along with the angular variation EPR data are described in terms of a pseudo-Jahn-Teller effect of (T 2g +A 2u )x(a 1g +e g +t 1u ) type producing six off-centre positions of the Cu 2+ ion in the fluorine cube. Above 30 K a two-step averaging g -factor process occurs and is governed by vibronic dynamics between potential wells of the off-centre positions. This dynamics governs the electron spin relaxation in the whole temperature range. The electron spin-lattice relaxation rate 1/T 1 grows rapidly by six orders of magnitude in the temperature range 30-100 K and is determined by the Orbach-type process with excitations to two excited vibronic levels of energy 83 and 174 cm -1 . For higher temperatures the relaxation is dominated by overbarrier jumps leading to the isotropic EPR spectrum above 225 K. The phase memory time T M has the rigid lattice value 3.5 μs determined by nuclear spectral diffusion and its temperature variation is governed by the vibronic dynamics indicating that the excitations between vibronic levels produce a dephasing of the electron spin precessional motion. (author)

  19. Results of electron spin resonance measurement of cow teeth from a village around the Indian Nuclear Test Site and assessment of the human exposure to radiation

    International Nuclear Information System (INIS)

    Bhattacharjee, Deborshi; Hoshi, Masaharu; Ivannikov, Alexander; Ohtaki, Megu; Sarma, Haladhar D.

    2010-01-01

    A number of cow tooth samples are collected from the adjacent village of Khetolai, located 5 km from the actual Indian Nuclear Test Site in Rajasthan. The samples were processed and utilized for ESR measurements in this study by an X-band spectrometer from JEOL, Japan. The excess dose, determined by subtraction of the natural background dose from the dose absorbed by the enamel was found to the extent of 142 mGy. The intensity of ESR measurement of cow teeth, however, is lower than the human teeth in general. The detailed results obtained on dose estimation in the present study and its correlation with dose exposure for human beings as a result of nuclear test will be presented. The results of this study amply suggest that there is no direct evidence attributing to the development tumors in the cattle population of the locality. There are definitely other factors which were responsible for occurrence of such tumors and other congenital defects in the animal population in the area

  20. Development of methods for determining organic free radical structures by electron spin resonance and application to the radiation chemistry of nucleic acid model compounds

    International Nuclear Information System (INIS)

    Fouse, G.W. Jr.

    1977-01-01

    This project was undertaken with the objective of developing more efficient and reliable methods for the analysis of free radicals in organic single crystals. A technique was developed for the rapid calculation of single crystal ESR line positions and intensities. This method, which avoids the time-consuming matrix operations required by conventional methods, has been incorporated into a computer program for determining ESR parameters by the least-squares fitting of digitized ESR spectra. This program has been used to analyze complex spectra arising from a . CH 2 -CH 2 -O-PO 3 H - radical trapped in O-phosphorylethanolamine. A method was developed for the estimation of variance and covariance of eigenvectors and eigenvalues of experimentally-determined tensors. This error analysis is quite general, and may be applied to any tensors which can be determined by the non-linear least-squares fitting of ESR data. Monte-Carlo simulations have been employed to estimate the limitations of the approximation method. This error analysis has been included in the analysis of two phosphite radicals, - O 2 -P-OX, found in single crystals of O-phosphorylethanolamine. To aid in the formulation and evaluation of free radical models, a generalized method for the calculation of theoretically-expected hyperfine coupling tensors for arbitrary radical models was developed. Tensors are calculated for a furan-type radical which may be found in 5' dCMP. These calculated tensors are compared with tensors determined by an ENDOR experiment. Two ENDOR studies were done, one in 5' dCMP, the other in L-asparagine. The observed radical in 5' dCMP is allylic, characterized by coupling to three α-hydrogens. In L-asparagine, the dominant room-temperature radical has the form CO(NH 2 )CHCH(N + H 3 )CO 2 - . In both these studies, a series of molecular orbital calculations were performed as a means of substantiating the postulated radical structures

  1. Electron spin dynamics of Ce.sup.3+./sup. ions in YAG crystals studied by pulse-EPR and pump-probe Faraday rotation

    Czech Academy of Sciences Publication Activity Database

    Azamat, Dmitry; Belykh, V.V.; Yakovlev, D.R.; Fobbe, F.; Feng, D.H.; Evers, E.; Jastrabík, Lubomír; Dejneka, Alexandr; Bayer, M.

    2017-01-01

    Roč. 96, č. 7 (2017), s. 1-10, č. článku 075160. ISSN 2469-9950 R&D Projects: GA MŠk LO1409; GA ČR GA16-22092S Institutional support: RVO:68378271 Keywords : electron spin dynamics * Ce 3+ ions * YAG crystals * pulse-EPR * Faraday rotation Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 3.836, year: 2016

  2. Numerical dating of a Late Quaternary spit-shoreline complex at the northern end of Silver Lake playa, Mojave Desert, California: A comparison of the applicability of radiocarbon, luminescence, terrestrial cosmogenic nuclide, electron spin resonance, U-series and amino acid racemization methods

    Science.gov (United States)

    Owen, L.A.; Bright, Jordon; Finkel, R.C.; Jaiswal, M.K.; Kaufman, D.S.; Mahan, S.; Radtke, U.; Schneider, J.S.; Sharp, W.; Singhvi, A.K.; Warren, C.N.

    2007-01-01

    A Late Quaternary spit-shoreline complex on the northern shore of Pleistocene Lake Mojave of southeastern California, USA was studied with the goal of comparing accelerator mass spectrometry (AMS) radiocarbon, luminescence, electron spin resonance (ESR), terrestrial cosmogenic radionuclide (TCN) surface exposure, amino acid racemization (AAR) and U-series dating methods. The pattern of ages obtained by the different methods illustrates the complexity of processes acting in the lakeshore environment and highlights the utility of a multi-method approach. TCN surface exposure ages (mostly ???20-30 ka) record the initial erosion of shoreline benches, whereas radiocarbon ages on shells (determined in this and previous studies) within the spit, supported by AAR data, record its construction at fluctuating lake levels from ???16 to 10 ka. Luminescence ages on spit sediment (???6-7 ka) and ESR ages on spit shells (???4 ka) are anomalously young relative to radiocarbon ages of shells within the same deposits. The significance of the surprisingly young luminescence ages is not clear. The younger ESR ages could be a consequence of post-mortem enrichment of U in the shells. High concentrations of detrital thorium in tufa coating spit gravels inhibited the use of single-sample U-series dating. Detailed comparisons such as this provide one of the few means of assessing the accuracy of Quaternary dating techniques. More such comparisons are needed. ?? 2007 Elsevier Ltd and INQUA.

  3. Few electron quantum dot coupling to donor implanted electron spins

    Science.gov (United States)

    Rudolph, Martin; Harvey-Collard, Patrick; Neilson, Erik; Gamble, John; Muller, Richard; Jacobson, Toby; Ten-Eyck, Greg; Wendt, Joel; Pluym, Tammy; Lilly, Michael; Carroll, Malcolm

    2015-03-01

    Donor-based Si qubits are receiving increased interest because of recent demonstrations of high fidelity electron or nuclear spin qubits and their coupling. Quantum dot (QD) mediated interactions between donors are of interest for future coupling of two donors. We present experiment and modeling of a polysilicon/Si MOS QD, charge-sensed by a neighboring many electron QD, capable of coupling to one or two donor implanted electron spins (D) while tuned to the few electron regime. The unique design employs two neighboring gated wire FETs and self-aligned implants, which supports many configurations of implanted donors. We can access the (0,1) ⇔(1,0) transition between the D and QD, as well as the resonance condition between the few electron QD and two donors ((0,N,1) ⇔(0,N +1,0) ⇔(1,N,0)). We characterize capacitances and tunnel rate behavior combined with semi-classical and full configuration interaction simulations to study the energy landscape and kinetics of D-QD transitions. This work was performed, in part, at the Center for Integrated Nanotechnologies, a U.S. DOE, Office of Basic Energy Sciences user facility. The work was supported by the Sandia National Laboratories Directed Research and Development Program. Sandia National Laboratories is a multi-program laboratory operated by Sandia Corporation, a Lockheed-Martin Company, for the U. S. Department of Energy under Contract No. DE-AC04-94AL85000.

  4. Electron Spins in Semiconductor Quantum Dots

    NARCIS (Netherlands)

    Hanson, R.

    2005-01-01

    This thesis describes a series of experiments aimed at understanding and controlling the behavior of the spin degree of freedom of single electrons, confined in semiconductor quantum dots. This research work is motivated by the prospects of using the electron spin as a quantum bit (qubit), the basic

  5. Quantum Computing with an Electron Spin Ensemble

    DEFF Research Database (Denmark)

    Wesenberg, Janus; Ardavan, A.; Briggs, G.A.D.

    2009-01-01

    We propose to encode a register of quantum bits in different collective electron spin wave excitations in a solid medium. Coupling to spins is enabled by locating them in the vicinity of a superconducting transmission line cavity, and making use of their strong collective coupling to the quantized...

  6. Dephasing of optically generated electron spins in semiconductors

    International Nuclear Information System (INIS)

    Idrish Miah, M.

    2010-01-01

    Dephasing of optically generated electron spins in the presence of the external magnetic field and electric bias in semiconductor nano-structures has been studied by time- and polarization-resolved spectrometry. The obtained experimental data are presented in dependence of the strength of the magnetic field. The optically generated electron-spin precession frequency and dephasing time and rate are estimated. It is found that both the spin precession frequency and dephasing rate increase linearly with the external magnetic field up to about 9 T. However, the spin dephasing time is within sub-μs and is found to decrease exponentially with the strength of the external magnetic field. The results are discussed by exploring possible mechanisms of spin dephasing in low-dimensional semiconductor structures, where the quantum-confinement persists within the nano-range.

  7. Dephasing of optically generated electron spins in semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Idrish Miah, M., E-mail: m.miah@griffith.edu.a [Department of Physics, University of Chittagong, Chittagong, Chittagong - 4331 (Bangladesh)

    2010-09-13

    Dephasing of optically generated electron spins in the presence of the external magnetic field and electric bias in semiconductor nano-structures has been studied by time- and polarization-resolved spectrometry. The obtained experimental data are presented in dependence of the strength of the magnetic field. The optically generated electron-spin precession frequency and dephasing time and rate are estimated. It is found that both the spin precession frequency and dephasing rate increase linearly with the external magnetic field up to about 9 T. However, the spin dephasing time is within sub-{mu}s and is found to decrease exponentially with the strength of the external magnetic field. The results are discussed by exploring possible mechanisms of spin dephasing in low-dimensional semiconductor structures, where the quantum-confinement persists within the nano-range.

  8. Study on Mo(V) species, location and adsorbates interactions in MoH-SAPO-34 by employing ESR and electron spin-echo modulation spectroscopies

    International Nuclear Information System (INIS)

    Back, Gern Ho; Jang, Chang Ki; Ru, Chang Kuk; Cho, Young Hwan; So, Hyun Soo; Larry, Keven

    2002-01-01

    A solid-state reaction of MoO 3 with as-synthesized H-SAPO-34 generated paramagnetic Mo(V) species. The dehydration resulted in weak Mo(V) species, and subsequent activation resulted in the formation of Mo(V) species such as Mo(V) 5c and Mo(V) 6c that are characterized by ESR. The data of ESR and ESEM show the oxomolybdenum species, to be (MoO 2 ) + or (MoO) 3+ . The (MoO 2 ) + species seems to be more probable. Since H-SAPO-34 has a low framework negative charge, (MoO) 3+ with a high positive charge can not be easily stabilized. A solution reaction between the solution of silico-molybdic acid and calcined H-SAPO-34 resulted in only MoO + 2 species. A rhombic ESR signal is observed on adsorption of D 2 O, CD 3 OH, CH 3 CH 2 OD and ND 3 . The Location and coordination structure of Mo(V) species has been determined by three-pulse electron spin-echo modulation data and their simulations. After the adsorption of methanol, ethylene, ammonia, and water for MoH-SAPO-34, three molecules, one and one molecule, respectively, are directly coordinated to (MoO 2 ) +

  9. Electron spin control and torsional optomechanics of an optically levitated nanodiamond in vacuum

    Science.gov (United States)

    Li, Tongcang; Hoang, Thai; Ahn, Jonghoon; Bang, Jaehoon

    Electron spins of diamond nitrogen-vacancy (NV) centers are important quantum resources for nanoscale sensing and quantum information. Combining such NV spin systems with levitated optomechanical resonators will provide a hybrid quantum system for many novel applications. Here we optically levitate a nanodiamond and demonstrate electron spin control of its built-in NV centers in vacuum. We observe that the strength of electron spin resonance (ESR) is enhanced when the air pressure is reduced. We also observe that oxygen and helium gases have different effects on both the photoluminescence and the ESR contrast of nanodiamond NV centers, indicating potential applications of NV centers in oxygen gas sensing. For spin-optomechanics, it is important to control the orientation of the nanodiamond and NV centers in a magnetic field. Recently, we have observed the angular trapping and torsional vibration of a levitated nanodiamond, which paves the way towards levitated torsional optomechanics in the quantum regime. NSF 1555035-PHY.

  10. Low-control and robust quantum refrigerator and applications with electronic spins in diamond

    Science.gov (United States)

    Mohammady, M. Hamed; Choi, Hyeongrak; Trusheim, Matthew E.; Bayat, Abolfazl; Englund, Dirk; Omar, Yasser

    2018-04-01

    We propose a general protocol for low-control refrigeration and thermometry of thermal qubits, which can be implemented using electronic spins in diamond. The refrigeration is implemented by a probe, consisting of a network of interacting spins. The protocol involves two operations: (i) free evolution of the probe; and (ii) a swap gate between one spin in the probe and the thermal qubit we wish to cool. We show that if the initial state of the probe falls within a suitable range, and the free evolution of the probe is both unital and conserves the excitation in the z direction, then the cooling protocol will always succeed, with an efficiency that depends on the rate of spin dephasing and the swap-gate fidelity. Furthermore, measuring the probe after it has cooled many qubits provides an estimate of their temperature. We provide a specific example where the probe is a Heisenberg spin chain, and suggest a physical implementation using electronic spins in diamond. Here, the probe is constituted of nitrogen vacancy (NV) centers, while the thermal qubits are dark spins. By using a novel pulse sequence, a chain of NV centers can be made to evolve according to a Heisenberg Hamiltonian. This proposal allows for a range of applications, such as NV-based nuclear magnetic resonance of photosensitive molecules kept in a dark spot on a sample, and it opens up possibilities for the study of quantum thermodynamics, environment-assisted sensing, and many-body physics.

  11. Reduction of antitumour mitosenes in non-aqueous and aqueous environment. An electron spin resonance and cyclic voltammetry study

    NARCIS (Netherlands)

    Maliepaard, M.; de Mol, N.J.; Janssen, H.L.; Goeptar, A R; te Koppele, J.M.; Vermeulen, N P; Verboom, W.; Reinhoudt, David N

    Chemical reduction of mitosenes under aerobic conditions in DMSO showed characteristic ESR signals of the mitosene derived semiquinone free radicals. However, these signals diminished strongly upon addition of water to the reaction mixture, indicating a short lifetime of the mitosene semiquinone

  12. Reduction of antitumour mitosenes in non-aqueous and aqueous environment. An electron spin resonance and cyclic voltammetry study.

    NARCIS (Netherlands)

    Maliepaard, M.; de Mol, N.J.; Janssen, L.H.M.; Goeptar, A.R.; te Koppele, J.M.; Vermeulen, N.P.E.; Verboom, W.; Reinhoudt, D.N.

    1995-01-01

    Chemical reduction of mitosenes under aerobic conditions in DMSO showed characteristic ESR signals of the mitosene derived semiquinone free radicals. However, these signals diminished strongly upon addition of water to the reaction mixture, indicating a short lifetime of the mitosene semiquinone

  13. Electron spin resonance study of self-trapped holes in CdWO.sub.4./sub. scintillator crystals

    Czech Academy of Sciences Publication Activity Database

    Laguta, Valentyn; Nikl, Martin; Rosa, Jan; Grinyov, B.V.; Nagornaya, L.L.; Tupitsina, I.A.

    2008-01-01

    Roč. 104, č. 10 (2008), 103525/1-103525/6 ISSN 0021-8979 R&D Projects: GA AV ČR IAA100100810 Institutional research plan: CEZ:AV0Z10100521 Keywords : scintillator * EPR * point defects Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.201, year: 2008

  14. Mechanism of initiation of oxidation in mayonnaise enriched with fish oil as studied by electron spin resonance spectroscopy

    DEFF Research Database (Denmark)

    Thomsen, M.K.; Jacobsen, Charlotte; Skibsted, L.H.

    2000-01-01

    degreesC as quantified using 12-doxylstearic acid. Sugar, NaCl and potassium sorbate have no effect on radical formation while EDTA (down to 50 mug/g) has an antioxidative effect. Iron bound to phosvitin in egg yolk, inactive at pH similar to6, is considered to be exposed to the solvent (the aqueous phase......) at low pH and capable of initiating peroxide cleavage reactions when not protected by EDTA in a mixed complex...

  15. Pulse Double-Resonance EPR Techniques for the Study of Metallobiomolecules.

    Science.gov (United States)

    Cox, Nicholas; Nalepa, Anna; Pandelia, Maria-Eirini; Lubitz, Wolfgang; Savitsky, Anton

    2015-01-01

    Electron paramagnetic resonance (EPR) spectroscopy exploits an intrinsic property of matter, namely the electron spin and its related magnetic moment. This can be oriented in a magnetic field and thus, in the classical limit, acts like a little bar magnet. Its moment will align either parallel or antiparallel to the field, giving rise to different energies (termed Zeeman splitting). Transitions between these two quantized states can be driven by incident microwave frequency radiation, analogous to NMR experiments, where radiofrequency radiation is used. However, the electron Zeeman interaction alone provides only limited information. Instead, much of the usefulness of EPR is derived from the fact that the electron spin also interacts with its local magnetic environment and thus can be used to probe structure via detection of nearby spins, e.g., NMR-active magnetic nuclei and/or other electron spin(s). The latter is exploited in spin labeling techniques, an exciting new area in the development of noncrystallographic protein structure determination. Although these interactions are often smaller than the linewidth of the EPR experiment, sophisticated pulse EPR methods allow their detection. A number of such techniques are well established today and can be broadly described as double-resonance methods, in which the electron spin is used as a reporter. Below we give a brief description of pulse EPR methods, particularly their implementation at higher magnetic fields, and how to best exploit them for studying metallobiomolecules. © 2015 Elsevier Inc. All rights reserved.

  16. Theory of electron spin echoes in solids

    CERN Document Server

    Asadullina, N Y; Asadullin, Y Y

    2002-01-01

    We propose modified Bloch equations (MBEs) with specific power-dependent relaxation and dispersion parameters characteristic for two-pulse excitation and when the magnetic dipole-dipole interactions in the electron spin system control the dephasing. We discriminate between the 'active' (excited by both pulses) and 'passive' (excited by the second pulse only) spins: it is shown that the 'active' spins participate in a new effect, an active spin frequency modulation effect giving rise to the power-dependent dispersion and multiple electron spin echoes (ESEs); the 'passive' spins contribute to the power-dependent relaxation. The MBEs are solved and a general expression for the two-pulse ESEs is obtained. Detailed numerical analysis of this expression gives results in good quantitative agreement with the recent experiments on the two-pulse ESEs at conventional low applied fields. The developed theory is applied also to high field ESEs, which are promising for future investigations. On the basis of published resul...

  17. Electron spin torque in atoms

    International Nuclear Information System (INIS)

    Hara, Takaaki; Senami, Masato; Tachibana, Akitomo

    2012-01-01

    The spin torque and zeta force, which govern spin dynamics, are studied by using monoatoms in their steady states. We find nonzero local spin torque in transition metal atoms, which is in balance with the counter torque, the zeta force. We show that d-orbital electrons have a crucial effect on these torques. Nonzero local chirality density in transition metal atoms is also found, though the electron mass has the effect to wash out nonzero chirality density. Distribution patterns of the chirality density are the same for Sc–Ni atoms, though the electron density distributions are different. -- Highlights: ► Nonzero local spin torque is found in the steady states of transition metal atoms. ► The spin steady state is realized by the existence of a counter torque, zeta force. ► D-orbital electrons have a crucial effect on the spin torque and zeta force. ► Nonzero local chiral density is found in spite of the washout by the electron mass. ► Chiral density distribution have the same pattern for Sc–Ni atoms.

  18. Multiple stable states of a periodically driven electron spin in a quantum dot using circularly polarized light

    Science.gov (United States)

    Korenev, V. L.

    2011-06-01

    The periodical modulation of circularly polarized light with a frequency close to the electron spin resonance frequency induces a sharp change of the single electron spin orientation. Hyperfine interaction provides a feedback, thus fixing the precession frequency of the electron spin in the external and the Overhauser field near the modulation frequency. The nuclear polarization is bidirectional and the electron-nuclear spin system (ENSS) possesses a few stable states. The same physics underlie the frequency-locking effect for two-color and mode-locked excitations. However, the pulsed excitation with mode-locked laser brings about the multitudes of stable states in ENSS in a quantum dot. The resulting precession frequencies of the electron spin differ in these states by the multiple of the modulation frequency. Under such conditions ENSS represents a digital frequency converter with more than 100 stable channels.

  19. Hybrid quantum circuit with a superconducting qubit coupled to an electron spin ensemble

    Energy Technology Data Exchange (ETDEWEB)

    Kubo, Yuimaru; Grezes, Cecile; Vion, Denis; Esteve, Daniel; Bertet, Patrice [Quantronics Group, SPEC (CNRS URA 2464), CEA-Saclay, 91191 Gif-sur-Yvette (France); Diniz, Igor; Auffeves, Alexia [Institut Neel, CNRS, BP 166, 38042 Grenoble (France); Isoya, Jun-ichi [Research Center for Knowledge Communities, University of Tsukuba, 305-8550 Tsukuba (Japan); Jacques, Vincent; Dreau, Anais; Roch, Jean-Francois [LPQM (CNRS, UMR 8537), Ecole Normale Superieure de Cachan, 94235 Cachan (France)

    2013-07-01

    We report the experimental realization of a hybrid quantum circuit combining a superconducting qubit and an ensemble of electronic spins. The qubit, of the transmon type, is coherently coupled to the spin ensemble consisting of nitrogen-vacancy (NV) centers in a diamond crystal via a frequency-tunable superconducting resonator acting as a quantum bus. Using this circuit, we prepare arbitrary superpositions of the qubit states that we store into collective excitations of the spin ensemble and retrieve back into the qubit. We also report a new method for detecting the magnetic resonance of electronic spins at low temperature with a qubit using the hybrid quantum circuit, as well as our recent progress on spin echo experiments.

  20. Electron-Spin Precession in Dependence of the Orientation of the External Magnetic Field.

    Science.gov (United States)

    Miah, M Idrish

    2009-03-13

    Electron-spin dynamics in semiconductor-based heterostructures has been investigated in oblique magnetic fields. Spins are generated optically by a circularly polarized light, and the dynamics of spins in dependence of the orientation (theta) of the magnetic field are studied. The electron-spin precession frequency, polarization amplitude, and decay rate as a function of theta are obtained and the reasons for their dependences are discussed. From the measured data, the values of the longitudinal and transverse components of the electron g-factor are estimated and are found to be in good agreement with those obtained in earlier investigations. The possible mechanisms responsible for the observed effects are also discussed.

  1. Differential saturation study of radial and angular modulation mechanisms of electron spin--lattice relaxation for trapped hydrogen atoms in sulfuric acid glasses. [X radiation

    Energy Technology Data Exchange (ETDEWEB)

    Plonka, A; Kevan, L

    1976-11-01

    A differential ESR saturation study of allowed transitions and forbidden proton spin-flip satellite transitions for trapped hydrogen atoms in sulfuric acid glasses indicates that angular modulation dominates the spin-lattice relaxation mechanisms and suggests that the modulation arises from motion of the H atom.

  2. Origin of the decoherence of the extended electron spin state in Ti-doped β-Ga2O3.

    Science.gov (United States)

    Mentink-Vigier, F; Binet, L; Gourier, D; Vezin, H

    2013-08-07

    The mechanism of decoherence of the electron spin of Ti(3+) in β-Ga2O3 was investigated by pulsed electron paramagnetic resonance. At 4.2 K, both instantaneous and spectral diffusion contribute to the decoherence. For electron spin concentrations ≈10(25) m(-3) in the studied samples, calculations indicate that electron-electron couplings and electron couplings with (69)Ga and (71)Ga nuclei yield similar contributions to the spectral diffusion, but that electron-nuclei interactions could become the dominant cause of spectral diffusion for only slightly lower spin concentrations. Above 20 K, an additional contribution to the decoherence as well as to the spin-lattice relaxation arises from a two-optical-phonon Raman process, which becomes the leading decoherence mechanism for T > 39 K. Rabi oscillations with a damping time of about 79 ns at 4.2 K could also be observed. The damping of the Rabi oscillations, independent of the oscillation frequency, is suspected to arise from electron-nuclei interactions.

  3. The spin relaxation of nitrogen donors in 6H SiC crystals as studied by the electron spin echo method

    Science.gov (United States)

    Savchenko, D.; Shanina, B.; Kalabukhova, E.; Pöppl, A.; Lančok, J.; Mokhov, E.

    2016-04-01

    We present the detailed study of the spin kinetics of the nitrogen (N) donor electrons in 6H SiC wafers grown by the Lely method and by the sublimation "sandwich method" (SSM) with a donor concentration of about 1017 cm-3 at T = 10-40 K. The donor electrons of the N donors substituting quasi-cubic "k1" and "k2" sites (Nk1,k2) in both types of the samples revealed the similar temperature dependence of the spin-lattice relaxation rate (T1-1), which was described by the direct one-phonon and two-phonon processes induced by the acoustic phonons proportional to T and to T9, respectively. The character of the temperature dependence of the T1-1 for the donor electrons of N substituting hexagonal ("h") site (Nh) in both types of 6H SiC samples indicates that the donor electrons relax through the fast-relaxing centers by means of the cross-relaxation process. The observed enhancement of the phase memory relaxation rate (Tm-1) with the temperature increase for the Nh donors in both types of the samples, as well as for the Nk1,k2 donors in Lely grown 6H SiC, was explained by the growth of the free electron concentration with the temperature increase and their exchange scattering at the N donor centers. The observed significant shortening of the phase memory relaxation time Tm for the Nk1,k2 donors in the SSM grown sample with the temperature lowering is caused by hopping motion of the electrons between the occupied and unoccupied states of the N donors at Nh and Nk1,k2 sites. The impact of the N donor pairs, triads, distant donor pairs formed in n-type 6H SiC wafers on the spin relaxation times was discussed.

  4. The spin relaxation of nitrogen donors in 6H SiC crystals as studied by the electron spin echo method

    Energy Technology Data Exchange (ETDEWEB)

    Savchenko, D., E-mail: dariyasavchenko@gmail.com [Institute of Physics of the Czech Academy of Sciences, Prague 182 21 (Czech Republic); National Technical University of Ukraine “Kyiv Polytechnic Institute,” Kyiv 03056 (Ukraine); Shanina, B.; Kalabukhova, E. [V.E. Lashkaryov Institute of Semiconductor Physics, NASU, Kyiv 03028 (Ukraine); Pöppl, A. [Institute of Experimental Physics II, Leipzig University, Leipzig D-04103 (Germany); Lančok, J. [Institute of Physics of the Czech Academy of Sciences, Prague 182 21 (Czech Republic); Mokhov, E. [A.F. Ioffe Physical Technical Institute, RAS, St. Petersburg 194021 (Russian Federation); Saint-Petersburg National Research University of Information Technologies, Mechanics and Optics, St. Petersburg 19710 (Russian Federation)

    2016-04-07

    We present the detailed study of the spin kinetics of the nitrogen (N) donor electrons in 6H SiC wafers grown by the Lely method and by the sublimation “sandwich method” (SSM) with a donor concentration of about 10{sup 17 }cm{sup −3} at T = 10–40 K. The donor electrons of the N donors substituting quasi-cubic “k1” and “k2” sites (N{sub k1,k2}) in both types of the samples revealed the similar temperature dependence of the spin-lattice relaxation rate (T{sub 1}{sup −1}), which was described by the direct one-phonon and two-phonon processes induced by the acoustic phonons proportional to T and to T{sup 9}, respectively. The character of the temperature dependence of the T{sub 1}{sup −1} for the donor electrons of N substituting hexagonal (“h”) site (N{sub h}) in both types of 6H SiC samples indicates that the donor electrons relax through the fast-relaxing centers by means of the cross-relaxation process. The observed enhancement of the phase memory relaxation rate (T{sub m}{sup −1}) with the temperature increase for the N{sub h} donors in both types of the samples, as well as for the N{sub k1,k2} donors in Lely grown 6H SiC, was explained by the growth of the free electron concentration with the temperature increase and their exchange scattering at the N donor centers. The observed significant shortening of the phase memory relaxation time T{sub m} for the N{sub k1,k2} donors in the SSM grown sample with the temperature lowering is caused by hopping motion of the electrons between the occupied and unoccupied states of the N donors at N{sub h} and N{sub k1,k2} sites. The impact of the N donor pairs, triads, distant donor pairs formed in n-type 6H SiC wafers on the spin relaxation times was discussed.

