EPR (Electron Paramagnetic Resonance) Spectroscopy of Polycrystalline Oxide Systems

Murphy, D. M.

doi:10.1002/9783527626113.ch1

Cited by 23 publications

(28 citation statements)

References 53 publications

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“…In this section, we present a theoretical analysis of inhomogeneous broadening of hyperfine transitions of 2 S atoms embedded in an inert matrix. The theory is based on the hyperfine Hamiltonian commonly used to calculate powder ESR spectra [45][46][47], which we extend to the lowfield limit of interest to the matrix isolation experiments described here. The primary focus will be on alkali-metal atoms trapped in solid p-H 2 , although our theory is sufficiently general to be applicable to any S-state atom in an inert matrix.…”

Section: A Inhomogeneous Broadening Due To Hyperfine Interactionsmentioning

confidence: 99%

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Spin coherence and optical properties of alkali-metal atoms in solid parahydrogen

et al. 2019

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We present a joint experimental and theoretical study of spin coherence properties of 39 K, 85 Rb, 87 Rb, and 133 Cs atoms trapped in a solid parahydrogen matrix. We use optical pumping to prepare the spin states of the implanted atoms and circular dichroism to measure their spin states. Optical pumping signals show order-of-magnitude differences depending on both matrix growth conditions and atomic species. We measure the ensemble transverse relaxation times (T * 2 ) of the spin states of the alkali-metal atoms. Different alkali species exhibit dramatically different T * 2 times, ranging from sub-microsecond coherence times for high mF states of 87 Rb, to ∼ 10 2 microseconds for 39 K. These are the longest ensemble T * 2 times reported for an electron spin system at high densities (n 10 16 cm −3 ). To interpret these observations, we develop a theory of inhomogenous broadening of hyperfine transitions of 2 S atoms in weakly-interacting solid matrices. Our calculated ensemble transverse relaxation times agree well with experiment, and suggest ways to longer coherence times in future work. arXiv:1910.05430v1 [physics.atom-ph]

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Section: A Inhomogeneous Broadening Due To Hyperfine Interactionsmentioning

confidence: 99%

“…We begin with the ESR Hamiltonian for a central S = 1/2 atom embedded in a solid p-H 2 host matrix [45,46,48], as illustrated in Fig. 15(a)…”

Section: A Inhomogeneous Broadening Due To Hyperfine Interactionsmentioning

confidence: 99%

Spin coherence and optical properties of alkali-metal atoms in solid parahydrogen

et al. 2019

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“…The single line broad EPR spectra for these prepared NiO particles were analyzed using Lorentzian distribution function and the EPR parameters such asvalue, peak to peak line width (Δ pp ), resonance field ( ), and spin-spin relaxation time constant ( 2 ) were calculated and listed in Table 1. The values of factor, the most important parameter for the description of the spin system, were calculated using the following equation [31,32]:…”

Section: Electron Paramagneticmentioning

confidence: 99%

Synthesis, Characterization, and Magnetic Properties of Pure and EDTA-Capped NiO Nanosized Particles

Rahal

Awad

Abdel‐Gaber

et al. 2017

Journal of Nanomaterials

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The effect of ethylenediaminetetraacetic acid (EDTA) as a capping agent on the structure, morphology, optical, and magnetic properties of nickel oxide (NiO) nanosized particles, synthesized by coprecipitation method, was investigated. Nickel chloride hexahydrate and sodium hydroxide (NaOH) were used as precursors. The resultant nanoparticles were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). XRD patterns showed that NiO have a face-centered cubic (FCC) structure. The crystallite size, estimated by Scherrer formula, has been found in the range of 28–33 nm. It is noticed that EDTA-capped NiO nanoparticles have a smaller size than pure nanoparticles. Thus, the addition of 0.1 M capping agent EDTA can form a nucleation point for nanoparticles growth. The optical and magnetic properties were investigated by Fourier transform infrared spectroscopy (FTIR) and UV-vis absorption spectroscopy (UV) as well as electron paramagnetic resonance (EPR) and magnetization measurements. FTIR spectra indicated the presence of absorption bands in the range of 402–425 cm−1, which is a common feature of NiO. EPR for NiO nanosized particles was measured at room temperature. An EPR line withgfactor ≈1.9–2 is detected for NiO nanoparticles, corresponding to Ni2+ions. The magnetic hysteresis of NiO nanoparticles showed that EDTA capping recovers the surface magnetization of the nanoparticles.

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“…While the hyperfine coupling observed in the EPR spectrum of 6 confirms the presence of a [Mn 2 ] unit in the resulting crystalline material, it is difficult to ascertain the amount of material that is responsible for the signatures attributed to that unit. 26 …”

Section: Resultsmentioning

confidence: 99%

Synthesis of Open-Shell, Bimetallic Mn/Fe Trinuclear Clusters

Powers

Fout

et al. 2013

J. Am. Chem. Soc.

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Concomitant deprotonation and metallation of hexadentate ligand platform tbsLH6 (tbsLH6 = 1,3,5-C6H9(NHC6H4-o-NHSiMe2 tBu)3) with divalent transition metal starting materials Fe2(Mes)4 (Mes = mesityl) or Mn3(Mes)6 in the presence of tetrahydrofuran (THF) resulted in isolation of homotrinuclear complexes (tbsL)Fe3(THF) and (tbsL)Mn3(THF) respectively. In the absence of coordinating solvent (THF) the deprotonation and metallation exclusively afforded dinuclear complexes of the type (tbsLH2)M2 (M = Fe or Mn). The resulting dinuclear species were utilized as synthons to prepare bimetallic trinuclear clusters. Treatment of (tbsLH2)Fe2 complex with divalent Mn source (Mn2(N(SiMe3)2)4) afforded the bimetallic complex (tbsL)Fe2Mn(THF) which established the ability of hexamine ligand tbsLH6 to support mixed metal clusters. The substitutional homogeneity of (tbsL)Fe2Mn(THF) was determined by 1H NMR, 57Fe Mössbauer, and X-ray fluorescence. Anomalous scattering measurements were critical for the unambiguous assignment of the trinuclear core composition. Heating a solution of (tbsLH2)Mn2 with a stoichiometric amount of Fe2(Mes)4 (0.5 mol equiv) affords a mixture of both (tbsL)Mn2Fe(THF) and (tbsL)Fe2Mn(THF) as a result of the thermodynamic preference for heavier metal substitution within the hexa-anilido ligand framework. These results demonstrate for the first time the assembly of mixed metal cluster synthesis in an unbiased ligand platform.

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EPR (Electron Paramagnetic Resonance) Spectroscopy of Polycrystalline Oxide Systems

Cited by 23 publications

References 53 publications

Spin coherence and optical properties of alkali-metal atoms in solid parahydrogen

Spin coherence and optical properties of alkali-metal atoms in solid parahydrogen

Synthesis, Characterization, and Magnetic Properties of Pure and EDTA-Capped NiO Nanosized Particles

Synthesis of Open-Shell, Bimetallic Mn/Fe Trinuclear Clusters

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