  5. Electron spin relaxation in cryptochrome-based magnetoreception

    DEFF Research Database (Denmark)

    Kattnig, Daniel R; Solov'yov, Ilia A; Hore, P J

    2016-01-01

    The magnetic compass sense of migratory birds is thought to rely on magnetically sensitive radical pairs formed photochemically in cryptochrome proteins in the retina. An important requirement of this hypothesis is that electron spin relaxation is slow enough for the Earth's magnetic field to have...... this question for a structurally characterized model cryptochrome expected to share many properties with the putative avian receptor protein. To this end we combine all-atom molecular dynamics simulations, Bloch-Redfield relaxation theory and spin dynamics calculations to assess the effects of spin relaxation...... on the performance of the protein as a compass sensor. Both flavin-tryptophan and flavin-Z˙ radical pairs are studied (Z˙ is a radical with no hyperfine interactions). Relaxation is considered to arise from modulation of hyperfine interactions by librational motions of the radicals and fluctuations in certain...

  6. Electron spin polarization in high-energy storage rings

    International Nuclear Information System (INIS)

    Mane, S.R.

    1987-01-01

    In a high energy storage ring, a single photon emission has relatively little effect on the orbital motion, but it can produce a relatively large change in the electron spin state. Hence the unperturbed orbital motion can be satisfactorily described using classical mechanics, but the spin must be treated quantum mechanically. The electron motion is therefore treated semi-classically in this thesis. It is explained how to diagonalize the unperturbed Hamiltonian to the leading order in Planck's constant. The effects of perturbations are then included, and the relevant time-scales and ensemble averages are elucidated. The Derbenev-Kondratenko formula for the equilibrium degree of polarization is rederived. Mathematical details of the rederivation are given. Since the original authors used a different formalism, a proof is offered of the equivalence between their method and the one used in this thesis. An algorithm is also presented to evaluate the equilibrium polarization. It has a number of new features, which enable the polarization to be calculated to a higher degree of approximation than has hitherto been possible. This facilitates the calculation of so-called spin resonances, which are points at which the polarization almost vanishes. A computer program has been written to implement the above algorithm, in the approximation of linear orbital dynamics, and sample results are presented

  7. Relaxation of the electron spin in quantum dots via one- and two-phonon processes

    International Nuclear Information System (INIS)

    Calero, C.; Chudnovsky, E.M.; Garanin, D.A.

    2007-01-01

    We have studied direct and Raman processes of the decay of electron spin states in a quantum dot via radiation of phonons corresponding to elastic twists. Universal dependence of the spin relaxation rate on the strength and direction of the magnetic field has been obtained in terms of the electron gyromagnetic tensor and macroscopic elastic constants of the solid

  8. Relaxation of the electron spin in quantum dots via one- and two-phonon processes

    Energy Technology Data Exchange (ETDEWEB)

    Calero, C. [Department of Physics and Astronomy, Lehman College, City University of New York, 250 Bedford Park Boulevard West, Bronx, NY 10468-1589 (United States)]. E-mail: carlos.calero-borrallo@lehman.cuny.edu; Chudnovsky, E.M. [Department of Physics and Astronomy, Lehman College, City University of New York, 250 Bedford Park Boulevard West, Bronx, NY 10468-1589 (United States); Garanin, D.A. [Department of Physics and Astronomy, Lehman College, City University of New York, 250 Bedford Park Boulevard West, Bronx, NY 10468-1589 (United States)

    2007-09-15

    We have studied direct and Raman processes of the decay of electron spin states in a quantum dot via radiation of phonons corresponding to elastic twists. Universal dependence of the spin relaxation rate on the strength and direction of the magnetic field has been obtained in terms of the electron gyromagnetic tensor and macroscopic elastic constants of the solid.

  9. Probing Nuclear Spin Effects on Electronic Spin Coherence via EPR Measurements of Vanadium(IV) Complexes.

    Science.gov (United States)

    Graham, Michael J; Krzyaniak, Matthew D; Wasielewski, Michael R; Freedman, Danna E

    2017-07-17

    Quantum information processing (QIP) has the potential to transform numerous fields from cryptography, to finance, to the simulation of quantum systems. A promising implementation of QIP employs unpaired electronic spins as qubits, the fundamental units of information. Though molecular electronic spins offer many advantages, including chemical tunability and facile addressability, the development of design principles for the synthesis of complexes that exhibit long qubit superposition lifetimes (also known as coherence times, or T 2 ) remains a challenge. As nuclear spins in the local qubit environment are a primary cause of shortened superposition lifetimes, we recently conducted a study which employed a modular spin-free ligand scaffold to place a spin-laden propyl moiety at a series of fixed distances from an S = 1 / 2 vanadium(IV) ion in a series of vanadyl complexes. We found that, within a radius of 4.0(4)-6.6(6) Å from the metal center, nuclei did not contribute to decoherence. To assess the generality of this important design principle and test its efficacy in a different coordination geometry, we synthesized and investigated three vanadium tris(dithiolene) complexes with the same ligand set employed in our previous study: K 2 [V(C 5 H 6 S 4 ) 3 ] (1), K 2 [V(C 7 H 6 S 6 ) 3 ] (2), and K 2 [V(C 9 H 6 S 8 ) 3 ] (3). We specifically interrogated solutions of these complexes in DMF-d 7 /toluene-d 8 with pulsed electron paramagnetic resonance spectroscopy and electron nuclear double resonance spectroscopy and found that the distance dependence present in the previously synthesized vanadyl complexes holds true in this series. We further examined the coherence properties of the series in a different solvent, MeCN-d 3 /toluene-d 8 , and found that an additional property, the charge density of the complex, also affects decoherence across the series. These results highlight a previously unknown design principle for augmenting T 2 and open new pathways for the

  10. The use of electron spin resonance spectroscopy for the detection of irradiated shellfish and spices; Elektronenspinresonanz-spektroskopische Untersuchungen zur Identifizierung bestrahlter Krustentiere und Gewuerze: Durchfuehrung eines Ringversuches an Nordseekrabben, Kaisergranat und Paprikapulver

    Energy Technology Data Exchange (ETDEWEB)

    Helle, N. [Inst. fuer Sozialmedizin und Epidemiologie des Bundesgesundheitsamtes, Berlin (Germany); Linke, B. [Inst. fuer Sozialmedizin und Epidemiologie des Bundesgesundheitsamtes, Berlin (Germany); Boegl, K.W. [Inst. fuer Sozialmedizin und Epidemiologie des Bundesgesundheitsamtes, Berlin (Germany); Schreiber, G.A. [Inst. fuer Sozialmedizin und Epidemiologie des Bundesgesundheitsamtes, Berlin (Germany)

    1994-12-31

    A multilateral study on common shrimps, Norway lobster and paprika powder. The use of ESR spectroscopy in shellfish and some types of spice for the detection of previous irradiation is possible even on a routine basis. The radicals producing the specific ESR signals observed could at least in part be identified (CO{sup 2} radicals in shellfish, cellulose radicals in paprica) and the overall rate of correct classifications was seen to be very high for this multicentre study. The multicentre study has further been able to prove that previous reservations about ESR as a method of detection are no longer justified. The authors hold that there is no reason in principle why ESR should not be on the list of officially recommended methods for the examination of shellfish and spices according to paragraph35 LMBG. Nevertheless, the two groups of food at issue here need to be investigated in more detail in a number of further research projects, some of which are mentioned in the following: - investigations on further species of shellfish so as to obtain a broad range of spectra for routine controls; - structural identification of radiation-specific radicals generated in addition to the CO{sup 2} radical; - investigations into the influences of origin, time of fishing and stage of development on the ESR spectra of fishes; - examinations of further spices; - elucidation of links between cellulose contents and radical concentration. (orig./vhe) [Deutsch] Die Identifizierung bestrahlter Krustentiere und einiger bestrahlter Gewuerze mit Hilfe der ESR-Spektroskopie ist auch in der Routine moeglich. Die fuer die beobachteten spezifischen ESR-Signale verantwortlichen Radikale konnten zumindest teilweise identifiziert werden (CO{sup 2-} - Radikal bei Krustentieren, Cellulose-Radikal bei Paprika) und im Ringversuch wurde eine sehr hohe Quote richtiger Identifizierungen erreicht. Der Ringversuch hat zudem bewiesen, dass die bisher zur ESR-Methode geaeusserten prinzipiellen Bedenken

  11. Electron-spin-resonance techniques in fuel research

    Energy Technology Data Exchange (ETDEWEB)

    1965-06-01

    E.s.r. techniques provide a sensitive means of identifying the free radicals present in pyrolytic and combustion reactions, and determining their concentration. This article explains the theoretical basis of these techniques and indicates the scope of the work recently initiated with the e.s.r. spectrometer at the Division of Coal Research.

  12. Electron spin resonance dating of fault gouge from Desamangalam ...

    Indian Academy of Sciences (India)

    M. Senthilkumar (Newgen Imaging) 1461 1996 Oct 15 13:05:22

    R.S.I.C., Indian Institute of Technology, Powai, Mumbai 400 076, India .... Map showing linear structures of the area, prepared using satellite imagery, air photos and topographic maps. .... bags to avoid any loss of water and exposure to light.

  13. Electron spin resonance of Fe4+ in amethyst quartz

    International Nuclear Information System (INIS)

    Cox, R.T.

    1975-01-01

    The ESR spectrum of Fe 4+ was looked for in amethyst quartz. Besides saturated Fe 3+ lines, ESR lines of a new paramagnetic center whose spin-lattice relaxation time is relatively short were observed. They could be attributed to Fe 4+ [fr

  14. Dosimetry with alanine/electron spin resonance. Measuring and evaluating

    International Nuclear Information System (INIS)

    Anton, M.

    2007-02-01

    In the first part of the present report a short outline of the theoretical foundations in view of the parameters and evaluation programs described in the following is given. The second part described the measurement procedures and the handling of the measuring data including the applied data formats. In the third part the collection SPAD of MATLAB programs is described, which are necessary for the processing of the measurment data and the subsequent evaluations. Routine evaluations can by means of the present graphic user surface simply be performed. But the described routines can (and shall) be used also as kit in order to solve special evaluation problems. The third part closes with a listing of all programs including the online available aid texts. All functions were tested both under MATLAB 6 and under MATLAB 7

  15. Stern-Gerlach experiment, electron spin and intermediate quantum mechanics

    Energy Technology Data Exchange (ETDEWEB)

    Mackintosh, A.R. (Copenhagen Univ. (Denmark). H.C. Oersted Inst.)

    1983-01-01

    The paper deals with the theory of electron spin. The Stern-Gerlach experiment, the anticommutation relations and the properties of spin operators are discussed. The Pauli theory, Dirac transformation theory, the double Stern-Gerlach experiment, the EPR paradox and Bell's inequality are also covered.

  16. Electron spin transport in graphene and carbon nanotubes

    NARCIS (Netherlands)

    Tombros, Nikolaos

    2008-01-01

    Electron spin transport in grafeen en in koolstof nanobuisjes Grafeen, is een kristaal laag van koolstof atomen die slechts één atoomlaag dik is. Een koolstof nanobuisje is te verkrijgen door een grafeen laag op te rollen. In dit proefschrift laten we zien, met behulp van experimenten, dat deze

  17. Cavity Exciton-Polariton mediated, Single-Shot Quantum Non-Demolition measurement of a Quantum Dot Electron Spin

    Science.gov (United States)

    Puri, Shruti; McMahon, Peter; Yamamoto, Yoshihisa

    2014-03-01

    The quantum non-demolition (QND) measurement of a single electron spin is of great importance in measurement-based quantum computing schemes. The current single-shot readout demonstrations exhibit substantial spin-flip backaction. We propose a QND readout scheme for quantum dot (QD) electron spins in Faraday geometry, which differs from previous proposals and implementations in that it relies on a novel physical mechanism: the spin-dependent Coulomb exchange interaction between a QD spin and optically-excited quantum well (QW) microcavity exciton-polaritons. The Coulomb exchange interaction causes a spin-dependent shift in the resonance energy of the polarized polaritons, thus causing the phase and intensity response of left circularly polarized light to be different to that of the right circularly polarized light. As a result the QD electron's spin can be inferred from the response to a linearly polarized probe. We show that by a careful design of the system, any spin-flip backaction can be eliminated and a QND measurement of the QD electron spin can be performed within a few 10's of nanoseconds with fidelity 99:95%. This improves upon current optical QD spin readout techniques across multiple metrics, including fidelity, speed and scalability. National Institute of Informatics, 2-1-2 Hitotsubashi, Chiyoda-ku, Tokyo 101-8430, Japan.

  18. Control of electron spin decoherence in nuclear spin baths

    Science.gov (United States)

    Liu, Ren-Bao

    2011-03-01

    Nuclear spin baths are a main mechanism of decoherence of spin qubits in solid-state systems, such as quantum dots and nitrogen-vacancy (NV) centers of diamond. The decoherence results from entanglement between the electron and nuclear spins, established by quantum evolution of the bath conditioned on the electron spin state. When the electron spin is flipped, the conditional bath evolution is manipulated. Such manipulation of bath through control of the electron spin not only leads to preservation of the center spin coherence but also demonstrates quantum nature of the bath. In an NV center system, the electron spin effectively interacts with hundreds of 13 C nuclear spins. Under repeated flip control (dynamical decoupling), the electron spin coherence can be preserved for a long time (> 1 ms) . Thereforesomecharacteristicoscillations , duetocouplingtoabonded 13 C nuclear spin pair (a dimer), are imprinted on the electron spin coherence profile, which are very sensitive to the position and orientation of the dimer. With such finger-print oscillations, a dimer can be uniquely identified. Thus, we propose magnetometry with single-nucleus sensitivity and atomic resolution, using NV center spin coherence to identify single molecules. Through the center spin coherence, we could also explore the many-body physics in an interacting spin bath. The information of elementary excitations and many-body correlations can be extracted from the center spin coherence under many-pulse dynamical decoupling control. Another application of the preserved spin coherence is identifying quantumness of a spin bath through the back-action of the electron spin to the bath. We show that the multiple transition of an NV center in a nuclear spin bath can have longer coherence time than the single transition does, when the classical noises due to inhomogeneous broadening is removed by spin echo. This counter-intuitive result unambiguously demonstrates the quantumness of the nuclear spin bath

  19. Electron-Spin Precession in Dependence of the Orientation of the External Magnetic Field

    Directory of Open Access Journals (Sweden)

    Miah M

    2009-01-01

    Full Text Available Abstract Electron-spin dynamics in semiconductor-based heterostructures has been investigated in oblique magnetic fields. Spins are generated optically by a circularly polarized light, and the dynamics of spins in dependence of the orientation (θ of the magnetic field are studied. The electron-spin precession frequency, polarization amplitude, and decay rate as a function ofθare obtained and the reasons for their dependences are discussed. From the measured data, the values of the longitudinal and transverse components of the electrong-factor are estimated and are found to be in good agreement with those obtained in earlier investigations. The possible mechanisms responsible for the observed effects are also discussed.

  20. Electron spin-lattice relaxation in fractals

    International Nuclear Information System (INIS)

    Shrivastava, K.N.

    1986-08-01

    We have developed the theory of the spin-fracton interaction for paramagnetic ions in fractal structures. The interaction is exponentially damped by the self-similarity length of the fractal and by the range dimensionality d Φ . The relaxation time of the spin due to the absorption and emission of the fracton has been calculated for a general dimensionality called the Raman dimensionality d R , which for the fractons differs from the Hausdorff (fractal) dimensionality, D, as well as from the Euclidean dimensionality, d. The exponent of the energy level separation in the relaxation rate varies with d R d Φ /D. We have calculated the spin relaxation rate due to a new type of Raman process in which one fracton is absorbed to affect a spin transition from one electronic level to another and later another fracton is emitted along with a spin transition such that the difference in the energies of the two fractons is equal to the electronic energy level separation. The temperature and the dimensionality dependence of such a process has been found in several approximations. In one of the approximations where the van Vleck relaxation rate for a spin in a crystal is known to vary with temperature as T 9 , our calculated variation for fractals turns out to be T 6.6 , whereas the experimental value for Fe 3+ in frozen solutions of myoglobin azide is T 6.3 . Since we used d R =4/3 and the fracton range dimensionality d Φ =D/1.8, we expect to measure the dimensionalities of the problem by measuring the temperature dependence of the relaxation times. We have also calculated the shift of the paramagnetic resonance transition for a spin in a fractal for general dimensionalities. (author)

  1. Frequency bandwidth extension by use of multiple Zeeman field offsets for electron spin-echo EPR oxygen imaging of large objects

    Science.gov (United States)

    Seifi, Payam; Epel, Boris; Sundramoorthy, Subramanian V.; Mailer, Colin; Halpern, Howard J.

    2011-01-01

    Purpose: Electron spin-echo (ESE) oxygen imaging is a new and evolving electron paramagnetic resonance (EPR) imaging (EPRI) modality that is useful for physiological in vivo applications, such as EPR oxygen imaging (EPROI), with potential application to imaging of multicentimeter objects as large as human tumors. A present limitation on the size of the object to be imaged at a given resolution is the frequency bandwidth of the system, since the location is encoded as a frequency offset in ESE imaging. The authors’ aim in this study was to demonstrate the object size advantage of the multioffset bandwidth extension technique.Methods: The multiple-stepped Zeeman field offset (or simply multi-B) technique was used for imaging of an 8.5-cm-long phantom containing a narrow single line triaryl methyl compound (trityl) solution at the 250 MHz imaging frequency. The image is compared to a standard single-field ESE image of the same phantom.Results: For the phantom used in this study, transverse relaxation (T2e) electron spin-echo (ESE) images from multi-B acquisition are more uniform, contain less prominent artifacts, and have a better signal to noise ratio (SNR) compared to single-field T2e images.Conclusions: The multi-B method is suitable for imaging of samples whose physical size restricts the applicability of the conventional single-field ESE imaging technique. PMID:21815379

  2. Electron Spin Coherence Times in Si/SiGe Quantum Dots

    Science.gov (United States)

    Jock, R. M.; He, Jianhua; Tyryshkin, A. M.; Lyon, S. A.; Lee, C.-H.; Huang, S.-H.; Liu, C. W.

    2014-03-01

    Single electron spin states in silicon have shown a great deal of promise as qubits due to their long spin relaxation (T1) and coherence (T2) times. Recent results exhibit a T2 of 250 us for electrons confined in Si/SiGe quantum dots at 350 mK. These experiments used conventional X-band (10 GHz) pulsed Electron Spin Resonance on a large area (3.5 mm x 20 mm), dual-gated, undoped Si/SiGe heterostructure quantum dots. These dots are induced in a natural Si quantum well by e-beam defined gates having a lithographic radius of 150 nm and pitch of 700 nm. The relatively large size of these dots led to closely spaced energy levels and long T2's could only be measured at sub-Kelvin temperatures. At 2K confined electrons displayed a 3 us T2, which is comparable to that of 2D electrons at that temperature. Decreasing the quantum dot size increases the electron confinement and reduces the effects of valley-splitting and spin-orbit coupling on the electron spin coherence times. We will report results on dots with 80 nm lithographic radii and a 375 nm pitch. This device displays an extended electron coherence time of 30 us at 2K, suggesting tighter confinement of electrons. Further measurements at lower temperatures are in progress. This work was supported in part by NSF through the Materials World Network program (DMR-1107606) and the Princeton MRSEC (DMR-0819860), and in part by the U.S. Army Research Office (W911NF-13-1-0179).

  3. Proton capture resonance studies

    Energy Technology Data Exchange (ETDEWEB)

    Mitchell, G.E. [North Carolina State University, Raleigh, North Carolina (United States) 27695]|[Triangle Universities Nuclear Laboratory, Durham, North Carolina (United States) 27708; Bilpuch, E.G. [Duke University, Durham, North Carolina (United States) 27708]|[Triangle Universities Nuclear Laboratory, Durham, North Carolina (United States) 27708; Bybee, C.R. [North Carolina State University, Raleigh, North Carolina (United States) 27695]|[Triangle Universities Nuclear Laboratory, Durham, North Carolina (United States) 27708; Cox, J.M.; Fittje, L.M. [Tennessee Technological University, Cookeville, Tennessee (United States) 38505]|[Triangle Universities Nuclear Laboratory, Durham, North Carolina (United States) 27708; Labonte, M.A.; Moore, E.F.; Shriner, J.D. [North Carolina State University, Raleigh, North Carolina (United States) 27695]|[Triangle Universities Nuclear Laboratory, Durham, North Carolina (United States) 27708; Shriner, J.F. Jr. [Tennessee Technological University, Cookeville, Tennessee (United States) 38505]|[Triangle Universities Nuclear Laboratory, Durham, North Carolina (United States) 27708; Vavrina, G.A. [North Carolina State University, Raleigh, North Carolina (United States) 27695]|[Triangle Universities Nuclear Laboratory, Durham, North Carolina (United States) 27708; Wallace, P.M. [Duke University, Durham, North Carolina (United States) 27708]|[Triangle Universities Nuclear Laboratory, Durham, North Carolina (United States) 27708

    1997-02-01

    The fluctuation properties of quantum systems now are used as a signature of quantum chaos. The analyses require data of extremely high quality. The {sup 29}Si(p,{gamma}) reaction is being used to establish a complete level scheme of {sup 30}P to study chaos and isospin breaking in this nuclide. Determination of the angular momentum J, the parity {pi}, and the isospin T from resonance capture data is considered. Special emphasis is placed on the capture angular distributions and on a geometric description of these angular distributions. {copyright} {ital 1997 American Institute of Physics.}

  4. Towards the Rational Design of MRI Contrast Agents: Electron Spin Relaxation Is Largely Unaffected by the Coordination Geometry of Gadolinium(III)–DOTA-Type Complexes

    Science.gov (United States)

    Bean, Jonathan F.; Clarkson, Robert B.; Helm, Lothar; Moriggi, Loïck; Sherry, A. Dean

    2009-01-01

    Electron-spin relaxation is one of the determining factors in the efficacy of MRI contrast agents. Of all the parameters involved in determining relaxivity it remains the least well understood, particularly as it relates to the structure of the complex. One of the reasons for the poor understanding of electron-spin relaxation is that it is closely related to the ligand-field parameters of the Gd3+ ion that forms the basis of MRI contrast agents and these complexes generally exhibit a structural isomerism that inherently complicates the study of electron spin relaxation. We have recently shown that two DOTA-type ligands could be synthesised that, when coordinated to Gd3+, would adopt well defined coordination geometries and are not subject to the problems of intramolecular motion of other complexes. The EPR properties of these two chelates were studied and the results examined with theory to probe their electron-spin relaxation properties. PMID:18283704

  5. Electron spin resonance studies of γ-irradiated phosphite and phosphate esters. Identification of phosphinyl, phosphonyl, phosphoranyl, and phosphine dimer cation radicals

    International Nuclear Information System (INIS)

    Kerr, C.M.L.; Webster, K.; Williams, F.

    1975-01-01

    The powder ESR spectra of several γ-irradiated phosphorus esters at 77 0 K were analyzed into their distinguishable radical components, each spectrum being generally a composite of anisotropic features from a number of alkyl and phosphorus-centered radicals. Resolution of overlapping spectra was achieved in some instances by radiation-chemical experiments designed to suppress or enhance the products of electron capture relative to the radicals formed by other mechanisms. The radiation chemistry of dialkyl phosphites, (RO) 2 P(O)H, is influenced by the ease with which the P--H bond in these compounds is broken, the principal radicals being the phosphonyl species (RO) 2 PO and ROP(O)O - . Both of these species are thought to be the secondary products of hydrogen atom abstraction by the alkyl radical R which is produced by dissociative electron capture. A similar primary step was found to apply for the trialkyl phosphates, (RO) 3 PO, but in this case only carbon-centered radicals are formed by secondary H-atom abstraction processes. Results for the pyrophosphite differ from those for the trialkyl phosphites in showing the absence of alkyl radicals or their phosphoranyl adducts and the formation of the phosphonyl species (EtO) 2 PO, the latter being produced presumably by cleavage of the P--O--P bridge. The ESR parameters for each of the four main groups of phosphorus-centered radicals are summarized and the electronic structures of these radicals are discussed briefly

  6. Charge recombination process in X-ray irradiated pyrene-doped polystyrene as studied by optically detected electron spin resonance and magnetic field dependence of the recombination fluorescence

    International Nuclear Information System (INIS)

    Okazaki, Masaharu; Tai, Yutaka; Toriyama, Kazumi

    1993-01-01

    The optically-detected ESR (ODESR) spectrum and magnetic field dependence on recombination fluorescence were observed for X-ray irradiated pyrene-doped polystyrene at temperatures of 242-348 K. The ODESR intensity as a function of the pyrene concentration, 0.1-8.9 wt%, showed an unusual minimum at about 1.0%. Two phases were separated in the magnetic field dependence of the fluorescence: one was sharp and saturates at fields of over 50 mT, while the other was broad with a dip at around 60-150 mT. The cause of this dip was naturally attributed to the ST -1 level crossing. The sharp magnetic field effect also showed a minimum at around a concentration of 1.0 wt%. These novel findings have been interpreted using a recombination model modified from the previous one for pyrene-doped ethylene-propylene rubber and polyethylene. The essential points of the present model are: (1) although electron hopping within the polystyrene molecule is rapid, electron transfer at the last step of recombination between the polystyrene anion and the pyrene cation proceeds at a moderate rate; (2) the hole-transfer rate in the polymer chain is moderate; (3) electron hopping between the doped pyrene molecules is very much dependent on the concentration; (4) hole hopping between the pyrenes is inhibited. (author)

  7. Foucault's pendulum, a classical analog for the electron spin state

    Science.gov (United States)

    Linck, Rebecca A.

    Spin has long been regarded as a fundamentally quantum phenomena that is incapable of being described classically. To bridge the gap and show that aspects of spin's quantum nature can be described classically, this work uses a classical Lagrangian based on the coupled oscillations of Foucault's pendulum as an analog for the electron spin state in an external magnetic field. With this analog it is possible to demonstrate that Foucault's pendulum not only serves as a basis for explaining geometric phase, but is also a basis for reproducing a broad range of behavior from Zeeman-like frequency splitting to precession of the spin state. By demonstrating that unmeasured electron spin states can be fully described in classical terms, this research opens the door to using the tools of classical physics to examine an inherently quantum phenomenon.

  8. Electron Spin Optical Orientation in Charged Quantum Dots

    Science.gov (United States)

    Shabaev, A.; Gershoni, D.; Korenev, V. L.

    2005-03-01

    We present a theory of nonresonant optical orientation of electron spins localized in quantum dots. This theory explains the negative circularly polarized photoluminescence of singlet trions localized in quantum dots previously observed in experiments where trion polarization changed to negative with time and where the degree of the negative polarization increased with intensity of pumping light. We have shown that this effect can be explained by the accumulation of dark excitons that occurs due to the spin blocking of the singlet trion formation - the major mechanism of dark exciton recombination. The accumulation of dark excitons results from a lack of electrons with a spin matching the exciton polarization. The electron spin lifetime is shortened by a transverse magnetic field or a temperature increase. This takes the block off the dark exciton recombination and restores the positive degree of trion polarization. The presented theory gives good agreement with experimental data.

  9. High field electron-spin transport and observation of the Dyakonov-Perel spin relaxation of drifting electrons in low temperature-grown gallium arsenide

    International Nuclear Information System (INIS)

    Miah, M. Idrish

    2008-01-01

    High field electron-spin transport in low temperature-grown gallium arsenide is studied. We generate electron spins in the samples by optical pumping. During transport, we observe the Dyakonov-Perel (DP) [M.I. Dyakonov, V.I. Perel, Zh. Eksp. Teor. Fiz. 60 (1971) 1954] spin relaxation of the drifting electrons. The results are discussed and are compared with those obtained in calculations of the DP spin relaxation frequency of the hot electrons. A good agreement is obtained

  10. High field electron-spin transport and observation of the Dyakonov-Perel spin relaxation of drifting electrons in low temperature-grown gallium arsenide

    Energy Technology Data Exchange (ETDEWEB)

    Miah, M. Idrish [Nanoscale Science and Technology Centre, Griffith University, Nathan, Brisbane, QLD 4111 (Australia); Biomolecular and Physical Sciences, Griffith University, Nathan, Brisbane, QLD 4111 (Australia); Department of Physics, University of Chittagong, Chittagong-4331 (Bangladesh)], E-mail: m.miah@griffith.edu.au

    2008-11-17

    High field electron-spin transport in low temperature-grown gallium arsenide is studied. We generate electron spins in the samples by optical pumping. During transport, we observe the Dyakonov-Perel (DP) [M.I. Dyakonov, V.I. Perel, Zh. Eksp. Teor. Fiz. 60 (1971) 1954] spin relaxation of the drifting electrons. The results are discussed and are compared with those obtained in calculations of the DP spin relaxation frequency of the hot electrons. A good agreement is obtained.

  11. Inhomogeneous nuclear spin polarization induced by helicity-modulated optical excitation of fluorine-bound electron spins in ZnSe

    Science.gov (United States)

    Heisterkamp, F.; Greilich, A.; Zhukov, E. A.; Kirstein, E.; Kazimierczuk, T.; Korenev, V. L.; Yugova, I. A.; Yakovlev, D. R.; Pawlis, A.; Bayer, M.

    2015-12-01

    Optically induced nuclear spin polarization in a fluorine-doped ZnSe epilayer is studied by time-resolved Kerr rotation using resonant excitation of donor-bound excitons. Excitation with helicity-modulated laser pulses results in a transverse nuclear spin polarization, which is detected as a change of the Larmor precession frequency of the donor-bound electron spins. The frequency shift in dependence on the transverse magnetic field exhibits a pronounced dispersion-like shape with resonances at the fields of nuclear magnetic resonance of the constituent zinc and selenium isotopes. It is studied as a function of external parameters, particularly of constant and radio frequency external magnetic fields. The width of the resonance and its shape indicate a strong spatial inhomogeneity of the nuclear spin polarization in the vicinity of a fluorine donor. A mechanism of optically induced nuclear spin polarization is suggested based on the concept of resonant nuclear spin cooling driven by the inhomogeneous Knight field of the donor-bound electron.

  12. Non-conventional ordering studied by magnetic resonance in Fe-doped manganites

    International Nuclear Information System (INIS)

    Gutierrez, J.; Siruguri, V.; Barandiaran, J.M.; Pena, A.; Lezama, L.; Rojo, T.

    2006-01-01

    Coexistence of ferromagnetic (FM) and paramagnetic (PM) phases in La 0.7 Pb 0.3 (Mn 1-x Fe x )O 3 (0.1=< x=<0.3) manganites is studied by the electron spin resonance (ESR) technique. Doping with Fe gives rise to a progressive decrease both in the low-temperature magnetic moment and magnetic order temperature values. Obtained spectra show narrow resonance signals above Curie temperature that transform to asymmetric Dyson-like signals as temperature decreases. The evolution of line width with temperature shows minima that correlate directly with the obtained paramagnetic Curie temperatures. Analysis of spectra above and below magnetic order temperatures reveals features of complex PM to FM transitions and coexistence of both type of phases in a wide range of temperatures

  13. ESR spectrometer with a loop-gap resonator for cw and time resolved studies in a superconducting magnet.

    Science.gov (United States)

    Simon, Ferenc; Murányi, Ferenc

    2005-04-01

    The design and performance of an electron spin resonance spectrometer operating at 3 and 9 GHz microwave frequencies combined with a 9-T superconducting magnet are described. The probehead contains a compact two-loop, one gap resonator, and is inside the variable temperature insert of the magnet enabling measurements in the 0-9T magnetic field and 1.5-400 K temperature range. The spectrometer allows studies on systems where resonance occurs at fields far above the g approximately 2 paramagnetic condition such as in antiferromagnets. The low quality factor of the resonator allows time resolved experiments such as, e.g., longitudinally detected ESR. We demonstrate the performance of the spectrometer on the NaNiO2 antiferromagnet, the MgB2 superconductor, and the RbC60 conducting alkaline fulleride polymer.

  14. Foucault's Pendulum, Analog for an Electron Spin State

    Science.gov (United States)

    Linck, Rebecca

    2012-11-01

    The classical Lagrangian that describes the coupled oscillations of Foucault's pendulum presents an interesting analog to an electron's spin state in an external magnetic field. With a simple modification, this classical Lagrangian yields equations of motion that directly map onto the Schrodinger-Pauli Equation. This analog goes well beyond the geometric phase, reproducing a broad range of behavior from Zeeman-like frequency splitting to precession of the spin state. By demonstrating that unmeasured spin states can be fully described in classical terms, this research opens the door to using the tools of classical physics to examine an inherently quantum phenomenon.

  15. POLARIZED BEAMS: 1 - Longitudinal electron spin polarization at HERA

    Energy Technology Data Exchange (ETDEWEB)

    Anon.

    1994-09-15

    Wednesday 4 May marked a turning point in the art of the manipulation of spins in electron storage rings: longitudinal electron spin polarization (with the spins oriented along the electrons' direction of motion) was established in the electron ring of HERA, the electronproton collider at DESY in Hamburg. A polarization level of about 55% was obtained and polarizations of over 60% were reproducibly obtained in the following days. The beam energy was 27.52 GeV, corresponding to half integer spin tune of 62.5.

  16. High-fidelity adiabatic inversion of a {sup 31}P electron spin qubit in natural silicon

    Energy Technology Data Exchange (ETDEWEB)

    Laucht, Arne, E-mail: a.laucht@unsw.edu.au; Kalra, Rachpon; Muhonen, Juha T.; Dehollain, Juan P.; Mohiyaddin, Fahd A.; Hudson, Fay; Dzurak, Andrew S.; Morello, Andrea [Centre for Quantum Computation and Communication Technology, School of Electrical Engineering and Telecommunications, University of New South Wales, Sydney, New South Wales 2052 (Australia); McCallum, Jeffrey C.; Jamieson, David N. [Centre for Quantum Computation and Communication Technology, School of Physics, University of Melbourne, Melbourne, Victoria 3010 (Australia)

    2014-03-03

    The main limitation to the high-fidelity quantum control of spins in semiconductors is the presence of strongly fluctuating fields arising from the nuclear spin bath of the host material. We demonstrate here a substantial improvement in single-qubit inversion fidelities for an electron spin qubit bound to a {sup 31}P atom in natural silicon, by applying adiabatic sweeps instead of narrow-band pulses. We achieve an inversion fidelity of 97%, and we observe signatures in the spin resonance spectra and the spin coherence time that are consistent with the presence of an additional exchange-coupled donor. This work highlights the effectiveness of simple adiabatic inversion techniques for spin control in fluctuating environments.

  17. Contribution of vitamin K1 to the electron spin polarization in spinach photosystem I

    International Nuclear Information System (INIS)

    Rustandi, R.R.; Snyder, S.W.; Feezel, L.L.; Michalski, T.J.; Norris, J.R.; Thurnauer, M.C.; Biggins, J.

    1990-01-01

    The electron spin polarized (ESP) electron paramagnetic resonance (EPR) signal observed in spinach photosystem I (PSI) particles was examined in preparations depleted of vitamin K1 by solvent extraction and following biological reconstitution by the quinone. The ESP EPR signal was not detected in the solvent-extracted PSI sample but was restored upon reconstitution with either protonated or deuterated vitamin K1 under conditions that also restored electron transfer to the terminal PSI acceptors. Reconstitution using deuterated vitamin K1 resulted in a line narrowing of the ESP EPR signal, supporting the conclusion that the ESP EPR signals in the reconstituted samples arise from a radical pair consisting of the oxidized PSI primary donor, P700+, and reduced vitamin K1

  18. Comparison of 250 MHz electron spin echo and continuous wave oxygen EPR imaging methods for in vivo applications

    Science.gov (United States)

    Epel, Boris; Sundramoorthy, Subramanian V.; Barth, Eugene D.; Mailer, Colin; Halpern, Howard J.

    2011-01-01

    Purpose: The authors compare two electron paramagnetic resonance imaging modalities at 250 MHz to determine advantages and disadvantages of those modalities for in vivo oxygen imaging. Methods: Electron spin echo (ESE) and continuous wave (CW) methodologies were used to obtain three-dimensional images of a narrow linewidth, water soluble, nontoxic oxygen-sensitive trityl molecule OX063 in vitro and in vivo. The authors also examined sequential images obtained from the same animal injected intravenously with trityl spin probe to determine temporal stability of methodologies. Results: A study of phantoms with different oxygen concentrations revealed a threefold advantage of the ESE methodology in terms of reduced imaging time and more precise oxygen resolution for samples with less than 70 torr oxygen partial pressure. Above∼100 torr, CW performed better. The images produced by both methodologies showed pO2 distributions with similar mean values. However, ESE images demonstrated superior performance in low pO2 regions while missing voxels in high pO2 regions. Conclusions: ESE and CW have different areas of applicability. ESE is superior for hypoxia studies in tumors. PMID:21626937

  19. Electron spin ressonance of radicals produced by ultra-violet photolysis of KCL dopped with potassium cyanide and potassium cyanate

    International Nuclear Information System (INIS)

    Duran, J.E.R.

    1975-01-01

    The production of radicals by ultra-violet photolysis of KCL dopped with potassium cyanide and potassium cyanate is studied by electron spin resonance. Several new paramagnetic species are detected which are identified as HCNO - , NCN - /NCNO - , CNN - /CNON - and CNOsup(=) all giving isotropic spectra at 77 0 K. The temperature dependence of the CNOsup(=) spectrum is investigated down to 1.6 0 K. It is found that two different recrientation motions ocurr which freeze at different temperatures. The effect of this motion on the line width is analized using Anderson's theory of exchange narrowing. The electronic structure of the CNOsup(=) radical is discussed using the measured the carbon and nitrogen hfs constants. It is found that a bonding scheme similar to that accepted for the isoelectronic molecule NO 2 is applicable, and a one electron molecular orbital scheme is given. Within this scheme a negative contribution to the nitrogen isotropic hfs constant is found which is assumed to originate from the polarization of the fully occupied ls orbitals [pt

  20. Optically pumped electron spin polarized targets for use in the production of polarized ion beams

    International Nuclear Information System (INIS)

    Anderson, L.W.

    1979-01-01

    The production of relatively dense electron spin polarized alkali metal vapor targets by optical pumping with intense cw dye lasers is discussed. The target density and electron spin polarization depend on the dye laser intensity and bandwidth, the magnetic field at the target, and the electron spin depolarization time. For example in a magnetic field of 1.5 x 10 3 G, and using 1 W dye laser with a bandwidth of 10 10 Hz one can construct an electron spin polarized Na vapor target with a target thickness of 1.6 x 10 13 atoms/cm 2 and an average electron spin polarization of about 90% even though the Na atoms are completely depolarized at every wall collision. Possible uses of the electron spin polarized targets for the production of intense beams of polarized H - or 3 He - ions are discussed. (orig.)

  1. Spin–orbit induced electronic spin separation in semiconductor nanostructures

    Science.gov (United States)

    Kohda, Makoto; Nakamura, Shuji; Nishihara, Yoshitaka; Kobayashi, Kensuke; Ono, Teruo; Ohe, Jun-ichiro; Tokura, Yasuhiro; Mineno, Taiki; Nitta, Junsaku

    2012-01-01

    The demonstration of quantized spin splitting by Stern and Gerlach is one of the most important experiments in modern physics. Their discovery was the precursor of recent developments in spin-based technologies. Although electrical spin separation of charged particles is fundamental in spintronics, in non-uniform magnetic fields it has been difficult to separate the spin states of charged particles due to the Lorentz force, as well as to the insufficient and uncontrollable field gradients. Here we demonstrate electronic spin separation in a semiconductor nanostructure. To avoid the Lorentz force, which is inevitably induced when an external magnetic field is applied, we utilized the effective non-uniform magnetic field which originates from the Rashba spin–orbit interaction in an InGaAs-based heterostructure. Using a Stern–Gerlach-inspired mechanism, together with a quantum point contact, we obtained field gradients of 108 T m−1 resulting in a highly polarized spin current. PMID:23011136

  2. Spin-orbit induced electronic spin separation in semiconductor nanostructures.

    Science.gov (United States)

    Kohda, Makoto; Nakamura, Shuji; Nishihara, Yoshitaka; Kobayashi, Kensuke; Ono, Teruo; Ohe, Jun-ichiro; Tokura, Yasuhiro; Mineno, Taiki; Nitta, Junsaku

    2012-01-01

    The demonstration of quantized spin splitting by Stern and Gerlach is one of the most important experiments in modern physics. Their discovery was the precursor of recent developments in spin-based technologies. Although electrical spin separation of charged particles is fundamental in spintronics, in non-uniform magnetic fields it has been difficult to separate the spin states of charged particles due to the Lorentz force, as well as to the insufficient and uncontrollable field gradients. Here we demonstrate electronic spin separation in a semiconductor nanostructure. To avoid the Lorentz force, which is inevitably induced when an external magnetic field is applied, we utilized the effective non-uniform magnetic field which originates from the Rashba spin-orbit interaction in an InGaAs-based heterostructure. Using a Stern-Gerlach-inspired mechanism, together with a quantum point contact, we obtained field gradients of 10(8) T m(-1) resulting in a highly polarized spin current.

  3. Coupling a Surface Acoustic Wave to an Electron Spin in Diamond via a Dark State

    Directory of Open Access Journals (Sweden)

    D. Andrew Golter

    2016-12-01

    Full Text Available The emerging field of quantum acoustics explores interactions between acoustic waves and artificial atoms and their applications in quantum information processing. In this experimental study, we demonstrate the coupling between a surface acoustic wave (SAW and an electron spin in diamond by taking advantage of the strong strain coupling of the excited states of a nitrogen vacancy center while avoiding the short lifetime of these states. The SAW-spin coupling takes place through a Λ-type three-level system where two ground spin states couple to a common excited state through a phonon-assisted as well as a direct dipole optical transition. Both coherent population trapping and optically driven spin transitions have been realized. The coherent population trapping demonstrates the coupling between a SAW and an electron spin coherence through a dark state. The optically driven spin transitions, which resemble the sideband transitions in a trapped-ion system, can enable the quantum control of both spin and mechanical degrees of freedom and potentially a trapped-ion-like solid-state system for applications in quantum computing. These results establish an experimental platform for spin-based quantum acoustics, bridging the gap between spintronics and quantum acoustics.

  4. Electron spin echo envelope modulation (ESEEM) reveals water and phosphate interactions with the KcsA potassium channel

    OpenAIRE

    Cieslak, John A.; Focia, Pamela J.; Gross, Adrian

    2010-01-01

    Electron spin-echo envelope modulation (ESEEM) spectroscopy is a well-established technique for the study of naturally occurring paramagnetic metal centers. The technique has been used to study copper complexes, hemes, enzyme mechanisms, micellar water content, and water permeation profiles in membranes, among other applications. In the present study, we combine ESEEM spectroscopy with site-directed spin labeling (SDSL) and X-ray crystallography in order to evaluate the technique's potential ...

  5. Investigations on resolution enhancement in EPR by means of electron spin echoes

    International Nuclear Information System (INIS)

    Merks, R.P.J.

    1979-01-01

    The electron spin echo technique has been applied in four types of experiments: the measurement of electric field induced shifts of the EPR line; the detection of electron spin echo ENDOR; a relaxation measurement and the measurement of hyperfine interactions via the nuclear modulation effect. (Auth.)

  6. Pulse-based electron spin transient nutation measurement of BaTiO3 fine particle: Identification of controversial signal around g = 2.00

    Science.gov (United States)

    Sawai, Takatoshi; Yamaguchi, Yoji; Kitamura, Noriko; Date, Tomotsugu; Konishi, Shinya; Taga, Kazuya; Tanaka, Katsuhisa

    2018-05-01

    Two dimensional pulse-based electron spin transient nutation (2D-ESTN) spectroscopy is a powerful tool for determining the spin quantum number and has been applied to BaTiO3 fine powder in order to identify the origin of the continuous wave electron spin resonance (CW-ESR) signal around g = 2.00. The signal is frequently observed in BaTiO3 ceramics, and the correlation between the signal intensity and positive temperature coefficient of resistivity (PTCR) properties has been reported to date. The CW-ESR spectrum of BaTiO3 fine particles synthesized by the sol-gel method shows a typical asymmetric signal at g = 2.004. The 2D-ESTN measurements of the sample clearly reveal that the signal belongs to the S = 5/2 high spin state, indicating that the signal is not due to a point defect as suggested by a number of researchers but rather to a transition metal ion. Our elemental analysis, as well as previous studies, indicates that the origin of the g = 2.004 signal is due to the presence of an Fe3+ impurity. The D value (second-order fine structure parameter) reveals that the origin of the signal is an Fe3+ center with distant charge compensation. In addition, we show a peculiar temperature dependence of the CW-ESR spectrum, suggesting that the phase transition behavior of a BaTiO3 fine particle is quite different from that of a bulk single crystal. Our identification does not contradict a vacancy-mediated mechanism for PTCR. However, it is incorrect to use the signal at g = 2.00 as evidence to support the vacancy-mediated mechanism.

  7. Electron spin relaxation in a transition-metal dichalcogenide quantum dot

    Science.gov (United States)

    Pearce, Alexander J.; Burkard, Guido

    2017-06-01

    We study the relaxation of a single electron spin in a circular quantum dot in a transition-metal dichalcogenide monolayer defined by electrostatic gating. Transition-metal dichalcogenides provide an interesting and promising arena for quantum dot nano-structures due to the combination of a band gap, spin-valley physics and strong spin-orbit coupling. First we will discuss which bound state solutions in different B-field regimes can be used as the basis for qubits states. We find that at low B-fields combined spin-valley Kramers qubits to be suitable, while at large magnetic fields pure spin or valley qubits can be envisioned. Then we present a discussion of the relaxation of a single electron spin mediated by electron-phonon interaction via various different relaxation channels. In the low B-field regime we consider the spin-valley Kramers qubits and include impurity mediated valley mixing which will arise in disordered quantum dots. Rashba spin-orbit admixture mechanisms allow for relaxation by in-plane phonons either via the deformation potential or by piezoelectric coupling, additionally direct spin-phonon mechanisms involving out-of-plane phonons give rise to relaxation. We find that the relaxation rates scale as \\propto B 6 for both in-plane phonons coupling via deformation potential and the piezoelectric effect, while relaxation due to the direct spin-phonon coupling scales independant to B-field to lowest order but depends strongly on device mechanical tension. We will also discuss the relaxation mechanisms for pure spin or valley qubits formed in the large B-field regime.

  8. Electronic Spin Storage in an Electrically Readable Nuclear Spin Memory with a Lifetime >100 Seconds

    Science.gov (United States)

    McCamey, D. R.; Van Tol, J.; Morley, G. W.; Boehme, C.

    2010-12-01

    Electron spins are strong candidates with which to implement spintronics because they are both mobile and able to be manipulated. The relatively short lifetimes of electron spins, however, present a problem for the long-term storage of spin information. We demonstrated an ensemble nuclear spin memory in phosphorous-doped silicon, which can be read out electrically and has a lifetime exceeding 100 seconds. The electronic spin information can be mapped onto and stored in the nuclear spin of the phosphorus donors, and the nuclear spins can then be repetitively read out electrically for time periods that exceed the electron spin lifetime. We discuss how this memory can be used in conjunction with other silicon spintronic devices.

  9. Multiphoton electronic-spin generation and transmission spectroscopy in n-type GaAs

    Energy Technology Data Exchange (ETDEWEB)

    Idrish Miah, M., E-mail: m.miah@griffith.edu.a [Department of Physics, University of Chittagong, Chittagong 4331 (Bangladesh)

    2011-01-17

    Multiphoton electronic-spin generation in semiconductors was investigated using differential transmission spectroscopy. The generation of the electronic spins in the semiconductor samples were achieved by multiphoton pumping with circularly polarized light beam and was probed by the spin-resolved transmission of the samples. The electronic spin-polarization of conduction band was estimated and was found to depend on the delay of the probe beam, temperature as well as on the multiphoton pumping energy. The temperature dependence showed a decrease of the spin-polarization with increasing temperature. The electronic spin-polarization was found to depolarize rapidly for multiphoton pumping energy larger than the energy gap of the split-off band to the conduction band. The results were compared with those obtained in one-photon pumping, which shows that an enhancement of the electronic spin-polarization was achieved in multiphoton pumping. The findings resulting from this investigation might have potential applications in opto-spintronics, where the generation of highly polarized electronic spins is required.

  10. Multiphoton electronic-spin generation and transmission spectroscopy in n-type GaAs

    International Nuclear Information System (INIS)

    Idrish Miah, M.

    2011-01-01

    Multiphoton electronic-spin generation in semiconductors was investigated using differential transmission spectroscopy. The generation of the electronic spins in the semiconductor samples were achieved by multiphoton pumping with circularly polarized light beam and was probed by the spin-resolved transmission of the samples. The electronic spin-polarization of conduction band was estimated and was found to depend on the delay of the probe beam, temperature as well as on the multiphoton pumping energy. The temperature dependence showed a decrease of the spin-polarization with increasing temperature. The electronic spin-polarization was found to depolarize rapidly for multiphoton pumping energy larger than the energy gap of the split-off band to the conduction band. The results were compared with those obtained in one-photon pumping, which shows that an enhancement of the electronic spin-polarization was achieved in multiphoton pumping. The findings resulting from this investigation might have potential applications in opto-spintronics, where the generation of highly polarized electronic spins is required.

  11. High-Resolution Two-Dimensional Optical Spectroscopy of Electron Spins

    Directory of Open Access Journals (Sweden)

    M. Salewski

    2017-08-01

    Full Text Available Multidimensional coherent optical spectroscopy is one of the most powerful tools for investigating complex quantum mechanical systems. While it was conceived decades ago in magnetic resonance spectroscopy using microwaves and radio waves, it has recently been extended into the visible and UV spectral range. However, resolving MHz energy splittings with ultrashort laser pulses still remains a challenge. Here, we analyze two-dimensional Fourier spectra for resonant optical excitation of resident electrons to localized trions or donor-bound excitons in semiconductor nanostructures subject to a transverse magnetic field. Particular attention is devoted to Raman coherence spectra, which allow one to accurately evaluate tiny splittings of the electron ground state and to determine the relaxation times in the electron spin ensemble. A stimulated steplike Raman process induced by a sequence of two laser pulses creates a coherent superposition of the ground-state doublet which can be retrieved only optically because of selective excitation of the same subensemble with a third pulse. This provides the unique opportunity to distinguish between different complexes that are closely spaced in energy in an ensemble. The related experimental demonstration is based on photon-echo measurements in an n-type CdTe/(Cd,MgTe quantum-well structure detected by a heterodyne technique. The difference in the sub-μeV range between the Zeeman splittings of donor-bound electrons and electrons localized at potential fluctuations can be resolved even though the homogeneous linewidth of the optical transitions is larger by 2 orders of magnitude.

  12. Electron-spin dynamics in Mn-doped GaAs using time-resolved magneto-optical techniques

    Science.gov (United States)

    Akimov, I. A.; Dzhioev, R. I.; Korenev, V. L.; Kusrayev, Yu. G.; Zhukov, E. A.; Yakovlev, D. R.; Bayer, M.

    2009-08-01

    We study the electron-spin dynamics in p -type GaAs doped with magnetic Mn acceptors by means of time-resolved pump-probe and photoluminescence techniques. Measurements in transverse magnetic fields show a long spin-relaxation time of 20 ns that can be uniquely related to electrons. Application of weak longitudinal magnetic fields above 100 mT extends the spin-relaxation times up to microseconds which is explained by suppression of the Bir-Aronov-Pikus spin relaxation for the electron on the Mn acceptor.

  13. Distance measurements across randomly distributed nitroxide probes from the temperature dependence of the electron spin phase memory time at 240 GHz

    Science.gov (United States)

    Edwards, Devin T.; Takahashi, Susumu; Sherwin, Mark S.; Han, Songi

    2012-10-01

    At 8.5 T, the polarization of an ensemble of electron spins is essentially 100% at 2 K, and decreases to 30% at 20 K. The strong temperature dependence of the electron spin polarization between 2 and 20 K leads to the phenomenon of spin bath quenching: temporal fluctuations of the dipolar magnetic fields associated with the energy-conserving spin "flip-flop" process are quenched as the temperature of the spin bath is lowered to the point of nearly complete spin polarization. This work uses pulsed electron paramagnetic resonance (EPR) at 240 GHz to investigate the effects of spin bath quenching on the phase memory times (TM) of randomly-distributed ensembles of nitroxide molecules below 20 K at 8.5 T. For a given electron spin concentration, a characteristic, dipolar flip-flop rate (W) is extracted by fitting the temperature dependence of TM to a simple model of decoherence driven by the spin flip-flop process. In frozen solutions of 4-Amino-TEMPO, a stable nitroxide radical in a deuterated water-glass, a calibration is used to quantify average spin-spin distances as large as r¯=6.6 nm from the dipolar flip-flop rate. For longer distances, nuclear spin fluctuations, which are not frozen out, begin to dominate over the electron spin flip-flop processes, placing an effective ceiling on this method for nitroxide molecules. For a bulk solution with a three-dimensional distribution of nitroxide molecules at concentration n, we find W∝n∝1/r, which is consistent with magnetic dipolar spin interactions. Alternatively, we observe W∝n for nitroxides tethered to a quasi two-dimensional surface of large (Ø ˜ 200 nm), unilamellar, lipid vesicles, demonstrating that the quantification of spin bath quenching can also be used to discern the geometry of molecular assembly or organization.

  14. Possible Roles of Neural Electron Spin Networks in Memory and Consciousness

    CERN Document Server

    Hu, H P

    2004-01-01

    Spin is the origin of quantum effects in both Bohm and Hestenes quantum formulism and a fundamental quantum process associated with the structure of space-time. Thus, we have recently theorized that spin is the mind-pixel and developed a qualitative model of consciousness based on nuclear spins inside neural membranes and proteins. In this paper, we explore the possibility of unpaired electron spins being the mind-pixels. Besides free O2 and NO, the main sources of unpaired electron spins in neural membranes and proteins are transition metal ions and O2 and NO bound/absorbed to large molecules, free radicals produced through biochemical reactions and excited molecular triplet states induced by fluctuating internal magnetic fields. We show that unpaired electron spin networks inside neural membranes and proteins are modulated by action potentials through exchange and dipolar coupling tensors and spin-orbital coupling and g-factor tensors and perturbed by microscopically strong and fluctuating internal magnetic...

  15. Electron spin dynamics and optical orientation of Mn2+ ions in GaAs

    Science.gov (United States)

    Akimov, I. A.; Dzhioev, R. I.; Korenev, V. L.; Kusrayev, Yu. G.; Sapega, V. F.; Yakovlev, D. R.; Bayer, M.

    2013-04-01

    We present an overview of spin-related phenomena in GaAs doped with low concentration of Mn-acceptors (below 1018 cm-3). We use the combination of different experimental techniques such as spin-flip Raman scattering and time-resolved photoluminescence. This allows to evaluate the time evolution of both electron and Mn spins. We show that optical orientation of Mn ions is possible under application of weak magnetic field, which is required to suppress the manganese spin relaxation. The optically oriented Mn2+ ions maintain the spin and return part of the polarization back to the electron spin system providing a long-lived electron spin memory. This leads to a bunch of spectacular effects such as non-exponential electron spin decay and spin precession in the effective exchange fields.

  16. Resonance studies of H atoms adsorbed on frozen H2 surfaces

    International Nuclear Information System (INIS)

    Crampton, S.B.

    1980-01-01

    Observations are reported of the ground state hyperfine resonance of hydrogen atoms stored in a 5 cm. diameter bottle coated with frozen molecular hydrogen. Dephasing of the hyperfine resonance while the atoms are adsorbed produces frequency shifts which vary by a factor of two over the temperature range 3.7 K to 4.6 K and radiative decay rates which vary by a factor of five over this range. The magnitudes and temperature dependences of the frequency shifts and decay rates are consistent with a non-uniform distribution of surface adsorption energies with mean about 38(8) K, in agreement with theoretical estimates for a smooth surface. Extrapolation of the 30 nanosec. mean adsorption times at 4.2 K predicts very long adsorption times for H on H 2 below 1 K. Studies of level population recovery rates provide evidence for surface electron spin exchange collisions between adsorbed atoms with collision duration long compared to the hyperfine period, suggesting that the atoms are partially mobile on the surface. The lowest rates observed for level population recovery set a lower limit of about 500 atom-surface collisions at 4.2 K without recombination

  17. Quantum computation in semiconductor quantum dots of electron-spin asymmetric anisotropic exchange

    International Nuclear Information System (INIS)

    Hao Xiang; Zhu Shiqun

    2007-01-01

    The universal quantum computation is obtained when there exists asymmetric anisotropic exchange between electron spins in coupled semiconductor quantum dots. The asymmetric Heisenberg model can be transformed into the isotropic model through the control of two local unitary rotations for the realization of essential quantum gates. The rotations on each qubit are symmetrical and depend on the strength and orientation of asymmetric exchange. The implementation of the axially symmetric local magnetic fields can assist the construction of quantum logic gates in anisotropic coupled quantum dots. This proposal can efficiently use each physical electron spin as a logical qubit in the universal quantum computation

  18. Repetitive readout of a single electronic spin via quantum logic with nuclear spin ancillae.

    Science.gov (United States)

    Jiang, L; Hodges, J S; Maze, J R; Maurer, P; Taylor, J M; Cory, D G; Hemmer, P R; Walsworth, R L; Yacoby, A; Zibrov, A S; Lukin, M D

    2009-10-09

    Robust measurement of single quantum bits plays a key role in the realization of quantum computation and communication as well as in quantum metrology and sensing. We have implemented a method for the improved readout of single electronic spin qubits in solid-state systems. The method makes use of quantum logic operations on a system consisting of a single electronic spin and several proximal nuclear spin ancillae in order to repetitively readout the state of the electronic spin. Using coherent manipulation of a single nitrogen vacancy center in room-temperature diamond, full quantum control of an electronic-nuclear system consisting of up to three spins was achieved. We took advantage of a single nuclear-spin memory in order to obtain a 10-fold enhancement in the signal amplitude of the electronic spin readout. We also present a two-level, concatenated procedure to improve the readout by use of a pair of nuclear spin ancillae, an important step toward the realization of robust quantum information processors using electronic- and nuclear-spin qubits. Our technique can be used to improve the sensitivity and speed of spin-based nanoscale diamond magnetometers.

  19. The Stern-Gerlach experiment, electron spin and intermediate quantum mechanics

    International Nuclear Information System (INIS)

    Mackintosh, A.R.

    1983-01-01

    The paper deals with the theory of electron spin. The Stern-Gerlach experiment, the anticommutation relations and the properties of spin operators are discussed. The Pauli theory, Dirac transformation theory, the double Stern-Gerlach experiment, the EPR paradox and Bell's inequality are also covered. (U.K.)

  20. The HERA polarimeter and the first observation of electron spin polarization at HERA

    International Nuclear Information System (INIS)

    Barber, D.P.; Bremer, H.D.; Boege, M.; Brinkmann, R.; Gianfelice-Wendt, E.; Kaiser, H.; Klanner, R.; Lewin, H.C.; Meyners, N.; Vogel, W.; Brueckner, W.; Buescher, C.; Dueren, M.; Gaul, H.G.; Muecklich, A.; Neunreither, F.; Rith, K.; Scholz, C.; Steffens, E.; Veltri, M.; Wander, W.; Zapfe, K.; Zetsche, F.; Chapman, M.; Milner, R.; Coulter, K.; Delheij, P.P.J.; Haeusser, O.; Henderson, R.; Levy, P.; Vetterli, M.; Gressmann, H.; Janke, T.; Micheel, B.; Westphal, D.; Kaiser, R.; Losev, L.; Nowak, W.D.

    1992-10-01

    Electron spin polarizations of about 8% were observed at HERA in November 1991. In runs during 1992 utilizing special orbit corrections, polarization values close to 60% have been achieved. In this paper the polarimeter, the machine conditions, the data analysis, the first results and plans for future measurements are described. (orig.)

  1. Landau-Zener-Stückelberg Interferometry of a Single Electronic Spin in a Noisy Environment

    Directory of Open Access Journals (Sweden)

    Pu Huang

    2011-08-01

    Full Text Available We demonstrate quantum coherent control of single electronic spins in a nitron-vacancy center in diamond by exploiting and implementing the general concept of Landau-Zener-Stückelberg interferometry at room temperature. The interferometry manipulates an effective two-level system of electronic spins which are coupled to the nearby ^{14}N nuclear spin in the nitron-vacancy center as well as the nuclear spin bath in the diamond. With a microwave field to control the energy gap between the two levels and an AC field as the time-dependent driving field in Landau-Zener-Stückelberg interferometry, the interference pattern can be generated and controlled by controlling a number of parameters in the fields, corresponding to coherent control of the state of the electronic spins. In particular, the interference pattern is observed oscillating as a function of the frequency of the microwave field. Decays in the visibility of the interference pattern are also observed and well explained by numerical simulation which takes into account the thermal fluctuations arising from the nuclear bath. Therefore, our work also demonstrates that Landau-Zener-Stückelberg interferometry can be used for probing decoherence processes of electronic spins.

  2. Effect of Rashba and Dresselhaus Spin-Orbit Couplings on Electron Spin Polarization in a Hybrid Magnetic-Electric Barrier Nanostructure

    Science.gov (United States)

    Yang, Shi-Peng; Lu, Mao-Wang; Huang, Xin-Hong; Tang, Qiang; Zhou, Yong-Long

    2017-04-01

    A theoretical study has been carried out on the spin-dependent electron transport in a hybrid magnetic-electric barrier nanostructure with both Rashba and Dresselhaus spin-orbit couplings, which can be experimentally realized by depositing a ferromagnetic strip and a Schottky metal strip on top of a semiconductor heterostructure. The spin-orbit coupling-dependent transmission coefficient, conductance, and spin polarization are calculated by solving the Schrödinger equation exactly with the help of the transfer-matrix method. We find that both the magnitude and sign of the electron spin polarization vary strongly with the spin-orbit coupling strength. Thus, the degree of electron spin polarization can be manipulated by properly adjusting the spin-orbit coupling strength, and such a nanosystem can be employed as a controllable spin filter for spintronics applications.

  3. Alpha resonant scattering for astrophysical reaction studies

    Energy Technology Data Exchange (ETDEWEB)

    Yamaguchi, H.; Kahl, D.; Nakao, T. [Center for Nuclear Study (CNS), University of Tokyo, RIKEN campus, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Wakabayashi, Y.; Kubano, S. [The Institute of Physical and Chemical Research (RIKEN), 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Hashimoto, T. [Research Center for Nuclear Physics (RCNP), Osaka University, 10-1 Mihogaoka, Ibaraki, Osaka 567-0047 (Japan); Hayakawa, S. [Istituto Nazionale Fisica Nucleare - Laboratori Nazionali del Sud (INFN-LNS), Via S. Sofia 62, 95125 Catania (Italy); Kawabata, T. [Department of Physics, Kyoto University, Kita-Shirakawa, Kyoto 606-8502 (Japan); Iwasa, N. [Department of Physics, Tohoku University, Aoba, Sendai, Miyagi 980-8578 (Japan); Teranishi, T. [Department of Physics, Kyushu University, 6-10-1 Hakozaki, Fukuoka 812-8581 (Japan); Kwon, Y. K. [Institute for Basic Science, 70, Yuseong-daero 1689-gil, Yuseong-gu, Daejeon 305-811 (Korea, Republic of); Binh, D. N. [30 MeV Cyclotron Center, Tran Hung Dao Hospital, Hoan Kiem District, Hanoi (Viet Nam); Khiem, L. H.; Duy, N. G. [Institute of Physics, Vietnam Academy of Science and Technology, 18 Hong Quoc Viet, Nghia do, Hanoi (Viet Nam)

    2014-05-02

    Several alpha-induced astrophysical reactions have been studied at CRIB (CNS Radioactive Ion Beam separator), which is a low-energy RI beam separator at Center for Nuclear Study (CNS) of the University of Tokyo. One of the methods to study them is the α resonant scattering using the thick-target method in inverse kinematics. Among the recent studies at CRIB, the measurement of {sup 7}Be+α resonant scattering is discussed. Based on the result of the experiment, we evaluated the contributions of high-lying resonances for the {sup 7}Be(α,γ) reaction, and proposed a new cluster band in {sup 11}C.

  4. Alpha resonant scattering for astrophysical reaction studies

    International Nuclear Information System (INIS)

    Yamaguchi, H.; Kahl, D.; Nakao, T.; Wakabayashi, Y.; Kubano, S.; Hashimoto, T.; Hayakawa, S.; Kawabata, T.; Iwasa, N.; Teranishi, T.; Kwon, Y. K.; Binh, D. N.; Khiem, L. H.; Duy, N. G.

    2014-01-01

    Several alpha-induced astrophysical reactions have been studied at CRIB (CNS Radioactive Ion Beam separator), which is a low-energy RI beam separator at Center for Nuclear Study (CNS) of the University of Tokyo. One of the methods to study them is the α resonant scattering using the thick-target method in inverse kinematics. Among the recent studies at CRIB, the measurement of 7 Be+α resonant scattering is discussed. Based on the result of the experiment, we evaluated the contributions of high-lying resonances for the 7 Be(α,γ) reaction, and proposed a new cluster band in 11 C

  5. Radiolysis studies on reactive intermediates. Final report, February 1, 1970-August 31, 1980

    International Nuclear Information System (INIS)

    Kevan, L.

    1980-08-01

    Research highlights are briefly reviewed concerning studies of excess and solvated electrons, development of new electron spin resonance methods for maximizing the geometrical information about the surroundings of paramagnetic species in disordered systems, atom and ion solvation, and studies on other reactive intermediates. Titles of 155 research publications and 182 scientific talks presented on these areas are given

  6. Picture change error in quasirelativistic electron/spin density, Laplacian and bond critical points

    KAUST Repository

    Bučinský , Luká š; Kucková , Lenka; Malček, Michal; Koží šek, Jozef; Biskupič, Stanislav; Jayatilaka, Dylan; Bü chel, Gabriel E.; Arion, Vladimir B.

    2014-01-01

    The change of picture of the quasirelativistic Hartree-Fock wave functions is considered for electron/spin densities, the negative Laplacian of electron density and the appropriate bond critical point characteristics from the Quantum Theory of Atoms In Molecules (QTAIM). [OsCl5(Hpz)]- and [RuCl5(NO)]2- transition metal complexes are considered. Both, scalar relativistic and spin-orbit effects have been accounted for using the Infinite Order Two Component (IOTC) Hamiltonian. Picture change error (PCE) correction in the electron and spin densities and the Laplacian of electron density are treated analytically. Generally, PCE is found significant only in the core region of the atoms for the electron/spin density as well as Laplacian.©2014 Elsevier B.V. All rights reserved.

  7. Electron spin control and spin-libration coupling of a levitated nanodiamond

    Science.gov (United States)

    Hoang, Thai; Ma, Yue; Ahn, Jonghoon; Bang, Jaehoon; Robicheaux, Francis; Gong, Ming; Yin, Zhang-Qi; Li, Tongcang

    2017-04-01

    Hybrid spin-mechanical systems have great potentials in sensing, macroscopic quantum mechanics, and quantum information science. Recently, we optically levitated a nanodiamond and demonstrated electron spin control of its built-in nitrogen-vacancy (NV) centers in vacuum. We also observed the libration (torsional vibration) of a nanodiamond trapped by a linearly polarized laser beam in vacuum. We propose to achieve strong coupling between the electron spin of a NV center and the libration of a levitated nanodiamond with a uniform magnetic field. With a uniform magnetic field, multiple spins can couple to the torsional vibration at the same time. We propose to use this strong coupling to realize the Lipkin-Meshkov-Glick (LMG) model and generate rotational superposition states. This work is supported by the National Science Foundation under Grant No. 1555035-PHY.

  8. Picture change error in quasirelativistic electron/spin density, Laplacian and bond critical points

    KAUST Repository

    Bučinský, Lukáš

    2014-06-01

    The change of picture of the quasirelativistic Hartree-Fock wave functions is considered for electron/spin densities, the negative Laplacian of electron density and the appropriate bond critical point characteristics from the Quantum Theory of Atoms In Molecules (QTAIM). [OsCl5(Hpz)]- and [RuCl5(NO)]2- transition metal complexes are considered. Both, scalar relativistic and spin-orbit effects have been accounted for using the Infinite Order Two Component (IOTC) Hamiltonian. Picture change error (PCE) correction in the electron and spin densities and the Laplacian of electron density are treated analytically. Generally, PCE is found significant only in the core region of the atoms for the electron/spin density as well as Laplacian.©2014 Elsevier B.V. All rights reserved.

  9. Gradient ascent pulse engineering approach to CNOT gates in donor electron spin quantum computing

    International Nuclear Information System (INIS)

    Tsai, D.-B.; Goan, H.-S.

    2008-01-01

    In this paper, we demonstrate how gradient ascent pulse engineering (GRAPE) optimal control methods can be implemented on donor electron spin qubits in semiconductors with an architecture complementary to the original Kane's proposal. We focus on the high fidelity controlled-NOT (CNOT) gate and we explicitly find the digitized control sequences for a controlled-NOT gate by optimizing its fidelity using the effective, reduced donor electron spin Hamiltonian with external controls over the hyperfine A and exchange J interactions. We then simulate the CNOT-gate sequence with the full spin Hamiltonian and find that it has an error of 10 -6 that is below the error threshold of 10 -4 required for fault-tolerant quantum computation. Also the CNOT gate operation time of 100 ns is 3 times faster than 297 ns of the proposed global control scheme.

  10. Electron spin resonance studies on the detectability of radiation damage and radiosensitization of neoplastic cells. Coordinated programme on improvement of radiotherapy of cancer using modifiers of radiosensitivity of cells

    International Nuclear Information System (INIS)

    Lukiewicz, S.

    1982-01-01

    The comparison of direct and indirect ESR methods applicable for the examination of radiation damage to melanoma cells leads to the conclusion that only the indirect ones appear to be useful for its detection. The new results of animal experiments and clinical trials carried out according to the rules of radio-chelation therapy are briefly discussed. Selective incorporation of 35 S-labelled compounds by pigmented hamster melanoma cells was found to be followed by a depression of their proliferative activity in vitro and in situ, which may suggest the possible therapeutic value of endo-irradiation. The ESR measurements performed with the use of newly elaborated indirect methods revealed that pigmented and non-pigmented cells consume oxygen at significantly different rates, which means that oxygen utilization may contribute to the overall level of radioresistance of melanoma cells. This assumption has been confirmed by comparing the radiosensitivity of melanotic and amelanotic cells to fast neutrons. Pigment-containing hamster melanoma cells which are twice as resistant to low LET radiation as their non-pigmented counterparts, proved to be equally susceptible to neutrons. The chance of improving the efficiency of radiotherapy of malignant melanomas does not appear unlikely in the light of new experimental data and clinical trials

  11. Entanglement purification and concentration of electron-spin entangled states using quantum-dot spins in optical microcavities

    International Nuclear Information System (INIS)

    Wang Chuan; Zhang Yong; Jin Guangsheng

    2011-01-01

    We present an entanglement purification protocol and an entanglement concentration protocol for electron-spin entangled states, resorting to quantum-dot spin and optical-microcavity-coupled systems. The parity-check gates (PCGs) constructed by the cavity-spin-coupling system provide a different method for the entanglement purification of electron-spin entangled states. This protocol can efficiently purify an electron ensemble in a mixed entangled state. The PCGs can also concentrate electron-spin pairs in less-entangled pure states efficiently. The proposed methods are more flexible as only single-photon detection and single-electron detection are needed.

  12. Spin squeezing of atomic ensembles via nuclear-electronic spin entanglement

    DEFF Research Database (Denmark)

    Fernholz, Thomas; Krauter, Hanna; Jensen, Kasper

    2008-01-01

    quantum limit for quantum memory experiments and applications in quantum metrology and is thus a complementary alternative to spin squeezing obtained via inter-atom entanglement. Squeezing of the collective spin is verified by quantum state tomography.......We demonstrate spin squeezing in a room temperature ensemble of 1012 Cesium atoms using their internal structure, where the necessary entanglement is created between nuclear and electronic spins of each individual atom. This state provides improvement in measurement sensitivity beyond the standard...

  13. Optical manipulation of electron spin in quantum dot systems

    Science.gov (United States)

    Villas-Boas, Jose; Ulloa, Sergio; Govorov, Alexander

    2006-03-01

    Self-assembled quantum dots (QDs) are of particular interest for fundamental physics because of their similarity with atoms. Coupling two of such dots and addressing them with polarized laser light pulses is perhaps even more interesting. In this paper we use a multi-exciton density matrix formalism to model the spin dynamics of a system with single or double layers of QDs. Our model includes the anisotropic electron-hole exchange in the dots, the presence of wetting layer states, and interdot tunneling [1]. Our results show that it is possible to switch the spin polarization of a single self-assembled quantum dot under elliptically polarized light by increasing the laser intensity. In the nonlinear mechanism described here, intense elliptically polarized light creates an effective exchange channel between the exciton spin states through biexciton states, as we demonstrate by numerical and analytical methods. We further show that the effect persists in realistic ensembles of dots, and we propose alternative ways to detect it. We also extend our study to a double layer of quantum dots, where we find a competition between Rabi frequency and tunneling oscillations. [1] J. M. Villas-Boas, S. E. Ulloa, and A. O. Govorov, Phys. Rev. Lett. 94, 057404 (2005); Phys. Rev. B 69, 125342 (2004).

  14. Radiation damage in solid 5-halouracils. Electron spin resonance of single crystals of 5-bromouracil

    International Nuclear Information System (INIS)

    Oloff, H.; Huettermann, J.; Symons, M.C.R.

    1978-01-01

    Knowledge gained about halogen hyperfine interaction in radiation-induced free radicals formed at 300 K in a variety of 5-halouracil bases, together with the availability of crystal structure of 5-bromouracil aids in determination of the dominant radical structure. Details of its spectral parameters are presented, ESR spectra of single crystals of 5-bromouracil irradiated at 300K induce the presence of free radicals which indicate the loss of hydrogen from N 1 , confirming structure I as the dominant radical. The powder spectrum of 5-bromouracil measured after irradiation at 300K shows x features of radical I, but they appear superimposed by lines of another radical also involving bromine hyperfine interaction. These lines most probably belong to the hydrogen-addition radical II

  15. Detection of electron beam irradiated crude drugs by electron spin resonance (ESR)

    International Nuclear Information System (INIS)

    Yamaoki, Rumi; Kimura, Shojiro; Aoki, Kenji; Nishimoto, Susumu

    2007-01-01

    Perillae Herba, Sennae Folium, Cinnamomi Cortex, Phellodendri Cortex, Ginseng Radix, Glycyrrhizae Radix, Paeoniae Radix, and Zingiberis Rhizoma were irradiated with electron beam (5 MeV) and organic radicals were detected by ESR measurement, before and after irradiation (10 kGy). A single line spectrum was detected at around g=2.005 in non-irradiated crude drugs, and radical concentrations were high in the leaf varieties of crude drugs. After irradiation, the signal intensity around g=2.005 increased, and a new subsignal was detected as a 3 mT shoulder of this signal. Broad, asymmetrically divided signals were also detected in irradiated root varieties of crude drugs. The free radical localized on the organic components of irradiated crude drugs tended to decrease with the water content. After irradiation, signal intensity reduced and reached a steady state after about 1 to 2 months. However, specificity of the ESR signal shape appearing after irradiation continued to be detectable for 6 months in leaf varieties and for a year in bark and root varieties of crude drugs. Consequently, it was concluded that ESR could be applied as an initial screening procedure to detect irradiated crude drugs. (author)

  16. Electron spin resonance spectroscopy on packing material: An indirect identification of radiation treatment

    International Nuclear Information System (INIS)

    Helle, N.; Zachaeus, U.; Ehlers, D.; Schreiber, G.A.

    1993-01-01

    In those cases, where foodstuffs did not contain hard and dry parts, e.s.r. spectroscopy can be helpful as a fast and reliable screening method measuring the package material instead of the (liquid) content. Not only natural cellulose materials like paper can be used but also some commercially used synthetic polymeres are suited. Especially polypropylene and some polystyrene packagings produced stable radicals upon irradiation. Polyethylene can only give informations about a previous irradiation of the product if it was stored at deep temperatures. At room temperature the radical concentration decreases very fast and radicals could only be detected for a short time. (orig.)

  17. Electron spin resonance (ESR) spectroscopy applied to radiation dosimetry and other fields

    International Nuclear Information System (INIS)

    Schneider, C.C.J.

    1994-12-01

    A short introduction to the theory and practice of ESR spectroscopy is given. ESR alanine dosimetry for low and high LET (linear energy transfer) ionising radiation is described, indicating its advantages over traditional methods. Problems arising in the therapy dose range (below 5 Gy), and possible future developments, are mentioned. The application of ESR to the radiation processing of materials and foodstuffs, to geological dating, biology, molecular chemistry and to medicine is discussed. Some examples of chemical analyses are also presented. (orig.)

  18. Detection of prior irradiation in dried fruits by electron spin resonance (ESR)

    International Nuclear Information System (INIS)

    Esteves, M.P.; Andrade, M.E.; Empis, J.

    1998-01-01

    Complete text of publication follows. Dried almonds, raisins, dates and pistachio were irradiated using gamma radiation and electron beam with an average absorbed dose of 5 kGy. The radiation treatment was detected by ESR spectroscopy. Different parts of the dried fruits were analysed as follows: almonds: skin; raisins: dried pulp (at 30 deg C for one week); dates: dried pulp (at 30 deg C for one week) and stone; pistachio: nutshell. A Bruker ECS 106 EPR Spectrometer, at a microwave power of 0.4 mW, at room temperature was used. The analysis were carried out 2-3 months and 6 months after irradiation. A series of signals, tentatively described as 'cellulose-like', 'sugar-like' and 'complex' were observed, and some slight differences between spectra recorded from samples irradiated with gamma and electrons were evident

  19. Isotope enrichment by electron spin resonance transitions of the intermediate radical pair

    International Nuclear Information System (INIS)

    Okazaki, M.; Shiga, T.; Sakata, S.; Konaka, R.; Toriyama, K.

    1988-01-01

    Microwave effects on the spin adduct yield were observed in the photoreduction of menadione in micellar solutions with ordinary sodium dodecyl sulfate (SDS), deuterium-labeled SDS, and a mixture of them. A large isotope effect was found in the microwave modulation of the spin adduct yield, which is due to the ESR transitions of the transient radical pair in the reaction. It is demonstrated for the first time that the microwave field can be used to enrich one of the isotopes which coexist in the system

  20. Detection of prior irradiation in dried fruits by electron spin resonance (ESR)

    Energy Technology Data Exchange (ETDEWEB)

    Esteves, M P [Instituto Nacional de Investigacao Agraria (EAN), Oeiras (Portugal); Andrade, M E [Instituto Tecnologico e Nuclear (ITN), Sacavem (Portugal); Empis, J [Instituto Superior Tecnico (IST), Lisboa (Portugal)

    1999-12-31

    Complete text of publication follows. Dried almonds, raisins, dates and pistachio were irradiated using gamma radiation and electron beam with an average absorbed dose of 5 kGy. The radiation treatment was detected by ESR spectroscopy. Different parts of the dried fruits were analysed as follows: almonds: skin; raisins: dried pulp (at 30 deg C for one week); dates: dried pulp (at 30 deg C for one week) and stone; pistachio: nutshell. A Bruker ECS 106 EPR Spectrometer, at a microwave power of 0.4 mW, at room temperature was used. The analysis were carried out 2-3 months and 6 months after irradiation. A series of signals, tentatively described as `cellulose-like`, `sugar-like` and `complex` were observed, and some slight differences between spectra recorded from samples irradiated with gamma and electrons were evident.

  1. Electron spin resonance spectroscopy of organic radicals spectroscopy of organic radicals

    CERN Document Server

    Gerson, Fabian

    2006-01-01

    ""This book should serve as a comprehensive one-volume source for finding what is known about the splitting constants and g factors of virtually all types of organic radicals."" Journal of the American Chemistry Society, 2004, Vol. 126 No. 20

  2. Electron spin resonance of spin-trapped radicals of amines and polyamines

    International Nuclear Information System (INIS)

    Mossoba, M.M.; Rosenthal, Ionel; Riesz, Peter

    1982-01-01

    The reactions of hydroxyl radicals with methylamine, dimethylamine, trimethylamine, diethylamine, sec-butylamine, ethylene-diamine, 1,3-diaminopropane, putrescine, cadaverine, 1,7-diaminoheptane, ornithine, spermidine, spermine, agmatine, and arcaine in aqueous solutions have been investigated by spin-trapping and esr. Hydroxyl radicals were generated by the uv photolysis of H 2 O 2 and 2-methyl-2-nitrosopropane (MNP) was used as the spin-trap. The effects of ionizing radiation on the same polyamines in the polycrystalline state were also investigated. The free radicals produced by ν-radiolysis of these solids at room temperature in the absence of air were identified by dissolution in aqueous solutions of MNP. The predominant reaction of OH radicals with amines and polyamines below pH 7 was the abstraction of hydrogen atoms from a carbon that is not adjacent to the protonated amino group. For agmatine and arcaine which contain guanidinium groups abstraction occurred from the α-CH. Dimethylamine was oxidized to the dimethylnitroxyl radical by H 2 O 2 in the dark. ν-Radiolysis of polyamines in the polycrystalline state generated radicals due to H-abstraction from either the α-Ch or from a carbon atom in the middle of the alkyl chain. The deamination radical was obtained from ornithine

  3. The strong influence of the solvent on the electron spin resonance spectra of semiquinone radical anions

    DEFF Research Database (Denmark)

    Spanget-Larsen, Jens

    2013-01-01

    ). The proton hyperfine constants predicted for the chrysazin semiquinone radical anion were highly sensitive to the assumed dielectric constant ε of the solvent continuum, inverting the relative magnitudes of the hyperfine constants and thereby leading to agreement with the observed data published by Stegmann...

  4. Dust grain resonant capture: A statistical study

    Science.gov (United States)

    Marzari, F.; Vanzani, V.; Weidenschilling, S. J.

    1993-01-01

    A statistical approach, based on a large number of simultaneous numerical integrations, is adopted to study the capture in external mean motion resonances with the Earth of micron size dust grains perturbed by solar radiation and wind forces. We explore the dependence of the resonant capture phenomenon on the initial eccentricity e(sub 0) and perihelion argument w(sub 0) of the dust particle orbit. The intensity of both the resonant and dissipative (Poynting-Robertson and wind drag) perturbations strongly depends on the eccentricity of the particle while the perihelion argument determines, for low inclination, the mutual geometrical configuration of the particle's orbit with respect to the Earth's orbit. We present results for three j:j+1 commensurabilities (2:3, 4:5 and 6:7) and also for particle sizes s = 15, 30 microns. This study extends our previous work on the long term orbital evolution of single dust particles trapped into resonances with the Earth.

  5. SS-HORSE method for studying resonances

    Energy Technology Data Exchange (ETDEWEB)

    Blokhintsev, L. D. [Moscow State University, Skobeltsyn Institute of Nuclear Physics (Russian Federation); Mazur, A. I.; Mazur, I. A., E-mail: 008043@pnu.edu.ru [Pacific National University (Russian Federation); Savin, D. A.; Shirokov, A. M. [Moscow State University, Skobeltsyn Institute of Nuclear Physics (Russian Federation)

    2017-03-15

    A new method for analyzing resonance states based on the Harmonic-Oscillator Representation of Scattering Equations (HORSE) formalism and analytic properties of partial-wave scattering amplitudes is proposed. The method is tested by applying it to the model problem of neutral-particle scattering and can be used to study resonance states on the basis of microscopic calculations performed within various versions of the shell model.

  6. Suppression of Raman electron spin relaxation of radicals in crystals. Comparison of Cu2+ and free radical relaxation in triglycine sulfate and Tutton salt single crystals.

    Science.gov (United States)

    Hoffmann, S K; Goslar, J; Lijewski, S

    2011-08-31

    Electron spin-lattice relaxation was measured by the electron spin echo method in a broad temperature range above 4.2 K for Cu(2+) ions and free radicals produced by ionizing radiation in triglycine sulfate (TGS) and Tutton salt (NH4)(2)Zn(SO4)2 ⋅ 6H2O crystals. Localization of the paramagnetic centres in the crystal unit cells was determined from continuous wave electron paramagnetic resonance spectra. Various spin relaxation processes and mechanisms are outlined. Cu(2+) ions relax fast via two-phonon Raman processes in both crystals involving the whole phonon spectrum of the host lattice. This relaxation is slightly slower for TGS where Cu(2+) ions are in the interstitial position. The ordinary Raman processes do not contribute to the radical relaxation which relaxes via the local phonon mode. The local mode lies within the acoustic phonon band for radicals in TGS but within the optical phonon range in (NH4)(2)Zn(SO4)2 ⋅ 6H2O. In the latter the cross-relaxation was considered. A lack of phonons around the radical molecules suggested a local crystal amorphisation produced by x- or γ-rays.

  7. Structure of Rhodium in an Ultradispersed Rhodium/Alumina Catalyst as Studied by EXAFS and Other Technique

    NARCIS (Netherlands)

    Koningsberger, D.C.; Blik, H.F.J. van 't; Zon, J.B.A.D. van; Huizinga, T.; Vis, J.C.; Prins, R.

    1985-01-01

    The structure of rhodium in an ultradispersed 0.57 wt % Rh/y-Al,O, catalyst before and after CO adsorption was studied with extended X-ray absorption fine structure (EXAFS), X-ray photoelectron spectroscopy (XPS), electron spin resonance (ESR), temperature programmed reduction (TPR), CO infrared

  8. Strain-Induced Spin-Resonance Shifts in Silicon Devices

    Science.gov (United States)

    Pla, J. J.; Bienfait, A.; Pica, G.; Mansir, J.; Mohiyaddin, F. A.; Zeng, Z.; Niquet, Y. M.; Morello, A.; Schenkel, T.; Morton, J. J. L.; Bertet, P.

    2018-04-01

    In spin-based quantum-information-processing devices, the presence of control and detection circuitry can change the local environment of a spin by introducing strain and electric fields, altering its resonant frequencies. These resonance shifts can be large compared to intrinsic spin linewidths, and it is therefore important to study, understand, and model such effects in order to better predict device performance. We investigate a sample of bismuth donor spins implanted in a silicon chip, on top of which a superconducting aluminum microresonator is fabricated. The on-chip resonator provides two functions: it produces local strain in the silicon due to the larger thermal contraction of the aluminum, and it enables sensitive electron spin-resonance spectroscopy of donors close to the surface that experience this strain. Through finite-element strain simulations, we are able to reconstruct key features of our experiments, including the electron spin-resonance spectra. Our results are consistent with a recently observed mechanism for producing shifts of the hyperfine interaction for donors in silicon, which is linear with the hydrostatic component of an applied strain.

  9. Asymmetric recombination and electron spin relaxation in the semiclassical theory of radical pair reactions

    International Nuclear Information System (INIS)

    Lewis, Alan M.; Manolopoulos, David E.; Hore, P. J.

    2014-01-01

    We describe how the semiclassical theory of radical pair recombination reactions recently introduced by two of us [D. E. Manolopoulos and P. J. Hore, J. Chem. Phys. 139, 124106 (2013)] can be generalised to allow for different singlet and triplet recombination rates. This is a non-trivial generalisation because when the recombination rates are different the recombination process is dynamically coupled to the coherent electron spin dynamics of the radical pair. Furthermore, because the recombination operator is a two-electron operator, it is no longer sufficient simply to consider the two electrons as classical vectors: one has to consider the complete set of 16 two-electron spin operators as independent classical variables. The resulting semiclassical theory is first validated by comparison with exact quantum mechanical results for a model radical pair containing 12 nuclear spins. It is then used to shed light on the spin dynamics of a carotenoid-porphyrin-fullerene triad containing considerably more nuclear spins which has recently been used to establish a “proof of principle” for the operation of a chemical compass [K. Maeda, K. B. Henbest, F. Cintolesi, I. Kuprov, C. T. Rodgers, P. A. Liddell, D. Gust, C. R. Timmel, and P. J. Hore, Nature (London) 453, 387 (2008)]. We find in particular that the intriguing biphasic behaviour that has been observed in the effect of an Earth-strength magnetic field on the time-dependent survival probability of the photo-excited C ·+ PF ·− radical pair arises from a delicate balance between its asymmetric recombination and the relaxation of the electron spin in the carotenoid radical

  10. Quantum teleportation and entanglement swapping of electron spins in superconducting hybrid structures

    Energy Technology Data Exchange (ETDEWEB)

    Bubanja, Vladimir, E-mail: vladimir.bubanja@callaghaninnovation.govt.nz

    2015-06-15

    We present schemes for quantum teleportation and entanglement swapping of electronic spin states in hybrid superconductor–normal-metal systems. The proposed schemes employ subgap transport whereby the lowest order processes involve Cooper pair-electron and double Cooper-pair cotunneling in quantum teleportation and entanglement swapping protocols, respectively. The competition between elastic cotunneling and Cooper-pair splitting results in the success probability of 25% in both cases. Described implementations of these protocols are within reach of present-day experimental techniques.

  11. Mode locking of electron spin coherences in singly charged quantum dots.

    Science.gov (United States)

    Greilich, A; Yakovlev, D R; Shabaev, A; Efros, Al L; Yugova, I A; Oulton, R; Stavarache, V; Reuter, D; Wieck, A; Bayer, M

    2006-07-21

    The fast dephasing of electron spins in an ensemble of quantum dots is detrimental for applications in quantum information processing. We show here that dephasing can be overcome by using a periodic train of light pulses to synchronize the phases of the precessing spins, and we demonstrate this effect in an ensemble of singly charged (In,Ga)As/GaAs quantum dots. This mode locking leads to constructive interference of contributions to Faraday rotation and presents potential applications based on robust quantum coherence within an ensemble of dots.

  12. Electron spin interactions in chemistry and biology fundamentals, methods, reactions mechanisms, magnetic phenomena, structure investigation

    CERN Document Server

    Likhtenshtein, Gertz

    2016-01-01

    This book presents the versatile and pivotal role of electron spin interactions in nature. It provides the background, methodologies and tools for basic areas related to spin interactions, such as spin chemistry and biology, electron transfer, light energy conversion, photochemistry, radical reactions, magneto-chemistry and magneto-biology. The book also includes an overview of designing advanced magnetic materials, optical and spintronic devices and photo catalysts. This monograph appeals to scientists and graduate students working in the areas related to spin interactions physics, biophysics, chemistry and chemical engineering.

  13. A Resonant Damping Study Using Piezoelectric Materials

    Science.gov (United States)

    Min, J. B.; Duffy, K. P.; Choi, B. B.; Morrison, C. R.; Jansen, R. H.; Provenza, A. J.

    2008-01-01

    Excessive vibration of turbomachinery blades causes high cycle fatigue (HCF) problems requiring damping treatments to mitigate vibration levels. Based on the technical challenges and requirements learned from previous turbomachinery blade research, a feasibility study of resonant damping control using shunted piezoelectric patches with passive and active control techniques has been conducted on cantilever beam specimens. Test results for the passive damping circuit show that the optimum resistive shunt circuit reduces the third bending resonant vibration by almost 50%, and the optimum inductive circuit reduces the vibration by 90%. In a separate test, active control reduced vibration by approximately 98%.

  14. Magnetic resonance studies of solid polymers

    International Nuclear Information System (INIS)

    Lenk, R.

    1969-01-01

    This paper is a review of the application of nuclear magnetic resonance (NMR) to solid polymers. In the first, theoretical part, the elements of the theory of NMR, which are necessary for the study of the properties of solid polymers are discussed: the moments method, nuclear relaxation and the distribution of correlation times. In the second part the experimental results are presented. (author) [fr

  15. Quantum State Transfer from a Single Photon to a Distant Quantum-Dot Electron Spin

    Science.gov (United States)

    He, Yu; He, Yu-Ming; Wei, Yu-Jia; Jiang, Xiao; Chen, Kai; Lu, Chao-Yang; Pan, Jian-Wei; Schneider, Christian; Kamp, Martin; Höfling, Sven

    2017-08-01

    Quantum state transfer from flying photons to stationary matter qubits is an important element in the realization of quantum networks. Self-assembled semiconductor quantum dots provide a promising solid-state platform hosting both single photon and spin, with an inherent light-matter interface. Here, we develop a method to coherently and actively control the single-photon frequency bins in superposition using electro-optic modulators, and measure the spin-photon entanglement with a fidelity of 0.796 ±0.020 . Further, by Greenberger-Horne-Zeilinger-type state projection on the frequency, path, and polarization degrees of freedom of a single photon, we demonstrate quantum state transfer from a single photon to a single electron spin confined in an InGaAs quantum dot, separated by 5 m. The quantum state mapping from the photon's polarization to the electron's spin is demonstrated along three different axes on the Bloch sphere, with an average fidelity of 78.5%.

  16. Electron spin-echo envelope modulation (ESEEM) reveals water and phosphate interactions with the KcsA potassium channel.

    Science.gov (United States)

    Cieslak, John A; Focia, Pamela J; Gross, Adrian

    2010-02-23

    Electron spin-echo envelope modulation (ESEEM) spectroscopy is a well-established technique for the study of naturally occurring paramagnetic metal centers. The technique has been used to study copper complexes, hemes, enzyme mechanisms, micellar water content, and water permeation profiles in membranes, among other applications. In the present study, we combine ESEEM spectroscopy with site-directed spin labeling (SDSL) and X-ray crystallography in order to evaluate the technique's potential as a structural tool to describe the native environment of membrane proteins. Using the KcsA potassium channel as a model system, we demonstrate that deuterium ESEEM can detect water permeation along the lipid-exposed surface of the KcsA outer helix. We further demonstrate that (31)P ESEEM is able to identify channel residues that interact with the phosphate headgroup of the lipid bilayer. In combination with X-ray crystallography, the (31)P data may be used to define the phosphate interaction surface of the protein. The results presented here establish ESEEM as a highly informative technique for SDSL studies of membrane proteins.

  17. Universal quantum gates on electron-spin qubits with quantum dots inside single-side optical microcavities.

    Science.gov (United States)

    Wei, Hai-Rui; Deng, Fu-Guo

    2014-01-13

    We present some compact quantum circuits for a deterministic quantum computing on electron-spin qubits assisted by quantum dots inside single-side optical microcavities, including the CNOT, Toffoli, and Fredkin gates. They are constructed by exploiting the giant optical Faraday rotation induced by a single-electron spin in a quantum dot inside a single-side optical microcavity as a result of cavity quantum electrodynamics. Our universal quantum gates have some advantages. First, all the gates are accomplished with a success probability of 100% in principle. Second, our schemes require no additional electron-spin qubits and they are achieved by some input-output processes of a single photon. Third, our circuits for these gates are simple and economic. Moreover, our devices for these gates work in both the weak coupling and the strong coupling regimes, and they are feasible in experiment.

  18. Magnetic resonance imaging apparatus

    International Nuclear Information System (INIS)

    Ehnholm, G.J.

    1991-01-01

    This patent describes an electron spin resonance enhanced magnetic resonance (MR) imaging (ESREMRI) apparatus able to generate a primary magnetic field during periods of nuclear spin transition excitation and magnetic resonance signal detection. This allows the generation of ESREMRI images of a subject. A primary magnetic field of a second and higher value generated during periods of nuclear spin transition excitation and magnetic resonance signal detection can be used to generate conventional MR images of a subject. The ESREMRI and native MR images so generated may be combined, (or superimposed). (author)

  19. Electron spin-lattice relaxation of low-symmetry Ni.sup.2+./sup. centers in LiF

    Czech Academy of Sciences Publication Activity Database

    Azamat, Dmitry; Badalyan, A. G.; Dejneka, Alexandr; Jastrabík, Lubomír; Lančok, Ján

    2014-01-01

    Roč. 104, č. 25 (2014), "252902-1"-"252902-4" ISSN 0003-6951 R&D Projects: GA MŠk(CZ) LM2011029; GA TA ČR TA01010517; GA ČR GAP108/12/1941 Grant - others:SAFMAT(XE) CZ.2.16/3.1.00/22132 Institutional support: RVO:68378271 Keywords : Ni 2+ centers * LiF single crystals * electron spin-lattice relaxation * electron spin echo technique Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.302, year: 2014

  20. Magnetic resonance studies of intercalation compounds

    International Nuclear Information System (INIS)

    Miller, G.R.

    1990-01-01

    During the last three or four years, nearly tow hundred papers have been published that used NMR or ESR spectroscopy to study compounds formed by the intercalation of molecules or ions into the van der Waals gap of a layered hast compound. The host lattices have ranged from the simple, such as graphite, to the complex, such as clay. In many cases, magnetic resonance techniques now enable one to obtain quite detailed information on even fairly complex intercalated species, on the nature of the changes in the host lattice accompanying intercalation, and on the nature of the interactions between the intercalant species and the host lattice. Magnetic resonance is used in conunction with many other techniques to obtain a fuller picture of these interesting systems, but this review will limit its focus to the use of NMR and ESR techniques. (author). 51 refs

  1. Nanodiamond graphitization: a magnetic resonance study

    International Nuclear Information System (INIS)

    Panich, A M; Shames, A I; Sergeev, N A; Olszewski, M; McDonough, J K; Mochalin, V N; Gogotsi, Y

    2013-01-01

    We report on the first nuclear magnetic resonance (NMR) and electron paramagnetic resonance (EPR) study of the high-temperature nanodiamond-to-onion transformation. 1 H, 13 C NMR and EPR spectra of the initial nanodiamond samples and those annealed at 600, 700, 800 and 1800 ° C were measured. For the samples annealed at 600 to 800 ° C, our NMR data reveal the early stages of the surface modification, as well as a progressive increase in sp 2 carbon content with increased annealing temperature. Such quantitative experimental data were recorded for the first time. These findings correlate with EPR data on the sensitivity of the dangling bond EPR line width to air content, progressing with rising annealing temperature, that evidences consequent graphitization of the external layers of the diamond core. The sample annealed at 1800 ° C shows complete conversion of nanodiamond particles into carbon onions. (paper)

  2. Strain-induced phase transition and electron spin-polarization in graphene spirals.

    Science.gov (United States)

    Zhang, Xiaoming; Zhao, Mingwen

    2014-07-16

    Spin-polarized triangular graphene nanoflakes (t-GNFs) serve as ideal building blocks for the long-desired ferromagnetic graphene superlattices, but they are always assembled to planar structures which reduce its mechanical properties. Here, by joining t-GNFs in a spiral way, we propose one-dimensional graphene spirals (GSs) with superior mechanical properties and tunable electronic structures. We demonstrate theoretically the unique features of electron motion in the spiral lattice by means of first-principles calculations combined with a simple Hubbard model. Within a linear elastic deformation range, the GSs are nonmagnetic metals. When the axial tensile strain exceeds an ultimate strain, however, they convert to magnetic semiconductors with stable ferromagnetic ordering along the edges. Such strain-induced phase transition and tunable electron spin-polarization revealed in the GSs open a new avenue for spintronics devices.

  3. Neuromorphic computing enabled by physics of electron spins: Prospects and perspectives

    Science.gov (United States)

    Sengupta, Abhronil; Roy, Kaushik

    2018-03-01

    “Spintronics” refers to the understanding of the physics of electron spin-related phenomena. While most of the significant advancements in this field has been driven primarily by memory, recent research has demonstrated that various facets of the underlying physics of spin transport and manipulation can directly mimic the functionalities of the computational primitives in neuromorphic computation, i.e., the neurons and synapses. Given the potential of these spintronic devices to implement bio-mimetic computations at very low terminal voltages, several spin-device structures have been proposed as the core building blocks of neuromorphic circuits and systems to implement brain-inspired computing. Such an approach is expected to play a key role in circumventing the problems of ever-increasing power dissipation and hardware requirements for implementing neuro-inspired algorithms in conventional digital CMOS technology. Perspectives on spin-enabled neuromorphic computing, its status, and challenges and future prospects are outlined in this review article.

  4. Photo-Induced Electron Spin Polarization in a Narrow Band Gap Semiconductor Nanostructure

    International Nuclear Information System (INIS)

    Peter, A. John; Lee, Chang Woo

    2012-01-01

    Photo-induced spin dependent electron transmission through a narrow gap InSb/InGa x Sb 1−x semiconductor symmetric well is theoretically studied using transfer matrix formulism. The transparency of electron transmission is calculated as a function of electron energy for different concentrations of gallium. Enhanced spin-polarized photon assisted resonant tunnelling in the heterostructure due to Dresselhaus and Rashba spin-orbit coupling induced splitting of the resonant level and compressed spin-polarization are observed. Our results show that Dresselhaus spin-orbit coupling is dominant for the photon effect and the computed polarization efficiency increases with the photon effect and the gallium concentration

  5. Membrane metamaterial resonators with a sharp resonance: A comprehensive study towards practical terahertz filters and sensors

    Directory of Open Access Journals (Sweden)

    Yongyao Chen

    2012-06-01

    Full Text Available We investigate the resonant properties of high quality-factor membrane-based metamaterial resonators functioning in the terahertz regime. A number of factors, including the resonator geometry, dielectric loss, and most importantly the membrane thickness are found to extensively influence the resonance strength and quality factor of the sharp resonance. Further studies on the membrane thickness-dependent-sensitivity for sensing applications reveal that high quality-factor membrane metamaterials with a moderate thickness ranging from 10 to 50 μm are the most promising option towards developing realistic integrated terahertz filters and sensors.

  6. Magnetic resonance of phase transitions

    CERN Document Server

    Owens, Frank J; Farach, Horacio A

    1979-01-01

    Magnetic Resonance of Phase Transitions shows how the effects of phase transitions are manifested in the magnetic resonance data. The book discusses the basic concepts of structural phase and magnetic resonance; various types of magnetic resonances and their underlying principles; and the radiofrequency methods of nuclear magnetic resonance. The text also describes quadrupole methods; the microwave technique of electron spin resonance; and the Mössbauer effect. Phase transitions in various systems such as fluids, liquid crystals, and crystals, including paramagnets and ferroelectrics, are also

  7. Resonant Tunneling Spin Pump

    Science.gov (United States)

    Ting, David Z.

    2007-01-01

    The resonant tunneling spin pump is a proposed semiconductor device that would generate spin-polarized electron currents. The resonant tunneling spin pump would be a purely electrical device in the sense that it would not contain any magnetic material and would not rely on an applied magnetic field. Also, unlike prior sources of spin-polarized electron currents, the proposed device would not depend on a source of circularly polarized light. The proposed semiconductor electron-spin filters would exploit the Rashba effect, which can induce energy splitting in what would otherwise be degenerate quantum states, caused by a spin-orbit interaction in conjunction with a structural-inversion asymmetry in the presence of interfacial electric fields in a semiconductor heterostructure. The magnitude of the energy split is proportional to the electron wave number. Theoretical studies have suggested the possibility of devices in which electron energy states would be split by the Rashba effect and spin-polarized currents would be extracted by resonant quantum-mechanical tunneling.

  8. Magnetic resonance of semiconductors and their nanostructures basic and advanced applications

    CERN Document Server

    Baranov, Pavel G; Jelezko, Fedor; Wrachtrup, Jörg

    2017-01-01

    This book explains different magnetic resonance (MR) techniques and uses different combinations of these techniques to analyze defects in semiconductors and nanostructures. It also introduces novelties such as single defects MR and electron-paramagnetic-resonance-based methods: electron spin echo, electrically detected magnetic resonance, optically detected magnetic resonance and electron-nuclear double resonance – the designated tools for investigating the structural and spin properties of condensed systems, living matter, nanostructures and nanobiotechnology objects. Further, the authors address problems existing in semiconductor and nanotechnology sciences that can be resolved using MR, and discuss past, current and future applications of MR, with a focus on advances in MR methods. The book is intended for researchers in MR studies of semiconductors and nanostructures wanting a comprehensive review of what has been done in their own and related fields of study, as well as future perspectives.

  9. Magnetic resonance spectroscopy studies in migraine

    Energy Technology Data Exchange (ETDEWEB)

    Montagna, P.; Cortelli, P.; Barbiroli, B. (Inst. of Medical Pathology, Univ. of Bologna (Italy))

    1994-06-01

    The authors describe the method of [sup 31]phosphorus magnetic resonance spectroscopy and review the results when it is applied to the study of brain and muscle energy metabolism in migraine subjects. Brain energy metabolism appears to be abnormal in all major subtypes of migraine when measured both during and between attacks. Impaired energy metabolism is also documented in skeletal muscle. It is suggested that migraine is associated with a generalized disorder of mitochondrial oxidative phosphorylation and that this may constitute a threshold for the triggering of migraine attacks. 47 refs., 10 figs., 3 tabs.

  10. Advances in mechanical detection of magnetic resonance

    International Nuclear Information System (INIS)

    Kuehn, Seppe; Hickman, Steven A.; Marohn, John A.

    2008-01-01

    The invention and initial demonstration of magnetic resonance force microscopy (MRFM) in the early 1990s launched a renaissance of mechanical approaches to detecting magnetic resonance. This article reviews progress made in MRFM in the last decade, including the demonstration of scanned probe detection of magnetic resonance (electron spin resonance, ferromagnetic resonance, and nuclear magnetic resonance) and the mechanical detection of electron spin resonance from a single spin. Force and force-gradient approaches to mechanical detection are reviewed and recent related work using attonewton sensitivity cantilevers to probe minute fluctuating electric fields near surfaces is discussed. Given recent progress, pushing MRFM to single proton sensitivity remains an exciting possibility. We will survey some practical and fundamental issues that must be resolved to meet this challenge.

  11. [Gastric magnetic resonance study (methods, semiotics)].

    Science.gov (United States)

    Stashuk, G A

    2003-01-01

    The paper shows the potentialities of gastric study by magnetic resonance imaging (MRI). The methodic aspects of gastric study have been worked out. The MRI-semiotics of the unchanged and tumor-affected wall of the stomach and techniques in examining patients with gastric cancer of various sites are described. Using the developed procedure, MRI was performed in 199 patients, including 154 patients with gastric pathology and 45 control individuals who had no altered gastric wall. Great emphasis is placed on the role of MRI in the diagnosis of endophytic (diffuse) gastric cancer that is of priority value in its morphological structure. MRI was found to play a role in the diagnosis of the spread of a tumorous process both along the walls of the stomach and to its adjacent anatomic structures.

  12. A study of the magnetic resonance in a single-crystal Ni50.47Mn28.17Ga21.36 alloy

    International Nuclear Information System (INIS)

    Gavriljuk, V G; Dobrinsky, A; Shanina, B D; Kolesnik, S P

    2006-01-01

    The single-crystal non-stoichiometric magnetic shape memory alloy Ni 1-x-y Mn x Ga y with x = 0.2817, y = 0.2136 is studied using magnetic resonance spectroscopy: ferromagnetic resonance (FMR) and conduction electron spin resonance (CESR). The temperature dependence of the integral intensity, the resonance field and the line-width are measured across the wide temperature interval from 4.2 to 570 K. Three phase transformations are found in this alloy: paramagnetic ↔ ferromagnetic with a Curie temperature of 360 K, austenite-to-martensite (direct with T ms = 312 K and reverse with T as = 313 K), and a transformation at T = 45 K, suggestive of the spin-glass state. The angular dependence of the FMR signals is measured in the martensitic and austenitic states before and after the martensite-to-austenite transition. The experimental data are used for determination of the magnetization M m and anisotropy parameters K 1 and K 2 in the martensitic state. The obtained coefficient K 2 is determined to be not small and, moreover, it is comparable with K 1 . The temperature dependence of the resonance signals is also investigated at temperatures significantly higher than T C , where FMR was transformed to CESR. In the paramagnetic austenitic state (above T C ) the alloy reveals an extremely intensive signal of CESR, which suggests a high concentration of conduction electrons and correlates with the large value of the magnetic-field-induced strain observed in the alloys of such composition. The temperature dependence of the skin layer depth is found from the sharp decay of the CESR signal with temperature, which is related to the disappearing large magnetic resistance after transformation to the paramagnetic state

  13. Optimized quantum sensing with a single electron spin using real-time adaptive measurements

    Science.gov (United States)

    Bonato, C.; Blok, M. S.; Dinani, H. T.; Berry, D. W.; Markham, M. L.; Twitchen, D. J.; Hanson, R.

    2016-03-01

    Quantum sensors based on single solid-state spins promise a unique combination of sensitivity and spatial resolution. The key challenge in sensing is to achieve minimum estimation uncertainty within a given time and with high dynamic range. Adaptive strategies have been proposed to achieve optimal performance, but their implementation in solid-state systems has been hindered by the demanding experimental requirements. Here, we realize adaptive d.c. sensing by combining single-shot readout of an electron spin in diamond with fast feedback. By adapting the spin readout basis in real time based on previous outcomes, we demonstrate a sensitivity in Ramsey interferometry surpassing the standard measurement limit. Furthermore, we find by simulations and experiments that adaptive protocols offer a distinctive advantage over the best known non-adaptive protocols when overhead and limited estimation time are taken into account. Using an optimized adaptive protocol we achieve a magnetic field sensitivity of 6.1 ± 1.7 nT Hz-1/2 over a wide range of 1.78 mT. These results open up a new class of experiments for solid-state sensors in which real-time knowledge of the measurement history is exploited to obtain optimal performance.

  14. Systematic study on nuclear resonant scattering

    International Nuclear Information System (INIS)

    Suarez, A.A.; Freitas, M.L.

    1974-01-01

    New resonant scattering effect of thermal neutron capture gamma rays from Ti and Fe on Sb, Cu, Se and Ce target were observed. These results together with those published by other authors are summarized and discussed in terms of a possible systematic search for new resonant scattering effects

  15. Study of spin resonances in the accelerators with snakes

    International Nuclear Information System (INIS)

    Lee, S.Y.

    1989-01-01

    Spin resonances in the circular accelerators with snakes are studied to understand the nature of snake resonances. We analyze the effect of snake configuration, and the snake superperiod on the resonance. Defining the critical resonance strength ε c as the maximum tolerable resonance strength without losing the beam polarization after passing through the resonance, we found that ε c is a sensitive function of the snake configuration, the snake superperiod at the first order snake resonance, the higher order snake resonance conditions and the spin matching condition. Under properly designed snake configuration, the critical resonance strength ε c is found to vary linearly with N S as left-angle ε c right-angle=(1/π)sin -1 (cos πν z | 1/2 )N S , where ν| z and N S are the betatron tune and the number of snakes respectively. We also study the effect of overlapping intrinsic and imperfection resonances. The imperfection resonance should be corrected to a magnitude of insignificance (e.g., ε≤0.1 for two snakes case) to maintain proper polarization

  16. Entanglement dynamics of two electron-spin qubits in a strongly detuned and dissipative quantum-dot-cavity system

    International Nuclear Information System (INIS)

    Xiang Shaohua; Deng Xiaopeng; Song Kehui; Wen Wei; Shi Zhengang

    2011-01-01

    We investigate the entanglement dynamics of two electron-spin qubits in the quantum-dot (QD)-microcavity system in the large-detuning limit and subjected to two different noise sources: electron-spin dephasing and relaxation. We show that when one of the two dots is prepared initially in the excited state, the created entanglement exhibits oscillatory behavior at the beginning of evolution and then completely disappears over time. For two QDs that are initially in either the Einstein-Podolsky-Rosen-Bell states or the Werner states, their entanglement evolution exhibits the same behavior in the presence of pure dephasing, but is completely different under the relaxation process. We also show that the interdot interaction induced by a single-mode cavity field does not contribute to the dynamics of entanglement for these Bell states and Werner states.

  17. Resonance Raman study of benzyl radical

    DEFF Research Database (Denmark)

    Langkilde, F.W.; Bajdor, K.; Wilbrandt, R.

    1992-01-01

    Time-resolved resonance Raman spectra are obtained of benzyl radicals created by laser flash photolysis of benzylchloride and diphenylacetone in solution. The spectra are obtained in resonance with the intense 2 2A2-1 B-2(2) transition of benzyl. The strong Raman bands are assigned to totally...... symmetric a1 modes. The remaining observed bands are tentatively assigned to fundamental modes of b1, a2, and b2 symmetry, and to overtones and combinations. The resonance Raman spectra are found to be quite different from previous fluorescence spectra of benzyl, and the origins of these differences...

  18. Optimization of a Solid-State Electron Spin Qubit Using Gate Set Tomography (Open Access, Publisher’s Version)

    Science.gov (United States)

    2016-10-13

    and addressedwhen the qubit is usedwithin a fault-tolerant quantum computation scheme. 1. Introduction One of themain challenges in the physical...supplied in the supplementarymaterial. Additionally, we have supplied the datafiles constructed from the experiments, alongwith the Python notebook used to...New J. Phys. 18 (2016) 103018 doi:10.1088/1367-2630/18/10/103018 PAPER Optimization of a solid-state electron spin qubit using gate set tomography

  19. Single-shot quantum nondemolition measurement of a quantum-dot electron spin using cavity exciton-polaritons

    Science.gov (United States)

    Puri, Shruti; McMahon, Peter L.; Yamamoto, Yoshihisa

    2014-10-01

    We propose a scheme to perform single-shot quantum nondemolition (QND) readout of the spin of an electron trapped in a semiconductor quantum dot (QD). Our proposal relies on the interaction of the QD electron spin with optically excited, quantum well (QW) microcavity exciton-polaritons. The spin-dependent Coulomb exchange interaction between the QD electron and cavity polaritons causes the phase and intensity response of left circularly polarized light to be different than that of right circularly polarized light, in such a way that the QD electron's spin can be inferred from the response to a linearly polarized probe reflected or transmitted from the cavity. We show that with careful device design it is possible to essentially eliminate spin-flip Raman transitions. Thus a QND measurement of the QD electron spin can be performed within a few tens of nanoseconds with fidelity ˜99.95%. This improves upon current optical QD spin readout techniques across multiple metrics, including speed and scalability.

  20. Resonance

    DEFF Research Database (Denmark)

    Petersen, Nils Holger

    2014-01-01

    A chapter in a book about terminology within the field of medievalism: the chapter discusses the resonance of medieval music and ritual in modern (classical) music culture and liturgical practice.......A chapter in a book about terminology within the field of medievalism: the chapter discusses the resonance of medieval music and ritual in modern (classical) music culture and liturgical practice....

  1. Loophole-free Bell inequality violation using electron spins separated by 1.3 kilometres

    Science.gov (United States)

    Hensen, B.; Bernien, H.; Dréau, A. E.; Reiserer, A.; Kalb, N.; Blok, M. S.; Ruitenberg, J.; Vermeulen, R. F. L.; Schouten, R. N.; Abellán, C.; Amaya, W.; Pruneri, V.; Mitchell, M. W.; Markham, M.; Twitchen, D. J.; Elkouss, D.; Wehner, S.; Taminiau, T. H.; Hanson, R.

    2015-10-01

    More than 50 years ago, John Bell proved that no theory of nature that obeys locality and realism can reproduce all the predictions of quantum theory: in any local-realist theory, the correlations between outcomes of measurements on distant particles satisfy an inequality that can be violated if the particles are entangled. Numerous Bell inequality tests have been reported; however, all experiments reported so far required additional assumptions to obtain a contradiction with local realism, resulting in `loopholes'. Here we report a Bell experiment that is free of any such additional assumption and thus directly tests the principles underlying Bell's inequality. We use an event-ready scheme that enables the generation of robust entanglement between distant electron spins (estimated state fidelity of 0.92 +/- 0.03). Efficient spin read-out avoids the fair-sampling assumption (detection loophole), while the use of fast random-basis selection and spin read-out combined with a spatial separation of 1.3 kilometres ensure the required locality conditions. We performed 245 trials that tested the CHSH-Bell inequality S memory in the devices. Our data hence imply statistically significant rejection of the local-realist null hypothesis. This conclusion may be further consolidated in future experiments; for instance, reaching a value of P = 0.001 would require approximately 700 trials for an observed S = 2.4. With improvements, our experiment could be used for testing less-conventional theories, and for implementing device-independent quantum-secure communication and randomness certification.

  2. Low-frequency ESR studies on permeable and impermeable deuterated nitroxyl radicals in corn oil solution.

    Science.gov (United States)

    David Jebaraj, D; Utsumi, Hideo; Milton Franklin Benial, A

    2018-04-01

    Low-frequency electron spin resonance studies were performed for 2 mM concentration of deuterated permeable and impermeable nitroxyl spin probes, 3-methoxycarbonyl-2,2,5,5-tetramethyl-pyrrolidine-1-oxyl and 3-carboxy-2,2,5,5,-tetramethyl-1-pyrrolidinyloxy in pure water and various concentrations of corn oil solution. The electron spin resonance parameters such as the line width, hyperfine coupling constant, g factor, rotational correlation time, permeability, and partition parameter were estimated. The broadening of line width was observed for nitroxyl radicals in corn oil mixture. The rotational correlation time increases with increasing concentration of corn oil, which indicates the less mobile nature of spin probe in corn oil mixture. The membrane permeability and partition parameter values were estimated as a function of corn oil concentration, which reveals that the nitroxyl radicals permeate equally into the aqueous phase and oil phase at the corn oil concentration of 50%. The electron spin resonance spectra demonstrate the permeable and impermeable nature of nitroxyl spin probes. From these results, the corn oil concentration was optimized as 50% for phantom studies. In this work, the corn oil and pure water mixture phantom models with various viscosities correspond to plasma membrane, and whole blood membrane with different hematocrit levels was studied for monitoring the biological characteristics and their interactions with permeable nitroxyl spin probe. These results will be useful for the development of electron spin resonance and Overhauser-enhanced magnetic resonance imaging modalities in biomedical applications. Copyright © 2017 John Wiley & Sons, Ltd.

  3. Eigenvalue study of a chaotic resonator

    Energy Technology Data Exchange (ETDEWEB)

    Banova, Todorka [Technische Universitaet Darmstadt, Institut fuer Theorie Elektromagnetischer Felder (TEMF), Schlossgartenstrasse 8, D-64289 Darmstadt (Germany); Technische Universitaet Darmstadt, Graduate School of Computational Engineering, Dolivostrasse 15, D-64293 Darmstadt (Germany); Ackermann, Wolfgang; Weiland, Thomas [Technische Universitaet Darmstadt, Institut fuer Theorie Elektromagnetischer Felder (TEMF), Schlossgartenstrasse 8, D-64289 Darmstadt (Germany)

    2013-07-01

    The field of quantum chaos comprises the study of the manifestations of classical chaos in the properties of the corresponding quantum systems. Within this work, we compute the eigenfrequencies that are needed for the level spacing analysis of a microwave resonator with chaotic characteristics. The major challenges posed by our work are: first, the ability of the approaches to tackle the large scale eigenvalue problem and second, the capability to extract many, i.e. order of thousands, eigenfrequencies for the considered cavity. The first proposed approach for an accurate eigenfrequency extraction takes into consideration the evaluated electric field computations in time domain of a superconducting cavity and by means of signal-processing techniques extracts the eigenfrequencies. The second approach is based on the finite element method with curvilinear elements, which transforms the continuous eigenvalue problem to a discrete generalized eigenvalue problem. Afterwards, the Lanczos algorithm is used for the solution of the generalized eigenvalue problem. In the poster, a summary of the applied algorithms, as well as, critical implementation details together with the simulation results are provided.

  4. Nuclear magnetic resonance studies of metabolic regulation

    International Nuclear Information System (INIS)

    Sillerud, L.O.; Han, C.H.; Whaley, T.W.

    1983-01-01

    Nuclear magnetic resonance (NMR) techniques for the detection of the metabolic transformations of biological compounds labeled with stable isotopes, particularly carbon-13 have been explored. We have studied adipose tissue in the intact rat, the exteriorized epididymal fat pad, and the isolated adipocyte. Triacylglycerol metabolism in adipose tissue is regulated by lipogenic factors (insulin, corticosterone, thyroxine, and growth hormone) and lipolytic factors (glucagon and catecholamines). The synthesis of triglyceride from 5.5 mM glucose was stimulated by about 4-fold by 10 nM insulin. Triglyceride synthesis from glucose in the presence of insulin occurred at a rate of 330 nmol/hr/10 6 cells. Since the NMR signals from free and esterified fatty acids and glycerol are distinct, we could directly measure the rate of hormone-stimulated lipolysis. Epinephrine (10 μM) gave a lipolytic rate of 0.30 μmol/hr/10 6 cells as monitored by free-glycerol appearance in the medium. 13 C NMR provides a superior method for the measurement of triglyceride metabolism since it directly measures the changes in the substrates and products in situ

  5. Nuclear magnetic resonance studies of lipoproteins

    International Nuclear Information System (INIS)

    Hamilton, J.A.; Morrisett, J.D.

    1986-01-01

    Several nuclei in lipoproteins are magnetically active and are thus potential NMR probes of lipoprotein structure. Table I lists the magnetic isotopes preset in the covalent structures of the molecular constituents of lipoproteins: lipids, proteins, and carbohydrates. Every type of nucleus that is part of the endogenous structure of these molecules has at least one magnetic isotope. Each magnetic nucleus represents an intrinsic and completely nonperturbing probe (when at the natural abundance level) of local molecular motion and magnetic environment. The NMR experiment itself is also nonperturbing and nondestructive. Table I also lists for each nucleus its nuclear spin, its natural isotopic abundance, its sensitivity, and its resonance frequency at two commonly employed magnetic in the low field range (21.14 kG or 2.11 Tesla) and the other in the high field range (47.0 kG or 4.70 Tesla). Of the nuclei listed in Table I, /sup 1/H, /sup 13/C, and /sup 31/P have been the primary ones studied in lipoproteins. The general advantages and disadvantages afforded by these and other nuclei as probes of lipoprotein structure are discussed. /sup 13/C NMR spectroscopy, the method which has had the most extensive application (and probably has the greatest future potential) to lipoproteins, is treated in greatest detail, but many of the principles described apply to other nuclei as well

  6. Nuclear magnetic resonance studies of lens transparency

    International Nuclear Information System (INIS)

    Beaulieu, C.F.

    1989-01-01

    Transparency of normal lens cytoplasm and loss of transparency in cataract were studied by nuclear magnetic resonance (NMR) methods. Phosphorus ( 31 P) NMR spectroscopy was used to measure the 31 P constituents and pH of calf lens cortical and nuclear homogenates and intact lenses as a function of time after lens enucleation and in opacification produced by calcium. Transparency was measured with laser spectroscopy. Despite complete loss of adenosine triphosphate (ATP) within 18 hrs of enucleation, the homogenates and lenses remained 100% transparent. Additions of calcium to ATP-depleted cortical homogenates produced opacification as well as concentration-dependent changes in inorganic phosphate, sugar phosphates, glycerol phosphorylcholine and pH. 1 H relaxation measurements of lens water at 200 MHz proton Larmor frequency studied temperature-dependent phase separation of lens nuclear homogenates. Preliminary measurements of T 1 and T 2 with non-equilibrium temperature changes showed a change in the slope of the temperature dependence of T 1 and T 2 at the phase separation temperature. Subsequent studies with equilibrium temperature changes showed no effect of phase separation on T 1 or T 2 , consistent with the phase separation being a low-energy process. 1 H nuclear magnetic relaxation dispersion (NMRD) studies (measurements of the magnetic field dependence of the water proton 1/T 1 relaxation rates) were performed on (1) calf lens nuclear and cortical homogenates (2) chicken lens homogenates, (3) native and heat-denatured egg white and (4) pure proteins including bovine γ-II crystallin bovine serum albumin (BSA) and myoglobin. The NMRD profiles of all samples exhibited decreases in 1/T 1 with increasing magnetic field

  7. Deep-level defects in semiconductors: studies by magnetic resonance

    International Nuclear Information System (INIS)

    Ammerlaan, C.A.J.

    1983-01-01

    This work is divided into two parts. In the first one, the following topics are discussed: paramagnetic centers in semiconductors, principles of magnetic resonance, spin-Hamiltonian, g-tensor, hyperfine interaction, magnetic resonance spectrometer. In the second part it is dicussed defects studied by magnetic resonance including vacancy and divacancy in silicon, iron in silicon, nitrogen in diamond and antisite defects in III-V compounds. (A.C.A.S.) [pt

  8. Simulation study of resonant reflector for S-band BWO

    International Nuclear Information System (INIS)

    Choyal, Y; Parmar, Nidhi; Saini, Ajay Kumar; Chhotray, S K; Bhat, K S; Kumar, Lalit

    2012-01-01

    This paper presents the result of simulation studies of resonant reflector used for reflection of backward wave in relativistic BWO. The resonant reflector is modelled and analyzed by CST MWS for TM 01 . A TM 01 mode is fed at the output end of the BWO and signal is observed at the cathode end. Results show that 90 percent of the backward TM 01 wave is get reflected back by the locked TM 02 mode in the resonant reflector.

  9. Investigation of magnetic interactions in sulfides by means of magnetic resonance

    International Nuclear Information System (INIS)

    Veen, G. van.

    1978-01-01

    Investigations have been designed to gather more information about magnetic pair interactions in sulfides by isomorphic substitution of the magnetic ions in suitable chosen diamagnetic host lattices and measurement of electron spin resonance of coupled pairs and of electron spin resonance or electron nuclear double resonance of the hyperfine interaction due to the nuclei of diamagnetic cations. The greater part of this thesis is devoted to preliminaries of magnetic resonance interpretation and sample selection and preparation. The measurements on the magnetically diluted compounds, which are described, only have an exploratory nature. (Auth.)

  10. Multichannel approach to studying scalar resonances

    International Nuclear Information System (INIS)

    Krupa, D.; Surovtsev, Yu.S.

    1995-11-01

    The multichannel approach to the investigation of resonances is given in order to determine their quantum chromodynamical nature. The formula for the analytic continuation of the N-channel S-matrix to the unphysical sheets of the Riemann surface is given, which is a solution of the N-channel problem in that it enables a prediction of the coupled-process amplitudes on the uniformization plane of the S-matrix. The resonance representations by pairs of complex-conjugate clusters of poles and zeros on the Riemann surface are discussed. The concept of standard clusters as model-independent characteristics of the resonance is developed. 32 refs, 5 figs, 4 tabs

  11. Study of giant resonances in heavy nuclei

    International Nuclear Information System (INIS)

    Cataldi, M.I.C.

    1986-01-01

    The electrodisintegration cross section for 181 Ta, 208 Pb and 209 Bi was measured by counting the emitted neutrons, with incident electrons in the energy range 8-22 MeV. The data was analysed using the virtual photon method, in order to obtain a multipole decomposition and the intensities of Magnetic Dipole and Electric Quadrupole, isoscalar and isovector, in the Giant Resonance. The results obtained for the isovector Giant Quadrupole Resonance are compared with the measured photodisintegration cross section, using data from Saclay and Livermore. This comparision indicates that the photodisintegration data can be well explained assuming an isovector E2 Resonance located between 120 and 130 A -1/3 MeV, with an intensity of one isovector E2 sum. (author) [pt

  12. Resonant Auger studies of metallic systems

    International Nuclear Information System (INIS)

    Coulthard, I.; Antel, W. J. Jr.; Frigo, S. P.; Freeland, J. W.; Moore, J.; Calaway, W. S.; Pellin, M. J.; Mendelsohn, M.; Sham, T. K.; Naftel, S. J.

    2000-01-01

    Results of resonant Auger spectroscopy experimental are presented for Cu, Co, and oxidized Al. Sublifetime narrowing of Auger spectra and generation of sublifetime narrowed absorption spectra constructed from Auger yield measurements were observed. Resonant Auger yields are used to identify three chemical states of oxidized Al. Partial absorption yield spectra were derived giving detailed electronic information and thickness information for the various chemical states of the bulk metal, the passivating aluminum oxide layer, and the metal-oxide interface region. In addition, the total absorption yield spectrum for the oxidized Al sample was constructed from the partial yield data, supporting the consistency of our method. (c) 2000 American Vacuum Society

  13. Study on Dynamic Alignment Technology of COIL Resonator

    International Nuclear Information System (INIS)

    Xiong, M D; Zou, X J; Guo, J H; Jia, S N; Zhang, Z B

    2006-01-01

    The performance of great power chemical oxygen-iodine laser (COIL) beam is decided mostly by resonator mirror maladjustment and environment vibration. To improve the performance of light beam, an auto-alignment device is used in COIL resonator, the device can keep COIL resonator collimating by adjusting the optical components of resonator. So the coupling model of COIL resonator is present. The multivariable self study fuzzy uncoupling arithmetic and six-dimensional micro drive technology are used to design a six-input-three-output uncoupling controller, resulting in the realization of the high precision dynamic alignment. The experiments indicate that the collimating range of this system is 8 mrad, precision is 5 urad and frequency response is 20Hz, which meet the demand of resonator alignment system

  14. Study of giant resonances with pions

    International Nuclear Information System (INIS)

    Baer, H.W.

    1984-01-01

    Recent results on giant resonances obtained with pion-inelastic scattering and with single- and double-charge-exchange scattering are reviewed. The states discussed are isobaric analog states, double-isobaric analog states, and isovector L = 0, 1, and 2 collective states. 36 references

  15. Theoretical study of the electron paramagnetic resonance ...

    Indian Academy of Sciences (India)

    conveniently investigated by means of electron paramagnetic resonance (EPR). In ... ion Ir2+ can experience the Jahn–Teller effect by means of vibration interaction, ... Similarly, k. (and k ) are the orbital reduction factors arising from the anisotropic interactions of the orbital angular momentum operator. From the cluster ...

  16. A Study on Measurement Variations in Resonant Characteristics of Electrostatically Actuated MEMS Resonators

    Directory of Open Access Journals (Sweden)

    Faisal Iqbal

    2018-04-01

    Full Text Available Microelectromechanical systems (MEMS resonators require fast, accurate, and cost-effective testing for mass production. Among the different test methods, frequency domain analysis is one of the easiest and fastest. This paper presents the measurement uncertainties in electrostatically actuated MEMS resonators, using frequency domain analysis. The influence of the applied driving force was studied to evaluate the measurement variations in resonant characteristics, such as the natural frequency and the quality factor of the resonator. To quantify the measurement results, measurement system analysis (MSA was performed using the analysis of variance (ANOVA method. The results demonstrate that the resonant frequency ( f r is mostly affected by systematic error. However, the quality (Q factor strongly depends on the applied driving force. To reduce the measurement variations in Q factor, experiments were carried out to study the influence of DC and/or AC driving voltages on the resonator. The results reveal that measurement uncertainties in the quality factor were high for a small electrostatic force.

  17. Characterization of the oleic acid/iron oxide nanoparticle interface by magnetic resonance

    Energy Technology Data Exchange (ETDEWEB)

    Masur, S., E-mail: sabrina.masur@uni-due.de; Zingsem, B.; Marzi, T.; Meckenstock, R.; Farle, M.

    2016-10-01

    The synthesis of colloidal nanoparticles involves surfactant molecules, which bind to the particle surface and stabilize nanoparticles against aggregation. In many cases these protecting shells also can be used for further functionalization. In this study, we investigated monodisperse single crystalline iron oxide core/shell nanoparticles (Fe{sub x}O{sub y}-NPs) in situ covered with an oleic acid layer which showed two electron spin resonance (ESR) signals. The nanoparticles with the ligands attached were characterized by transmission electron microscopy (TEM) and ferro- and paramagnetic resonance (FMR, EPR). Infrared spectroscopy confirmed the presence of the functional groups and revealed that the oleic acid (OA) is chemisorbed as a carboxylate on the iron oxide and is coordinated symmetrically to the oxide atoms. We show that the EPR signal of the OA ligand molecule can be used as a local probe to determine the temperature changes at the surface of the nanoparticle. - Highlights: • Monodisperse single crystalline iron oxide core/shell nanoparticles (Fe{sub x}O{sub y}-NPs) in situ covered with an oleic acid layer two electron spin resonance (ESR) signals. • We show that the EPR signal of the OA ligand molecule can be used as a local probe to determine the temperature changes at the surface of the nanoparticle.

  18. Dielectric studies of fluids with reentrant resonators

    International Nuclear Information System (INIS)

    Goodwin, A.R.H.; Moldover, M.R.

    1993-01-01

    The authors have used a reentrant radio-frequency (rf) cavity as a resonator operating near 375 MHz to measure changes in the dielectric constant of fluids within it. The utility of these measurements was demonstrated by determining the dipole moment of 1,1,1,2,3,3-hexafluoropropane, a candidate replacement refrigerant (denoted R236ea) and by detecting the phase boundaries in the mixture [(1-x)C 2 H 6 + xCO 2 ], for the mole fraction x = 0.492. The densities of the coexisting phases of the mixture were determined using the Clausius-Mossotti relation which has errors on the order of 0.5% in this application. To test the accuracy of the present techniques, the rf resonator was calibrated with helium and then used to redetermine the molar polarizability A e of argon. The results were in excellent agreement with published values. The design of the reentrant resonator makes it suitable for use with corrosive fluids at temperature up to 400 degrees C

  19. Contribution to the study of electron paramagnetic resonance and relaxation

    International Nuclear Information System (INIS)

    Theobald, Jean-Gerard

    1962-01-01

    This research thesis reports an experimental work which comprises the development of a very practical and very sensitive electron paramagnetic resonance spectrometer, and the use of this equipment for the study of irradiated substances and carbons. By studying electronic resonance signals by fast modulation of the magnetic field, the author studied phenomena of quick passage in electronic resonance, and showed that the study of these phenomena requires observation systems with a particularly large bandwidth. He reports the measurement of the line width of packs of spins of inhomogeneous lines by two different methods [fr

  20. Electron spin relaxation enhancement measurements of interspin distances in human, porcine, and Rhodobacter electron transfer flavoprotein ubiquinone oxidoreductase (ETF QO)

    Science.gov (United States)

    Fielding, Alistair J.; Usselman, Robert J.; Watmough, Nicholas; Simkovic, Martin; Frerman, Frank E.; Eaton, Gareth R.; Eaton, Sandra S.

    2008-02-01

    Electron transfer flavoprotein-ubiquinone oxidoreductase (ETF-QO) is a membrane-bound electron transfer protein that links primary flavoprotein dehydrogenases with the main respiratory chain. Human, porcine, and Rhodobacter sphaeroides ETF-QO each contain a single [4Fe-4S] 2+,1+ cluster and one equivalent of FAD, which are diamagnetic in the isolated enzyme and become paramagnetic on reduction with the enzymatic electron donor or with dithionite. The anionic flavin semiquinone can be reduced further to diamagnetic hydroquinone. The redox potentials for the three redox couples are so similar that it is not possible to poise the proteins in a state where both the [4Fe-4S] + cluster and the flavoquinone are fully in the paramagnetic form. Inversion recovery was used to measure the electron spin-lattice relaxation rates for the [4Fe-4S] + between 8 and 18 K and for semiquinone between 25 and 65 K. At higher temperatures the spin-lattice relaxation rates for the [4Fe-4S] + were calculated from the temperature-dependent contributions to the continuous wave linewidths. Although mixtures of the redox states are present, it was possible to analyze the enhancement of the electron spin relaxation of the FAD semiquinone signal due to dipolar interaction with the more rapidly relaxing [4Fe-4S] + and obtain point-dipole interspin distances of 18.6 ± 1 Å for the three proteins. The point-dipole distances are within experimental uncertainty of the value calculated based on the crystal structure of porcine ETF-QO when spin delocalization is taken into account. The results demonstrate that electron spin relaxation enhancement can be used to measure distances in redox poised proteins even when several redox states are present.

  1. Resonances

    DEFF Research Database (Denmark)

    an impetus or drive to that account: change, innovation, rupture, or discontinuity. Resonances: Historical Essays on Continuity and Change explores the historiographical question of the modes of interrelation between these motifs in historical narratives. The essays in the collection attempt to realize...

  2. A new regional group of the lower paleolithic in Brittany (France), recently dated by electron spin resonance

    International Nuclear Information System (INIS)

    Monnier, J.L.; Hinguant, S.; Gebhardt, A.; Marguerie, D.; Molines, N.; Morzadec, H.; Hallegouet, B.; Laurent, M.; Auguste, P.; Bahain, J.J.; Falgueres, C.; Yokoyama, Y.

    1994-01-01

    ESR dates obtained at Menez-Dregan 1 (Brittany, France) focus interest on this Lower Paleolithic site and demonstrate that the preserved anthropic combustion structures are among the oldest known in the world. It allows the dating not only of the little known 'Colombanian Group' (it is an 'archaic' original group characterized by many choppers and very few handaxes, different from the Acheulian), but also, for the first time, of the old beaches on the southern coast of Brittany. Preserved bone remains are also very infrequent in Palaeolithic sites of Western France. The dating of the paleolithic layer at the top of the third fossil beach can be connected with isotopic stage 11 or the beginning of isotopic stage 10; it shows that the age of the geological and archaeological layers of Menez-Dregan 1 is probably between 350.000 and 500.000 years

  3. Detection of free radicals in gamma-irradiated soybean paste and model system by electron spin resonance spectroscopy

    International Nuclear Information System (INIS)

    Lee, E.-J.; Volkov, Vitaly I.; Byun, M.-W.; Lee, C.-H.

    2002-01-01

    We have investigated ESR spectra of fermented soybean paste irradiated at 77 K and compared with those of soybean protein isolate and soybean oil. The influences of irradiation dose, moisture content and heating after irradiation on the free radical concentration and species were examined. Four different carbon type free radicals, FR1-FR4, were identified as the product of amino acid decomposition. In the case of FR1, the doublet line arises from the hydrogen atom on the β-carbon adjacent to the carbonyl free radical. It disappeared at 150 K. FR2 was most abundant and disappeared at 190 K in wet soybean paste (WSP) and at 210 K in dry soybean paste (DSP), respectively. The radical FR4 originated from decarboxylation and deamination of amino acids, which disappeared at 210 K in both WSP and DSP. FR3 was assumed to be formed by the damage of amino acid side chains. The radical · OH was originated from water molecules, and was not observed in dry system. Sulfur radical was stable even at room temperature observed in both wet and dry systems. Aldehyde radical must be originated from the chemical reactions of enzymatic hydrolysates of soybean

  4. Electron spin resonance dating of human teeth from Toca da Santa shelter of Sao Raimundo Nonato, Piaui, Brazil

    Energy Technology Data Exchange (ETDEWEB)

    Kinoshita, A. [Faculdade de Filosofia, Ciencias e Letras de Ribeirao Preto, Universidade de Sao Paulo, Av. Bandeirantes, 3900, 14040-901 Ribeirao Preto, SP (Brazil); Universidade do Sagrado Coracao, Rua Irma Arminda 10-50, 17011-160 Bauru, SP (Brazil); Figueiredo, A.M.G. [Instituto de Pesquisas Energeticas e Nucleares (IPEN), Av. Lineu Prestes, 2242, Cidade Universitaria, 5422-970 Sao Paulo, SP (Brazil); Felice, G.D. [Fundacao Museu do Homem Americano-FUNDHAM, Rua Abdias Neves, no. 551, Centro, 64770-000 Sao Raimundo Nonato, Piaui (Brazil); Lage, M.C.S.M. [Universidade Federal do Piaui, Departamento de Quimica, Campus da Ininga, Ininga, 64049-550 Teresina, Piaui (Brazil); Guidon, N. [Fundacao Museu do Homem Americano-FUNDHAM, Rua Abdias Neves, no. 551, Centro, 64770-000 Sao Raimundo Nonato, Piaui (Brazil); Baffa, O. [Faculdade de Filosofia, Ciencias e Letras de Ribeirao Preto, Universidade de Sao Paulo, Av. Bandeirantes, 3900, 14040-901 Ribeirao Preto, SP (Brazil)], E-mail: baffa@usp.br

    2008-02-15

    Results of the dating of fossil human teeth excavated from a shelter in the surroundings areas of the Serra da Capivara National Park, Sao Raimundo Nonato, Piaui, Brazil are presented. This shelter was partially excavated to search for more data that could improve the archaeological context of the Garrincho's limestone hill sites, where the Toca do Gordo do Garrincho shelter provided two human teeth dated by conventional C-14 in (12,170 {+-} 40) yBP (years before present) and calibrated age (2 Sigma, 95% probability) 15,245-14,690 yBP (Beta 136204) [E. Peyre, C. Guerin, N. Guidon, I. Coppens, CR Acad. Sci. Paris, Sciences de la terre et des planetes/ Earth and Planetary Sciences 327 (1998) 335, ]. This region is challenging the classical theories about the peopling of America. In agreement with such theories the first human groups would have arrived in America, through Behring, only about 20,000 years ago. The site Toca do Boqueirao da Pedra Furada is a rock-shelter situated at the cliff that is the frontier between the Pre-Cambrian Sao Francisco plain and the Devonian-Permian highlands of the Maranhao-Piaui basin. It was excavated from 1978 till 1988 and presented a very consistent stratigraphy, with thousand of lithic implements and hearths [F. Parenti, Le gisement quaternaire de la Pedra Furada (Piaui, Bresil), Stratigraphie, chronologie, evolution culturelle, Editions Recherches sur les civilisations, Paris, 2002, ; F. Parenti, Le Gisement Quaternaire de la Toca do Boqueirao da Pedra Furada (Piaui, Bresil) dans le Contexte de la Prehistoire Americaine Fouilles, Stratigraphie, Chronologie, Evolution Culturelle, Ph.D. diss, Ecole des Hautes Etudes en Sciences Sociales, Paris, 1993, 411p, ; F. Parenti, M. Fontugne, N. Guidon, C. Guerin, M. Faure, Chronostratigraphie des gisements archeologiques et paleontologiques de Sao Raimundo Nonato (Piaui, Bresil): contribution a la connaissance du peuplement pleistocene de l'Amerique, Supplement de la Revue d'Archeometrie, 1999, p. 327, ]. Seventy C-14 dates were obtained going from 59,000 yBP to 5000 yBP at the actual soil [G.M. Santos, M.I., Bird, F. Parenti, L.K. Fifield, N. Guidon, P.A. Hausladen, Quaternary Sci. Rev. 22 (2003) 2303, ]. Beneath the date of 59,000 yBP it was found 1.5 m of archaeological layers, till the rock base. The cobbles that composed the structure of the hearths placed on top of the rock base were dated by thermoluminescence and the date of them is 100,000 yBP [H. Valladas, N. Mercier, M. Michab, J.L. Joron, J.L. Reiss, N. Guidon, N., Quaternary Sci. Rev. 22 (2003) 1257, ; H. Valladas, N. Mercier, M. Michab, J.L. Joron, J.L. Reyss, N. Guidon, Datacoes por Termoluminescencia de Seixos de Quartzo Queimados da Toca do Boqueirao da Pedra Furada (Piaui, Nordeste do Brasil), Fumdhamentos III, 1 (2003) 35 (in Portuguese), ]. Thus chronological information is of paramount importance to contextualize and to understand the many questions regarding the human occupation of these sites [N. Guidon, A.M. Pessis, G. Martin, O Povoamento Pre-Historico do Nordeste do Brasil, Proposta da: Fundacao Museu do Homem Americano, e do Nucleo de Estudos Arqueologicos, da UFPE, CLIO ARQ, Recife 1 (6) (1990) 123, ]. To obtain more information Toca da Santa shelter, the nearest site to Toca do Gordo do Garrincho shelter, was also excavated and three incomplete skeletons with teeth were found at 80 cm depth. The teeth were cleaned and acid etched and enamel completely removed from dentine and crushed in particles smaller than 0.5 mm. Enamel was irradiated with a Co-60 source and measured with an ESR spectrometer (X-band) to obtain the signal versus dose curve. The archeological doses obtained by the fitting were (5.94 {+-} 0.07) Gy and (5.97 {+-} 0.08) Gy. Using the ROSY program an age of 5,700 {+-} 200 yBP was found for both teeth.

  5. Identification of irradiated meat using electron spin resonance (ESR) spectroscopy and estimation of applied dose using re-irradiation

    International Nuclear Information System (INIS)

    Chawla, S.P.; Thomas, Paul; Bongirwar, D.R.

    2001-01-01

    An in-house blind trail on bone-in meat chunks was carried out in which 35 coded samples were correctly identified. The samples were either left unirradiated or had been irradiated to dose of 1, 2.5 or 4 kGy. Using re-irradiation, the dose received by the samples were determined with either linear, quadratic or exponential equation. The quadratic or exponential equation gave more successful estimates of irradiation dose whereas linear fit equations tend to over estimate the dose. (author)

  6. Electron spin resonance dating of human teeth from Toca da Santa shelter of Sao Raimundo Nonato, Piaui, Brazil

    International Nuclear Information System (INIS)

    Kinoshita, A.; Figueiredo, A.M.G.; Felice, G.D.; Lage, M.C.S.M.; Guidon, N.; Baffa, O.

    2008-01-01

    Results of the dating of fossil human teeth excavated from a shelter in the surroundings areas of the Serra da Capivara National Park, Sao Raimundo Nonato, Piaui, Brazil are presented. This shelter was partially excavated to search for more data that could improve the archaeological context of the Garrincho's limestone hill sites, where the Toca do Gordo do Garrincho shelter provided two human teeth dated by conventional C-14 in (12,170 ± 40) yBP (years before present) and calibrated age (2 Sigma, 95% probability) 15,245-14,690 yBP (Beta 136204) [E. Peyre, C. Guerin, N. Guidon, I. Coppens, CR Acad. Sci. Paris, Sciences de la terre et des planetes/ Earth and Planetary Sciences 327 (1998) 335, ]. This region is challenging the classical theories about the peopling of America. In agreement with such theories the first human groups would have arrived in America, through Behring, only about 20,000 years ago. The site Toca do Boqueirao da Pedra Furada is a rock-shelter situated at the cliff that is the frontier between the Pre-Cambrian Sao Francisco plain and the Devonian-Permian highlands of the Maranhao-Piaui basin. It was excavated from 1978 till 1988 and presented a very consistent stratigraphy, with thousand of lithic implements and hearths [F. Parenti, Le gisement quaternaire de la Pedra Furada (Piaui, Bresil), Stratigraphie, chronologie, evolution culturelle, Editions Recherches sur les civilisations, Paris, 2002, ; F. Parenti, Le Gisement Quaternaire de la Toca do Boqueirao da Pedra Furada (Piaui, Bresil) dans le Contexte de la Prehistoire Americaine Fouilles, Stratigraphie, Chronologie, Evolution Culturelle, Ph.D. diss, Ecole des Hautes Etudes en Sciences Sociales, Paris, 1993, 411p, ; F. Parenti, M. Fontugne, N. Guidon, C. Guerin, M. Faure, Chronostratigraphie des gisements archeologiques et paleontologiques de Sao Raimundo Nonato (Piaui, Bresil): contribution a la connaissance du peuplement pleistocene de l'Amerique, Supplement de la Revue d'Archeometrie, 1999, p. 327, ]. Seventy C-14 dates were obtained going from 59,000 yBP to 5000 yBP at the actual soil [G.M. Santos, M.I., Bird, F. Parenti, L.K. Fifield, N. Guidon, P.A. Hausladen, Quaternary Sci. Rev. 22 (2003) 2303, ]. Beneath the date of 59,000 yBP it was found 1.5 m of archaeological layers, till the rock base. The cobbles that composed the structure of the hearths placed on top of the rock base were dated by thermoluminescence and the date of them is 100,000 yBP [H. Valladas, N. Mercier, M. Michab, J.L. Joron, J.L. Reiss, N. Guidon, N., Quaternary Sci. Rev. 22 (2003) 1257, ; H. Valladas, N. Mercier, M. Michab, J.L. Joron, J.L. Reyss, N. Guidon, Datacoes por Termoluminescencia de Seixos de Quartzo Queimados da Toca do Boqueirao da Pedra Furada (Piaui, Nordeste do Brasil), Fumdhamentos III, 1 (2003) 35 (in Portuguese), ]. Thus chronological information is of paramount importance to contextualize and to understand the many questions regarding the human occupation of these sites [N. Guidon, A.M. Pessis, G. Martin, O Povoamento Pre-Historico do Nordeste do Brasil, Proposta da: Fundacao Museu do Homem Americano, e do Nucleo de Estudos Arqueologicos, da UFPE, CLIO ARQ, Recife 1 (6) (1990) 123, ]. To obtain more information Toca da Santa shelter, the nearest site to Toca do Gordo do Garrincho shelter, was also excavated and three incomplete skeletons with teeth were found at 80 cm depth. The teeth were cleaned and acid etched and enamel completely removed from dentine and crushed in particles smaller than 0.5 mm. Enamel was irradiated with a Co-60 source and measured with an ESR spectrometer (X-band) to obtain the signal versus dose curve. The archeological doses obtained by the fitting were (5.94 ± 0.07) Gy and (5.97 ± 0.08) Gy. Using the ROSY program an age of 5,700 ± 200 yBP was found for both teeth

  7. ESR study of thermal demagnetization processes in ferromagnetic nanoparticles with Curie temperatures between 40 and 60 deg. C

    Energy Technology Data Exchange (ETDEWEB)

    Kuznetsov, Oleg A. [Institute of Biochemical Physics, Russian Academy of Sciences (RAS), Kosygin St. 4, Moscow 119991 (Russian Federation)]. E-mail: kuznetsov_oa@yahoo.com; Sorokina, Olga N. [Institute of Biochemical Physics, Russian Academy of Sciences (RAS), Kosygin St. 4, Moscow 119991 (Russian Federation); Leontiev, Vladimir G. [Institute of Metallurgy, Russian Academy of Sciences (RAS), Moscow 119991 (Russian Federation); Shlyakhtin, Oleg A. [Institute of Chemical Physics, Russian Academy of Sciences (RAS), Kosygin St. 4, Moscow 119991 (Russian Federation); Kovarski, Alexander L. [Institute of Biochemical Physics, Russian Academy of Sciences (RAS), Kosygin St. 4, Moscow 119991 (Russian Federation); Kuznetsov, Anatoly A. [Institute of Biochemical Physics, Russian Academy of Sciences (RAS), Kosygin St. 4, Moscow 119991 (Russian Federation)

    2007-04-15

    Thermal demagnetization in the vicinity of the Curie temperature of silver and sodium manganite nanoparticles, as well as copper-nickel and palladium-nickel alloy nanoparticles were studied by both static magnetic measurements and by electron spin resonance (ESR). ESR data indicate that some magnetic ordering remains even above the Curie temperature, determined by static magnetometry. Mechanisms of thermal demagnetization in alloy nanoparticles appear to be different from that in manganites.

  8. ESR study of thermal demagnetization processes in ferromagnetic nanoparticles with Curie temperatures between 40 and 60 deg. C

    International Nuclear Information System (INIS)

    Kuznetsov, Oleg A.; Sorokina, Olga N.; Leontiev, Vladimir G.; Shlyakhtin, Oleg A.; Kovarski, Alexander L.; Kuznetsov, Anatoly A.

    2007-01-01

    Thermal demagnetization in the vicinity of the Curie temperature of silver and sodium manganite nanoparticles, as well as copper-nickel and palladium-nickel alloy nanoparticles were studied by both static magnetic measurements and by electron spin resonance (ESR). ESR data indicate that some magnetic ordering remains even above the Curie temperature, determined by static magnetometry. Mechanisms of thermal demagnetization in alloy nanoparticles appear to be different from that in manganites

  9. Coherent control of two individual electron spins and influence of hyperfine coupling in a double quantum dot

    International Nuclear Information System (INIS)

    Tarucha, S; Obata, T; Pioro-Ladriere, M; Brunner, R; Shin, Y-S; Kubo, T; Tokura, Y

    2011-01-01

    Electric dipole spin resonance of two individual electrons and the influence of hyperfine coupling on the spin resonance are studied for a double quantum dot equipped with a micro-magnet. The spin resonance occurs by oscillating the electron in each dot at microwave (MW) frequencies in the presence of a micro-magnet induced stray field. The observed continuous wave (CW) and time-resolved spin resonances are consistent with calculations in which the MW induced AC electric field and micro-magnet induced stray field are taken into account. The influence of hyperfine coupling causes an increase and broadening of the respective CW spin resonance peaks through dynamical nuclear polarization when sweeping up the magnetic field. This behaviour appears stronger for the larger of the two spin resonance peaks and in general becomes more pronounced as the MW power increases, both reflecting that the electron-nuclei interaction is more efficient for the stronger spin resonance. In addition the hyperfine coupling effect only becomes pronounced when the MW induced AC magnetic field exceeds the fluctuating nuclear field.

  10. Cerebral fat embolism: magnetic resonance study

    International Nuclear Information System (INIS)

    Guedea, A.; Barrena, R.; Guelbenzu, S.; Tejada, A.

    1998-01-01

    We report the case of 26-year-old man who presented clinical evidence of fat embolism following a traffic accident. Although computed tomography (CT) of the brain showed no abnormalities, magnetic resonance imaging (MRI) disclosed several scattered points of high intensity on T2-weighted and proton density (PD) images, with complete resolution of the lesions on follow-up scan. MRI is considered more sensitive than computed tomography in detecting these lesions, and may be useful for their diagnosis, correlating well with the clinical course. (Author) 10 refs

  11. Role of chelates in magnetic resonance imaging studies

    Directory of Open Access Journals (Sweden)

    Tripathi Laxmi

    2009-01-01

    Full Text Available Imaging studies are tests performed with a variety of techniques that produce pictures of the inside of a patient′s body. Magnetic resonance imaging (MRI is an imaging technique based on the principles of nuclear magnetic resonance. MRI uses a powerful magnetic field, radio waves, and a computer to produce detailed pictures of organs, soft tissues, bone, and virtually all other internal body structures. Chelates have a wide application in such imaging techniques. Chelates in imaging studies are used alone as radioactive agents or conjugated to monoclonal antibodies or to DNA as radioactive agents. Technetium chelates and gadolinium chelates are being widely used as magnetic resonance contrast media.

  12. The electron-spin--nuclear-spin interaction studied by polarized neutron scattering.

    Science.gov (United States)

    Stuhrmann, Heinrich B

    2007-11-01

    Dynamic nuclear spin polarization (DNP) is mediated by the dipolar interaction of paramagnetic centres with nuclear spins. This process is most likely to occur near paramagnetic centres at an angle close to 45 degrees with respect to the direction of the external magnetic field. The resulting distribution of polarized nuclear spins leads to an anisotropy of the polarized neutron scattering pattern, even with randomly oriented radical molecules. The corresponding cross section of polarized coherent neutron scattering in terms of a multipole expansion is derived for radical molecules in solution. An application using data of time-resolved polarized neutron scattering from an organic chromium(V) molecule is tested.

  13. Compact cryogenic Kerr microscope for time-resolved studies of electron spin transport in microstructures

    NARCIS (Netherlands)

    Rizo, P. J.; Pugzlys, A.; Liu, J.; Reuter, D.; Wieck, A. D.; van der Wal, C. H.; van Loosdrecht, P. H. M.; Pugžlys, A.

    2008-01-01

    A compact cryogenic Kerr microscope for operation in the small volume of high-field magnets is described. It is suited for measurements both in Voigt and Faraday configurations. Coupled with a pulsed laser source, the microscope is used to measure the time-resolved Kerr rotation response of

  14. Study of isobutyric acid reactivity by electron spin resonance and infrared spectroscopy of the sodium salt and of 1-vanado-11-molybdophosphoric acid; Etude de la reactivite de l`acide isobutyrique par spectroscopie infrarouge et resonance paramagnetique electronique du sel de sodium et de l`acide de l`ion 1-vanado-11-molybdophosphorique

    Energy Technology Data Exchange (ETDEWEB)

    Rabia, C.; Bettahar, M.M. [Universite des sciences et de technologies, Houari-Boumediene, Algiers (Algeria); Fournier, M. [Universite des Sciences et technologies de Lille, 59 - Villeneuve d`Ascq (France)

    1997-11-01

    The alkaline salt 1-vanado-11-molybdo-phosphore acid as been investigated in isobutyric absorption-desorption-re-oxidation cycles by IR and ESR spectroscopies in comparison to the bulk acid compound. The stability of the active phase in catalysis seems to be related to the formation of a cubic phase depending strongly on the presence of water vapor in the gas stream. This phase can be generated from an alkali precursor subject to a moderate thermal treatment leading to a dispersion of di-oxovanadium cation into the alkali-12-molybdophosphate lattice. (authors) 14 refs.

  15. Demonstration of quantum entanglement between a single electron spin confined to an InAs quantum dot and a photon.

    Science.gov (United States)

    Schaibley, J R; Burgers, A P; McCracken, G A; Duan, L-M; Berman, P R; Steel, D G; Bracker, A S; Gammon, D; Sham, L J

    2013-04-19

    The electron spin state of a singly charged semiconductor quantum dot has been shown to form a suitable single qubit for quantum computing architectures with fast gate times. A key challenge in realizing a useful quantum dot quantum computing architecture lies in demonstrating the ability to scale the system to many qubits. In this Letter, we report an all optical experimental demonstration of quantum entanglement between a single electron spin confined to a single charged semiconductor quantum dot and the polarization state of a photon spontaneously emitted from the quantum dot's excited state. We obtain a lower bound on the fidelity of entanglement of 0.59±0.04, which is 84% of the maximum achievable given the timing resolution of available single photon detectors. In future applications, such as measurement-based spin-spin entanglement which does not require sub-nanosecond timing resolution, we estimate that this system would enable near ideal performance. The inferred (usable) entanglement generation rate is 3×10(3) s(-1). This spin-photon entanglement is the first step to a scalable quantum dot quantum computing architecture relying on photon (flying) qubits to mediate entanglement between distant nodes of a quantum dot network.

  16. Probing the 4p electron-spin polarization in NiO

    International Nuclear Information System (INIS)

    Neubeck, W.; Vettier, C.; Bergevin, F. de; Yakhou, F.; Mannix, D.; Bengone, O.; Alouani, M.; Barbier, A.

    2001-01-01

    K-edge resonant x-ray magnetic scattering experiments have been performed on antiferromagnetic NiO. The observation of two resonances at the K edge allows the construction of models to compare the electronic properties of NiO and the observed resonant magnetic x-ray scattering. From the polarization analysis of the scattered beam, a quadrupolar transition (1s-3d) and a dipolar transition (1s-4p) are identified. While the quadrupolar transition can be modeled using an atomic picture for the 3d electrons, the dipolar transition is associated to a broadband structure of p electrons and its energy profile is compared to electronic band-structure calculations

  17. Depolarization of the electron spin in storage rings by nonlinear spin-orbit coupling

    International Nuclear Information System (INIS)

    Kewisch, J.

    1985-10-01

    Electrons and positrons which circulate in the storage ring are polarized at the emission of synchrotron radiation by the so called Sokolov-Ternov effect. This polarization is on the one hand of large interest for the study of the weak interaction, on the other hand it can be used for the accurate measurement of the beam energy and by this of the mass of elementary particles. The transverse and longitudinal particle vibrations simultaneously excited by the synchrotron radiation however can effect that this polarization is destroyed. This effect is called spin-orbit coupling. For the calculation of the spin-orbit coupling the computer program SITROS was written. This program is a tracking program: The motion of some sample particles and their spin vectors are calculated for some thousand circulations. From this the mean depolarization and by extrapolation the degree of polarization of the equilibrium state is determined. Contrarily to the known program SLIM which is based on perturbational calculations in SITROS the nonlinear forces in the storage ring can be regarded. By this the calculation of depolarizing higher order resonances is made possible. In this thesis the equations of motion for the orbital and spin motion of the electrons are derived which form the base for the program SITROS. The functions of the program and the approximations necessary for the saving of calculational time are explained. The comparison of the SITROS results with the measurement results obtained at the PETRA storage ring shows that the SITROS program is a useful means for the planning and calculation of storage rings with polarized electron beams. (orig.) [de

  18. Ferromagnetic resonance studies of lunar core stratigraphy

    Science.gov (United States)

    Housley, R. M.; Cirlin, E. H.; Goldberg, I. B.; Crowe, H.

    1976-01-01

    We first review the evidence which links the characteristic ferromagnetic resonance observed in lunar fines samples with agglutinatic glass produced primarily by micrometeorite impacts and present new results on Apollo 15, 16, and 17 breccias which support this link by showing that only regolith breccias contribute significantly to the characteristic FMR intensity. We then provide a calibration of the amount of Fe metal in the form of uniformly magnetized spheres required to give our observed FMR intensities and discuss the theoretical magnetic behavior to be expected of Fe spheres as a function of size. Finally, we present FMR results on samples from every 5 mm interval in the core segments 60003, 60009, and 70009. These results lead us to suggest: (1) that secondary mixing may generally be extensive during regolith deposition so that buried regolith surfaces are hard to recognize or define; and (2) that local grinding of rocks and pebbles during deposition may lead to short scale fluctuations in grain size, composition, and apparent exposure age of samples.

  19. Interaction of magnetic resonators studied by the magnetic field enhancement

    Directory of Open Access Journals (Sweden)

    Yumin Hou

    2013-12-01

    Full Text Available It is the first time that the magnetic field enhancement (MFE is used to study the interaction of magnetic resonators (MRs, which is more sensitive than previous parameters–shift and damping of resonance frequency. To avoid the coherence of lattice and the effect of Bloch wave, the interaction is simulated between two MRs with same primary phase when the distance is changed in the range of several resonance wavelengths, which is also compared with periodic structure. The calculated MFE oscillating and decaying with distance with the period equal to resonance wavelength directly shows the retardation effect. Simulation also shows that the interaction at normal incidence is sensitive to the phase correlation which is related with retardation effect and is ultra-long-distance interaction when the two MRs are strongly localized. When the distance is very short, the amplitude of magnetic resonance is oppressed by the strong interaction and thus the MFE can be much lower than that of single MR. This study provides the design rules of metamaterials for engineering resonant properties of MRs.

  20. Electron paramagnetic resonance: A new method of quaternary dating

    International Nuclear Information System (INIS)

    Poupeau, G.; Rossi, A.; Teles, M.M.; Danon, J.

    1984-01-01

    Significant progress has occurred in the last years in quaternary geochronology. One of this is the emergence of a new dating approach, the Electron Spin Resonance Method. The aim of this paper is to briefly review the method and discuss some aspects of the work at CBPF. (Author) [pt

  1. Electron paramagnetic resonance: a new method of quaternary dating

    International Nuclear Information System (INIS)

    Poupeau, G.; Rossi, A.; Universidade Federal Rural do Rio de Janeiro; Telles, M.; Danon, J.

    1984-01-01

    Significant progress has occurred in the last years in quaternary geochronology. One of this is the emergence of a new dating approach, the Electron Spin Resonance Method. The aim of this paper is to briefly review the method and discuss some aspects of the work at CBPF. (Author) [pt

  2. Magnetic Resonance Imaging Studies of Postpartum Depression: An Overview

    Directory of Open Access Journals (Sweden)

    Marco Fiorelli

    2015-01-01

    Full Text Available Postpartum depression is a frequent and disabling condition whose pathophysiology is still unclear. In recent years, the study of the neural correlates of mental disorders has been increasingly approached using magnetic resonance techniques. In this review we synthesize the results from studies on postpartum depression in the context of structural, functional, and spectroscopic magnetic resonance studies of major depression as a whole. Compared to the relative wealth of data available for major depression, magnetic resonance studies of postpartum depression are limited in number and design. A systematic literature search yielded only eleven studies conducted on about one hundred mothers with postpartum depression overall. Brain magnetic resonance findings in postpartum depression appear to replicate those obtained in major depression, with minor deviations that are not sufficient to delineate a distinct neurobiological profile for this condition, due to the small samples used and the lack of direct comparisons with subjects with major depression. However, it seems reasonable to expect that studies conducted in larger populations, and using a larger variety of brain magnetic resonance techniques than has been done so far, might allow for the identification of neuroimaging signatures for postpartum depression.

  3. Experimental study on moonpool resonance of offshore floating structure

    Directory of Open Access Journals (Sweden)

    Seung-Ho Yang

    2013-06-01

    Full Text Available Offshore floating structures have so-called moonpool in the centre area for the purpose of drilling, installation of subsea structures, recovery of Remotely-Operated Vehicle (ROV and divers. However, this vertical opening has an effect on the operating performance of floating offshore structure in the vicinity of moonpool resonance frequency; piston mode and sloshing mode. Experimental study based on model test was carried out. Moonpool resonance of floating offshore structure on fixed condition and motion free condition were investigated. And, the effect of cofferdam which is representative inner structure inside moonpool was examined. Model test results showed that Molin's theoretical formula can predict moonpool resonance on fixed condition quite accurately. However, motion free condition has higher resonance frequency when it is compared with that of motion fixed. The installation of cofferdam moves resonance frequency to higher region and also generates secondary resonance at lower frequency. Furthermore, it was found that cofferdam was the cause of generating waves in the longitudinal direction when the vessel was in beam sea.

  4. Experimental study of resonance crossing with a Paul trap

    Directory of Open Access Journals (Sweden)

    H. Takeuchi

    2012-07-01

    Full Text Available The effect of resonance crossing on beam stability is studied systematically by employing a novel tabletop experimental tool and a multiparticle simulation code. A large number of ions are confined in a compact linear Paul trap to reproduce the collective beam behavior. We can prove that the ion plasma in the trap is physically equivalent to a charged-particle beam propagating through a strong focusing channel. The plasma confinement force is quickly ramped such that the trap operating point traverses linear and nonlinear resonance stop bands. Assuming a nonscaling fixed field alternating gradient accelerator composed of many identical FODO cells, we measure how much ion losses occur under diverse conditions. It is experimentally and numerically demonstrated that too slow resonance crossing leads to significant ion losses as expected. Particular attention must be paid to the linear coherent resonance excited at a quarter-integer tune. When the beam intensity is high, this type of linear stop band can seriously affect the beam quality even for rather fast resonance crossing. A scaling law is given of the emittance growth caused by the quarter-integer resonance crossing.

  5. Resonant and Ground Experimental Study on the Microwave Plasma Thruster

    Science.gov (United States)

    Yang, Juan; He, Hongqing; Mao, Genwang; Qu, Kun; Tang, Jinlan; Han, Xianwei

    2002-01-01

    resonator, which reduces the energy loss arising from the heat conducting, the wall temperature almost have no limitation. The cavity is partitioned in two halves separated by a dialectic quartz plate. The propellant is swirl-injected tangentially in the nozzle side of the cavity (plasma chamber), which extends lifetime and working reliability of MPT. Compared, coaxial resonator has the characteristic of smaller structure, lighter weight, wider bandwidth of resonating frequency and more stable resonate state. microwave energy can heat propellant gas to produce thrust efficiently. According to the test method on the return loss of passive parts of microwave apparatus, this paper also makes experimental study on the resonating state of MPT cavity with scalar network analyzer operating under low signal. Purpose is to analyze its energy absorbing efficiency and resonant frequency band, research the matching of the cavity dimension, microwave coupling probe position and the isolate plate material within the cavity. The conclusion is helpful for the thruster design and improving the system efficiency. different propellant gases (Ar and He) have been fulfilled. The power, resonant pressure and mass flow rate have been measured and analyzed. Experiments show that MPT can start up reliably and work steadily. Keywords: microwave plasma thrustermicrowaveplasmaresonatorreturn loss

  6. A bias-tunable electron-spin filter based on a two-dimensional electron gas modulated by ferromagnetic-Schottky metal stripes

    Energy Technology Data Exchange (ETDEWEB)

    Lu Jianduo, E-mail: l_j316@163.co [Hubei Province Key Laboratory of Systems Science in Metallurgical Process, Wuhan University of Science and Technology, Wuhan 430081 (China); Li Yunbao; Yun Meijuan [Hubei Province Key Laboratory of Systems Science in Metallurgical Process, Wuhan University of Science and Technology, Wuhan 430081 (China); Zheng Wei [Key Laboratory of Dynamic Geodesy, Institute of Geodesy and Geophysics, Chinese Academy of Sciences, Wuhan 430077 (China)

    2011-03-28

    We investigate the effect of the bias in an electron-spin filter based on a two-dimensional electron gas modulated by ferromagnetic-Schottky metal stripes. The numerical results show that the electron transmission and the conductance as well as the spin polarization are strongly dependent on the bias applied to the device. - Research highlights: We propose a bias-tunable electron-spin filter. The transmission and the conductance depend on the bias and the electron energy. The spin polarization depends on the bias and the electron energy. The results are helpful for making new types of bias-tunable spin filters.

  7. Evidence of a spin resonance mode in the iron-based superconductor Ba(0.6)K(0.4)Fe2As2 from scanning tunneling spectroscopy.

    Science.gov (United States)

    Shan, Lei; Gong, Jing; Wang, Yong-Lei; Shen, Bing; Hou, Xingyuan; Ren, Cong; Li, Chunhong; Yang, Huan; Wen, Hai-Hu; Li, Shiliang; Dai, Pengcheng

    2012-06-01

    We used high-resolution scanning tunneling spectroscopy to study the hole-doped iron pnictide superconductor Ba(0.6)K(0.4)Fe(2)As(2) (T(c)=38 K). Features of a bosonic excitation (mode) are observed in the measured quasiparticle density of states. The bosonic features are intimately associated with the superconducting order parameter and have a mode energy of ~14 meV, similar to the spin resonance measured by inelastic neutron scattering. These results indicate a strong electron-spin excitation coupling in iron pnictide superconductors, similar to that in high-T(c) copper oxide superconductors.

  8. High-fidelity quantum gates on quantum-dot-confined electron spins in low-Q optical microcavities

    Science.gov (United States)

    Li, Tao; Gao, Jian-Cun; Deng, Fu-Guo; Long, Gui-Lu

    2018-04-01

    We propose some high-fidelity quantum circuits for quantum computing on electron spins of quantum dots (QD) embedded in low-Q optical microcavities, including the two-qubit controlled-NOT gate and the multiple-target-qubit controlled-NOT gate. The fidelities of both quantum gates can, in principle, be robust to imperfections involved in a practical input-output process of a single photon by converting the infidelity into a heralded error. Furthermore, the influence of two different decay channels is detailed. By decreasing the quality factor of the present microcavity, we can largely increase the efficiencies of these quantum gates while their high fidelities remain unaffected. This proposal also has another advantage regarding its experimental feasibility, in that both quantum gates can work faithfully even when the QD-cavity systems are non-identical, which is of particular importance in current semiconductor QD technology.

  9. Studies of magnetic resonance in anemia of hematies falciformes

    International Nuclear Information System (INIS)

    Lores Guevara, Manuel Arsenio; Balcom, Bruce John; Cabal Mirabal, Carlos

    2012-01-01

    Magnetic Resonance applications to the study of Sickle Cell Disease are analyzed using classical procedures and Unilateral Magnetic Resonance. Hemoglobin and whole blood samples were obtained from healthy individual and patients with Sickle Cell Anemia to be used as samples. Classical pulse sequence as spin echo and inversion recovery were used in the experimental studies, the STEPR method was used for EPR spectrometric determinations. The results show the possibility of NMR methods to follow the molecular process causing the disease and allows to present quantitative procedures to estimate the clinical state of the patients and the results of clinical options. We present the Unilateral Magnetic Resonance as a new method to study Sickle Cell disease considering its portability and new possibilities as new image method

  10. Temperature dependence of electron spin-lattice relaxation of radiation-produced silver atoms in polycrystalline aqueous and glassy organic matrices. Importance of relaxation by tunneling modes in disordered matrices

    International Nuclear Information System (INIS)

    Michalik, J.; Kevan, L.

    1978-01-01

    The electron spin-lattice relaxation of trapped silver atoms in polycrystalline ice matrices and in methanol, ethanol, propylene carbonate, and 2-methyltetrahydrofuran organic glasses has been directly studied as a function of temperature by the saturation-recovery method. Below 40 K the dominant electron spin-lattice relaxation mechanism involves modulation of the electron nuclear dipolar interaction with nuclei in the radical's environment by tunneling of those nuclei between two nearly equal energy configurations. This relaxation mechanism occurs with high efficiency, has a characteristic linear temperature dependence, and is typically found in highly disordered matrices. The efficiency of this relaxation mechanism seems to decrease with decreasing polarity of the matrix. Deuteration experiments show that the tunneling nuclei are protons and in methanol it is shown that the methyl protons have more tunneling modes available than the hydroxyl protons. In polycrystalline ice matrices silver atoms can be stabilized with two different orientations of surrounding water molecules; the efficiency of the tunneling relaxation reflects this difference. From these and previous results on tunneling relaxation of trapped electrons in glassy matrices it appears that tunneling relaxation may be used to distinguish models with different geometrical configurations and to determine the relative rigidity of such configurations around trapped radicals in disordered solids. (author)

  11. Magnetic resonance studies of solid polymers; Etude des polymeres solides par resonance magnetique

    Energy Technology Data Exchange (ETDEWEB)

    Lenk, R [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

    1969-07-01

    This paper is a review of the application of nuclear magnetic resonance (NMR) to solid polymers. In the first, theoretical part, the elements of the theory of NMR, which are necessary for the study of the properties of solid polymers are discussed: the moments method, nuclear relaxation and the distribution of correlation times. In the second part the experimental results are presented. (author) [French] Cette etude est une recherche bibliographique sur l'application de la resonance magnetique nucleaire (RMN) aux polymeres solides. Dans la premiere partie theorique on discute les elements de la theorie de RMN, necessaires pour l'etude des proprietes des polymeres solides: la methode des moments, la relaxation nucleaire et la distribution des temps de correlation. La deuxieme partie presente les resultats des experiences. (auteur)

  12. Nuclear magnetic resonance studies at high pressures

    International Nuclear Information System (INIS)

    Jonas, J.

    1980-01-01

    Recent advances in the field of NMR spectroscopy at high pressure are reviewed. After a brief discussion of two novel experimental techniques, the main focus of this review is on several specific studies which illustrate the versatility and power of this high pressure field. Experimental aspects of NMR measurements at high pressure and high temperature and the techniques for the high resolution NMR spectroscopy at high pressure are discussed. An overview of NMR studies of the dynamic structure of simple polyatomic liquids and hydrogen bonded liquids is followed by a discussion of high resolution spectroscopy at high pressure. Examples of NMR studies of disordered organic solids and polymers conclude the review. (author)

  13. A functional magnetic resonance imaging study

    Indian Academy of Sciences (India)

    MADU

    systems and ultra fast imaging techniques, such as echo planar imaging (EPI ) ... is used to understand brain organization, assessing of neurological status, and ..... J C 1998 Functional MRI studies of motor recovery after stroke;. NeuroImage 7 ...

  14. Studies on inclusive meson resonance and particle production

    International Nuclear Information System (INIS)

    Saarikko, Heimo

    1978-01-01

    Production and decay of meson resonances are studied in medium energy meson-proton collisions. Strong evidence is found that hadronic collisions are dominated by resonance production. Especially the vector mesons have often large inclusive cross sections, typically of the order of few millibarns at the present energies. In all, a majority of pions and kaons appear to be decay products of resonances or other unstable particles. The detailed kinematics of the parent resonance's decays is found to play an important role in determining inclusive pion spectra. The squared transverse momentum distributions of hadrons heavier than the pion appear to have in common an exponential behaviour, with a universal slope for the esponential fall-off. The observed vector meson yields suggest that only a small fraction of the direct lepton production observed at large transverse momentum in nucleon-nucleon interactions is accounted for by the ''old'' vector mesons. An attempt has been made to separate out the central production and fragmentation components of the meson production. Both the central production and the fragmentation of the incoming meson are found to be important mechanisms in the non-strange meson production whereas the central production of strange meson resonances is rare at our energies. The ratios of the observed meson yields are found to be generally in good agreement with a simple quark-counting model. (author)

  15. Study of isovector resonances with pion charge exchange

    International Nuclear Information System (INIS)

    Baer, H.W.; Bolton, R.; Bowman, J.D.

    1982-01-01

    Studies with the pion charge exchange reactions (π/sup +-/,π 0 ) at 164 MeV using the LAMPF π 0 spectrometer are yielding new results on the existence and systematic features of isovector resonances in nuclei. These experiments possess an unusually high signal/background ratio for isovector resonances of low-multipolarity. Results obtained to date are: (1) observation and angular disribution measurement of the giant dipole resonance in nuclei 12 C, 40 Ca, 90 Zr, and 120 Sn; and (2) observation and angular distribution measurements in the (π - ,π 0 ) reaction on 90 Zr and 120 Sn of large signals possessing the expected angular distribution shapes and magnitudes for the isovector monopole resonance. Excitation energies are near the hydrodynamical model values 170 A - /sup 1/3/ MeV. Differential cross sections are approximately 0.7 J 1 2 (qR) mb/sr. An overview of this experimental program, with emphasis on new results and how they correlate with existing knowledge on the isovector resonances, is presented

  16. Resonance magnetic x-ray scattering study of erbium

    DEFF Research Database (Denmark)

    Sanyal, M.K.; Gibbs, D.; Bohr, J.

    1994-01-01

    The magnetic phases of erbium have been studied by resonance x-ray-scattering techniques. When the incident x-ray energy is tuned near the L(III) absorption edge, large resonant enhancements of the magnetic scattering are observed above 18 K. We have measured the energy and polarization dependence...... of this magnetic scattering and analyzed it using a simple model based on electric dipole and quadrupole transitions among atomic orbitals. The line shapes can be fitted to a magnetic structure combining both c-axis-modulated and basal-plane components. Below 18 K, we have observed unusual behavior of the magnetic...

  17. Resonant inelastic x-ray scattering studies of elementary excitations

    NARCIS (Netherlands)

    Ament, Lucas Johannes Peter (Luuk)

    2010-01-01

    Resonant Inelastic X-ray Scattering (RIXS) is an X-ray in, X-ray out technique that enables one to study the dispersion of excitations in solids. In this thesis, we investigated how various elementary excitations of transition metal oxides show up in RIXS spectra.

  18. Resonance Raman study on distorted symmetry of porphyrin in ...

    Indian Academy of Sciences (India)

    The resonance Raman (RR) spectra of nickel octaethyl porphyrin, Ni(OEP), ... Nickel ocatethyl porphyrin, Ni(OEP), plays a central role in studies of the molec- ..... [8] T Kitagawa and Y Ozaki, Structure and bonding (Springer-Verlag, Berlin, ... [10] R S Czernuszewicz, K A Macar, Li Xiao-Yuan, J R Kincaid and T G Spiro, J. Am.

  19. Non-resonant microwave absorption studies of superconducting ...

    Indian Academy of Sciences (India)

    Abstract. Non-resonant microwave absorption (NRMA) studies of superconducting MgB2 and a sample containing 10% by weight of MgO in MgB2 are reported. The NRMA results indicate near absence of intergranular weak links in the pure MgB2 sample. A linear temperature dependence of the lower critical field Hc1 is ...

  20. Optical and magnetic resonance measurements of a segmented poly(ester urethane)

    International Nuclear Information System (INIS)

    Cooke, D.W.; Muenchausen, R.E.; Bennett, B.L.; Orler, E.B.; Wrobleski, D.A.; Smith, M.E.; Jahan, M.S.; Thomas, D.E.

    1999-01-01

    X-ray-induced damage in Estane(registered trademark)5703 has been studied by luminescence, optical absorption and electron spin resonance techniques in the temperature interval ∼10-300 K. Molecular motion of the polymer soft segment, as determined by viscoelastic measurements, is correlated with features in the glow curve, indicating charge detrapping via thermal destruction of cavity traps. Spectral emission is characterized by four Lorentzian bands with maxima at 2.38, 2.55, 2.74 and 2.93 eV, which are attributed to triplet-to-singlet electronic transitions of the phenyl group in the polymer hard segment. Absorption peaks at 3.97, 4.29 and 4.46 eV are also assigned to transitions within this group. Several radicals with overlapping resonances are induced at 35 K, which, with increasing temperature, evolve into the relatively stable peroxy free-radical at room temperature

  1. Nuclear magnetic resonance studies of biological systems

    International Nuclear Information System (INIS)

    Antypas, W.G. Jr.

    1988-01-01

    The difference between intracellular and extracellular proton relaxation rates provides the basis for the determination of the mean hemoglobin concentration (MHC) in red blood cells. The observed water T 1 relaxation data from red blood cell samples under various conditions were fit to the complete equation for the time-dependent decay of magnetization for a two-compartment system including chemical exchange. The MHC for each sample was calculated from the hematocrit and the intracellular water fraction as determined by NMR. The binding of the phosphorylcholine (PC) analogue, 2-(trimethylphosphonio)-ethylphosphate (phosphoryl-phosphocholine, PPC) to the PC binding myeloma proteins TEPC-15, McPC 603, and MOPC 167 was studied by 31 P NMR

  2. Study of giant multipole resonances in 40Ca

    International Nuclear Information System (INIS)

    Rost, H.

    1979-01-01

    In the present thesis giant resonance states in 40 Ca were studied by scattering of 104 MeV a particles on 40 Ca and by the reactions 39 K(p vector,p') 39 K and 39 K(p,α) 36 Ar. The scattered α-particles were measured at extreme forward angles (THETAsub(L) = 4 0 -16 0 C), because at forward angles the cross sections for the excitation of states with spin 0 and 1 strongly differ from those with higher spin. The aim of this experiment was first of all the study of the giant resonance region in 40 Ca on the contribution to 0 + or 1 - states. Beside the known electric giant quadrupole resonances at Esub(x) approx. equal to 18.5 MeV (25% EWSR) contributions of EO-strength at Esub(x) approx. equal to 21 MeV (6% EWSR) and indications to a (isoscalar) E1-strength at Esub(x) approx. equal to 14 MeV and Esub(x) approx. equal to 16 MeV were found. At the reactions 39 K(p vector,p') 39 K and 39 K(p,α) 36 Ar in the channels (p,p 0 ),(p,p 4 ), (p,αsub(o)), and (p,α 1 ) at incident energies at about 10 MeV (Esub(x)( 40 Ca) approx. equal to 18 MeV) resonant structures were observed. A scattering phase analysis performed for the elastic proton scattering didn't however yield quantitative results about the resonance parameter. An expansion of the cross sections by Legendre polynomials for the remaining reaction channel didn't allow a conclusion about the dominance of a certain L-value. The only indication to the connection of the observed resonant structures with the giant quadrupole resonance in 40 Ca is therefore the energetic position at about Esub(x) approx. equal to 18 MeV. Altogether the observed structures however were not very pronounced, so it can be concluded, that the excitation of the giant quadrupole resonance in 40 Ca by protons via the ground state of 39 K occurs not very strongly. (orig./HSI) [de

  3. Study of inelastic proton scattering at isobaric analog resonances

    International Nuclear Information System (INIS)

    Davis, S.L.

    1974-01-01

    Inelastic proton scattering at isobaric analog resonances (IAR's) was studied using the targets 138 Ba and 92 Mo. Differential cross sections and analyzing powers were measured at the 10.00, 10.63, 11.09, 11.45, and 11.70 MeV resonances in 138 Ba + p and at the 5.89, 6.09, and 6.55 MeV resonances in 92 Mo + p. In addition, a new measurement, the spin flip asymmetry, was developed. The experiment was performed by using a polarized beam to make spin flip measurements. Angular distributions for the spin flip probability and spin flip asymmetry were measured at all of the above energies except for the lowest three resonances in 138 Ba, where only the spin flip probability was measured. A DWBA code modified to include the coherent addition of resonance amplitudes was used to analyze the 138 Ba data. The partial widths extracted from this analysis were converted to expansion coefficients for parent states in 139 Ba. The coefficients were found to be in good agreement with unified model calculations. For 92 Mo, inelastic polarizations, deduced from the spin flip and spin flip asymmetry, were found to be large. Attempts using Hauser Feshbach theory to describe both the cross section and polarization data repeatedly failed for both the 6.55 and 5.87 MeV IAR's. This failure represents strong evidence that Hauser Feshbach theory is not valid when extended to describe scattering at an IAR. The 92 Mo data were analyzed using a reaction theory modified to include channel-channel correlations. This theory predicts that the enhanced compound scattering is identical to the resonance scattering. Good fits have been obtained with the use of this modified Hauser Feshbach theory. (U.S.)

  4. Magnetic resonance study of maghemite-based magnetic fluid

    International Nuclear Information System (INIS)

    Figueiredo, L.C.; Lacava, B.M.; Skeff Neto, K.; Pelegrini, F.; Morais, P.C.

    2008-01-01

    This study reports on the magnetic resonance (MR) data (X-band experiment) of 10.2 nm average diameter maghemite nanoparticle in the temperature range of 100-230 K. Maghemite nanoparticles were suspended as low-pH ionic magnetic fluid containing 2.3x10 17 particles/cm 3 . The temperature dependence of both resonance linewidth and resonance field of the zero-field-cooled sample as well as the resonance field of the field-cooled sample (angular variation experiment) was analyzed using well-established methodology. Information regarding particle size, particle clusterization and surface magnetic anisotropy were obtained from the analysis of the MR data. The number of magnetic sites per particle from the MR data is in excellent agreement with the number provided by the transmission electron microscopy (TEM) data. The demagnetizing field value obtained from the MR data indicates cluster of particles containing on average 1.42 particles. The MR angular variation data suggest that magnetoelastic effect accounts for the non-linearity observed for the surface component of the magnetic anisotropy

  5. Nuclear magnetic resonance studies of epithelial metabolism and function

    International Nuclear Information System (INIS)

    Balaban, R.S.

    1982-01-01

    Nuclear magnetic resonance (NMR) is a noninvasive technique for studying cellular metabolism and function. In this review the general applications and advantages of NMR will be discussed with specific reference to epithelial tissues. Phosphorus NMR investigations have been performed on epithelial tissues in vivo and in vitro; however, other detectable nuclei have not been utilized to date. Several new applications of phosphorus NMR to epithelial tissues are also discussed, including studies on isolated renal tubules and sheet epithelia

  6. Effect of Noise on the Decoherence of a Central Electron Spin Coupled to an Antiferromagnetic Spin Bath

    Directory of Open Access Journals (Sweden)

    G. C. Fouokeng

    2014-01-01

    Full Text Available We analyze the influence of a two-state autocorrelated noise on the decoherence and on the tunneling Landau-Zener (LZ transitions during a two-level crossing of a central electron spin (CES coupled to a one dimensional anisotropic-antiferomagnetic spin, driven by a time-dependent global external magnetic field. The energy splitting of the coupled spin system is found through an approach that computes the noise-averaged frequency. At low magnetic field intensity, the decoherence (or entangled state of a coupled spin system is dominated by the noise intensity. The effects of the magnetic field pulse and the spin gap antiferromagnetic material used suggest to us that they may be used as tools for the direct observation of the tunneling splitting through the LZ transitions in the sudden limit. We found that the dynamical frequencies display basin-like behavior decay with time, with the birth of entanglement, while the LZ transition probability shows Gaussian shape.

  7. Nuclear resonance vibrational spectroscopic studies of iron-containing biomolecules

    International Nuclear Information System (INIS)

    Ohta, Takehiro; Seto, Makoto

    2014-01-01

    In this review, we report recent nuclear resonance vibrational spectroscopic (NRVS) studies of iron-containing biomolecules and their model complexes. The NRVS is synchrotron-based element-specific vibrational spectroscopic methods. Unlike Raman and infrared spectroscopy, the NRVS can investigate all iron motions without selection rules, which provide atomic level insights into the structure/reactivity correlation of biologically relevant iron complexes. (author)

  8. Optimization experiments on the study of giant resonance in nuclei

    International Nuclear Information System (INIS)

    Lyubarskij, G.Ya.; Savitskij, G.A.; Fartushnyj, V.A.; Khazhmuradov, M.A.; Levandovskij, S.P.

    1988-01-01

    Optimum choice of the target exposure to a beam in experiments on the study of giant resonances in nuclei is considered. Optimization is aimed at reducing mean square errors of defined formfactors. Four different optimization quality criteria - variances of four form factor experimental values are considered. Variances resulting form optimization are 1.5-2 times as less as variances in real experiment. The effect of experiment design optimization criterion on form factors determination errors is ascertained. 1 ref.; 3 tabs

  9. Study of resonances produced in Heavy Ion Collisions

    Science.gov (United States)

    Quattrocchi, L.; Acosta, L.; Auditore, L.; Cardella, G.; Chbihi, A.; De Filippo, E.; Favela, F.; Gnoffo, B.; Lanzalone, G.; Martel, I.; Martorana, N. S.; Pagano, A.; Pagano, E. V.; Papa, M.; Pirrone, S.; Politi, G.; Porto, F.; Rizzo, F.; Russotto, P.; Trifirò, A.; Trimarchi, M.; Verde, G.; Veselsky, M.

    2018-05-01

    At Laboratori Nazionali del Sud of Catania an experiment has been carried out in order to investigate the correlations between particles produced in 12C+24Mg reaction at 35 AMeV incident energy. Two α correlation has been explored because provide information about temperature of 8Be nuclei produced in the reaction, while three α correaltion has been studied in order to evaluate the competition between sequential and direct decay mode of resonances produced in 12C quasi-projectiles.

  10. A study of spinal cord tumors by magnetic resonance imaging

    Energy Technology Data Exchange (ETDEWEB)

    Gushiken, Isao; Nishihira, Takeshi; Nakasone, Tomohiro [Ryukyu Univ., Nishihara, Okinawa (Japan). School of Medicine; Takara, Hiroaki; Oshiro, Yutaka; Oshiro, Takashi; Isa, Makoto; Kinjo, Yukio; Ibaraki, Kunio

    1989-10-01

    We studied 17 cases of spinal cord tumors using magnetic resonance imaging. According to the intensity of image and histological feature of spinal cord tumors, we identified two groups in T2 weighted imaging. One was a hypointensity group showing cystic or vascular tumors, and the other was hyperintensity group of solid tumors. Preoperative images of swelling, narrowing, deviation of the spinal cord were remained after the operations. Grafted free fatty tissue for the prevention of adhesion was recognized well also after the operation. Postoperative imagings sometime showed pseudo-deviation of the spinal cord which was easy to be mistaken as the remains of tumors and narrowing of the spinal cord. In conclusion, the magnetic resonance imaging makes very early detection of spinal cord tumors possible, and it is valuable for a diagnosis of the spinal cord tumor associated with brain tumor. (author).

  11. A study of spinal cord tumors by magnetic resonance imaging

    International Nuclear Information System (INIS)

    Gushiken, Isao; Nishihira, Takeshi; Nakasone, Tomohiro; Takara, Hiroaki; Oshiro, Yutaka; Oshiro, Takashi; Isa, Makoto; Kinjo, Yukio; Ibaraki, Kunio.

    1989-01-01

    We studied 17 cases of spinal cord tumors using magnetic resonance imaging. According to the intensity of image and histological feature of spinal cord tumors, we identified two groups in T2 weighted imaging. One was a hypointensity group showing cystic or vascular tumors, and the other was hyperintensity group of solid tumors. Preoperative images of swelling, narrowing, deviation of the spinal cord were remained after the operations. Grafted free fatty tissue for the prevention of adhesion was recognized well also after the operation. Postoperative imagings sometime showed pseudo-deviation of the spinal cord which was easy to be mistaken as the remains of tumors and narrowing of the spinal cord. In conclusion, the magnetic resonance imaging makes very early detection of spinal cord tumors possible, and it is valuable for a diagnosis of the spinal cord tumor associated with brain tumor. (author)

  12. Torque for electron spin induced by electron permanent electric dipole moment

    Energy Technology Data Exchange (ETDEWEB)

    Senami, Masato, E-mail: senami@me.kyoto-u.ac.jp, E-mail: akitomo@scl.kyoto-u.ac.jp; Fukuda, Masahiro, E-mail: senami@me.kyoto-u.ac.jp, E-mail: akitomo@scl.kyoto-u.ac.jp; Ogiso, Yoji, E-mail: senami@me.kyoto-u.ac.jp, E-mail: akitomo@scl.kyoto-u.ac.jp; Tachibana, Akitomo, E-mail: senami@me.kyoto-u.ac.jp, E-mail: akitomo@scl.kyoto-u.ac.jp [Department of Micro Engineering, Kyoto University, Kyoto 615-8540 (Japan)

    2014-10-06

    The spin torque of the electron is studied in relation to the electric dipole moment (EDM) of the electron. The spin dynamics is known to be given by the spin torque and the zeta force in quantum field theory. The effect of the EDM on the torque of the spin brings a new term in the equation of motion of the spin. We study this effect for a solution of the Dirac equation with electromagnetic field.

  13. A study on the retrospective dosimetry using electron paramagnetic resonance spectroscopy of tooth enamel

    International Nuclear Information System (INIS)

    Hong, Dae Seok

    2004-02-01

    Retrospective dosimetry is a process that is a part of dose reconstruction for estimation of exposed dose occurred years before the estimation. Dose reconstruction may be required in a variety of situations such as acute accidental exposure, suspected chronic overexposure and reassessment of occupational exposure. The techniques for retrospective can be classified as biological method and physical method. As a distinct physical technique for dose reconstruction, EPR (Electron Paramagnetic Resonance) or ESR (Electron Spin Resonance) dosimetry has been widely used. In EPR dosimetry, electrons generated by the interaction of material with radiation and trapped in lattice are measured by microwave absorption spectroscopy. Among the materials used for EPR dosimetry, tooth enamel has a high sensitivity for ionising radiation and since the tooth follows the carrier in all situations, it can act as a lifetime-dosimeter. And it is considered as one of the important biological samples. In many countries, there have been a lot of studies and practical applications on EPR dosimetry with tooth enamel. This technique has been applied for A-bomb survivors, Techa riverside population, Chernobyl cleanup workers and so on. Also there were two times of international comparison of the results of EPR dosimetry with tooth enamel in 1996 and 2000 respectively. But the experts have yet to reach a consensus on the best method. So, a lot of methods have been used for the separation of enamel from teeth and this may influence the dose evaluation. With the factors affecting EPR spectrum, this can effect on the results of dose reconstructed. In this study, factors affecting the EPR spectrum of tooth are experimented first. Anisotropy of radiation induced CO 2 - radical is negligible at low doses, but it become important at high doses. It can induce errors in dose estimation up to 40% at dose range of 5Gy. So, crushing process is essential in dose estimation. But, since sample grinding can

  14. Electron-spin polarization in tunnel junctions with ferromagnetic EuS barriers

    International Nuclear Information System (INIS)

    Hao, X.; Moodera, J.S.; Meservey, R.

    1989-01-01

    The authors report here spin-polarized tunneling experiments using non-ferromagnetic electrodes and ferromagnetic EuS barriers. Because of the conduction band in EuS splits into spin-up and spin-down subbands when the temperature is below 16.7 K, the Curie temperature of EuS, the tunnel barrier for electrons with different spin directions is different, therefore giving rise to tunnel current polarization. The spin-filter effect, as it may be called, was observed earlier, directly or indirectly, by several groups: Esaki et al. made a tunneling study on junctions having EuS and EuSe barriers; Thompson et al. studied Schottky barrier tunneling between In and doped EuS; Muller et al. and Kisker et al. performed electron field emission experiments on EuS-coated tungsten tips. The field emission experiments gave a maximum polarization of (89 + 7)% for the emitted electrons. Although the previous tunneling studies did not directly show electron polarization, their results were explained by the same spin- filter effect. This work uses the spin-polarized tunneling technique to show directly that tunnel current is indeed polarized and polarization can be as high as 85%

  15. Electrical control of a confined electron spin in a silicene quantum dot

    Science.gov (United States)

    Szafran, Bartłomiej; Mreńca-Kolasińska, Alina; Rzeszotarski, Bartłomiej; Żebrowski, Dariusz

    2018-04-01

    We study spin control for an electron confined in a flake of silicene. We find that the lowest-energy conduction-band levels are split by the diagonal intrinsic spin-orbit coupling into Kramers doublets with a definite projection of the spin on the orbital magnetic moment. We study the spin control by AC electric fields using the nondiagonal Rashba component of the spin-orbit interactions with the time-dependent atomistic tight-binding approach. The Rashba interactions in AC electric fields produce Rabi spin-flip times of the order of a nanosecond. These times can be reduced to tens of picoseconds provided that the vertical electric field is tuned to an avoided crossing opened by the Rashba spin-orbit interaction. We demonstrate that the speedup of the spin transitions is possible due to the intervalley coupling induced by the armchair edge of the flake. The study is confronted with the results for circular quantum dots decoupled from the edge with well defined angular momentum and valley index.

  16. Electron spin transition causing structure transformations of earth's interiors under high pressure

    Science.gov (United States)

    Yamanaka, T.; Kyono, A.; Kharlamova, S.; Alp, E.; Bi, W.; Mao, H.

    2012-12-01

    To elucidate the correlation between structure transitions and spin state is one of the crucial problems for understanding the geophysical properties of earth interiors under high pressure. High-pressure studies of iron bearing spinels attract extensive attention in order to understand strong electronic correlation such as the charge transfer, electron hopping, electron high-low spin transition, Jahn-Teller distortion and charge disproponation in the lower mantle or subduction zone [1]. Experiment Structure transitions of Fe3-xSixO4, Fe3-xTixO4 Fe3-xCrxO4 spinel solid solution have been investigated at high pressure up to 60 GPa by single crystal and powder diffraction studies using synchrotron radiation with diamond anvil cell. X-ray emission experiment (XES) at high pressure proved the spin transition of Fe-Kβ from high spin (HS) to intermediate spin state (IS) or low spin state (LS). Mössbauer experiment and Raman spectra study have been also conducted for deformation analysis of Fe site and confirmation of the configuration change of Fe atoms. Jahn-Teller effect A cubic-to-tetragonal transition under pressure was induced by Jahn-Teller effect of IVFe2+ (3d6) in the tetrahedral site of Fe2TiO4 and FeCr2O4, providing the transformation from 43m (Td) to 42m (D2d). Tetragonal phase is formed by the degeneracy of e orbital of Fe2+ ion. Their c/a ratios are c/adisordered in the M2 site. At pressures above 53 GPa, Fe2TiO4 structure further transforms to Pmma. This structure change results in the order-disorder transition [2]. New structure of Fe2SiO4 The spin transition exerts an influence to Fe2SiO4 spinel structure and triggers two distinct curves of the lattice constant in the spinel phase. The reversible structure transition from cubic to pseudo-rhombohedral phase was observed at about 45 GPa. This transition is induced by the 20% shrinkage of ionic radius of VIFe2+at the low sin state. Laser heating experiment at 1500 K has confirmed the decomposition from the

  17. In utero eyeball development study by magnetic resonance imaging.

    Science.gov (United States)

    Brémond-Gignac, D S; Benali, K; Deplus, S; Cussenot, O; Ferkdadji, L; Elmaleh, M; Lassau, J P

    1997-01-01

    The aim of this study was to measure fetal ocular development and to determine a growth curve by means of measurements in utero. Fetal ocular development was recorded by analysis of the results of magnetic resonance imaging (MRI). An anatomic study allowed definition of the best contrasted MRI sequences for calculation of the ocular surface. Biometric analysis of the values of the ocular surface in the neuro-ocular plane in 35 fetuses allowed establishment of a linear model of ocular growth curve in utero. Evaluation of ocular development may allow the detection and confirmation of malformational ocular anomalies such as microphthalmia.

  18. Measurement of single electron and nuclear spin states based on optically detected magnetic resonance

    Energy Technology Data Exchange (ETDEWEB)

    Berman, Gennady P [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Bishop, Alan R [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Chernobrod, Boris M [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Hawley, Marilyn E [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Brown, Geoffrey W [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Tsifrinovich, Vladimir I [Polytechnic University, Brooklyn, NY 11201 (United States)

    2006-05-15

    A novel approach for measurement of single electron and nuclear spin states is suggested. Our approach is based on optically detected magnetic resonance in a nano-probe located at the apex of an AFM tip. The method provides single electron spin sensitivity with nano-scale spatial resolution.

  19. Measurement of single electron and nuclear spin states based on optically detected magnetic resonance

    International Nuclear Information System (INIS)

    Berman, Gennady P; Bishop, Alan R; Chernobrod, Boris M; Hawley, Marilyn E; Brown, Geoffrey W; Tsifrinovich, Vladimir I

    2006-01-01

    A novel approach for measurement of single electron and nuclear spin states is suggested. Our approach is based on optically detected magnetic resonance in a nano-probe located at the apex of an AFM tip. The method provides single electron spin sensitivity with nano-scale spatial resolution

  20. Study of the maguemite-hematite transformation by magnetic resonance

    International Nuclear Information System (INIS)

    Portella, P.D.

    1979-08-01

    The conversion of γ-Fe 2 O 3 powders to α-Fe 2 O 3 has been studied with the magnetic resonance technique. The residual fraction of γ-Fe 2 O 3 was measured for several times and temperatures of isothermal treatments, in the range 450 0 C - 550 0 C. The transformation can be described by a first order Kinetic equation and the apparent activation energy is about 200 kJ/mol (48 kcal/mol). This value is independent of temperature and particle size. The experimental data suggest that the reaction is growth-controlled and nucleation occurs preferably at the particle surface. (Author) [pt