Relaxation Effects in Antiferromagnetic Ferrous Carbonate

Ok, Hang Nam

doi:10.1103/physrev.185.472

Cited by 59 publications

(19 citation statements)

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“…Note that the inferred transition temperature for the nanophase goethite component (-300 K) is greater than that observed for Manitou Springs or Obsidian Pool (see Figure 6). Figure 18 shows the variation of the magnetic hyperfine field Bhr with temperature for the Nova Scotia siderite and the siderite component of 2C3; also plotted are values for a synthetic siderite (99.5% pure FeCO3) [Ok, 1969]. It appears that the three siderites converge very nearly to the same low temperature limit for Bhf but have distinctly different magnetic transition temperatures, presumably due to different modes of production and possibly different degrees of substitution for iron in the siderite structure of the natural samples.…”

Section: Primary Precipitates ("Surface" Samples)mentioning

confidence: 99%

A Mössbauer investigation of iron‐rich terrestrial hydrothermal vent systems: Lessons for Mars exploration

Wade¹,

Agresti²,

Wdowiak³

et al. 1999

J. Geophys. Res.

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Abstract. Hydrothermal spring systems may well have been present on early Mars and could have served as a habitat for primitive life. The integrated instrument suite of the Athena Rover has, as a component on the robotic arm, a M6ssbauer spectrometer. In the context of future Mars exploration we present results of M6ssbauer analysis of a suite of samples from an iron-rich thermal spring in the Chocolate Pots area of Yellowstone National Park (YNP) and from Obsidian Pool (YNP) and Manitou Springs, Colorado. We have found that M6ss-bauer spectroscopy can discriminate among the iron-bearing minerals in our samples. Those near the vent and on the surface are identified as ferrihydrite, an amorphous ferric mineraloid. Subsurface samples, collected from cores, which are likely to have undergone inorganic and/or biologically mediated alteration (diagenesis), exhibit spectral signatures that include nontronite (a smectite clay), hematite (ot-Fe203), small-particle/nanophase goethite FeOOH), and siderite (FeCO3). We find for iron minerals that M6ssbauer spectroscopy is at least as efficient in identification as X-ray diffraction. This observation is important from an exploration standpoint. As a planetary surface instrument, M6ssbauer spectroscopy can yield high-quality spectral data without sample preparation (backscatter mode). We have also used field emission scanning electron microscopy (FESEM), in conjunction with energydispersive X ray (EDX) fluorescence spectroscopy, to characterize the microbiological component of surface sinters and the relation between the microbiological and the mineralogical framework. Evidence is presented that the minerals found in these deposits can have multibillion-year residence times and thus may have survived their possible production in a putative early Martian hot spring up to the present day. Examples include the nanophase property and the M6ssbauer signature for siderite, which has been identified in a 2.09-billion-year old hematite-rich chert stromatolite. Our research demonstrates that in situ M6ssbauer spectroscopy can help determine whether hydrothermal mineral deposits exist on Mars, which is significant for exobiology because of the issue of whether that world ever had conditions conducive to the origin of life. As a useful tool for selection of samples suitable for transport to Earth, M6ssbauer spectroscopy will not only serve geological interests but will also have potential for exopaleontology.

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Section: Primary Precipitates ("Surface" Samples)mentioning

confidence: 99%

A Mössbauer investigation of iron‐rich terrestrial hydrothermal vent systems: Lessons for Mars exploration

Wade¹,

Agresti²,

Wdowiak³

et al. 1999

J. Geophys. Res.

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“…We will give only a brief explanation. For the complete details we refer to [30,44,45]. It can be understood in terms of fluctuating hyperfine magnetic fields that exist at the sites of the nuclei.…”

Section: Level Mixing Induced Transparencymentioning

confidence: 99%

“…Due to this magnetic field, the nuclear levels of both the ground and excited states are further split (Zeeman effect) and the energy degeneracy of the states is completely lifted. The magnetic field is essentially parallel to the main axis of the electric field gradient [30]. Figure 3 The hyperfine levels of the first excited state (spin 3/2) and the ground state (spin 1/2) of 57 Fe as a function of temperature.…”

Section: Introduction To the Mössbauer Effect And The Mössbauer Spectmentioning

confidence: 98%

“…Because of the electronic structure of FeCO 3 , an electric field gradient exists at the site of the iron atoms [30], partially splitting the nuclear levels of the spin 3/2 excited state according to the absolute value of the magnetic quantum number. Below the Néel temperature of 38 K, FeCO 3 becomes antiferromagnetic and the magnetic field increases with decreasing temperature.…”

Section: Introduction To the Mössbauer Effect And The Mössbauer Spectmentioning

confidence: 99%

“…The absorber was prepared from the mineral siderite, which is FeCO 3 in which 57 Fe occurs with its natural abundance, hence nonenriched. More information on the absorber can be found in [30] and [31]. The effective thickness parameter β, a dimensionless quantity, defined by β = N 0 fσ 0 d, where N 0 is the number of resonant nuclei/cm 3 , f is the recoilfree fraction, σ 0 is the maximum cross-section evaluated on resonance, and d is the actual thickness of the sample (e.g.…”

Section: Introduction To the Mössbauer Effect And The Mössbauer Spectmentioning

confidence: 99%

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Towards more relaxed conditions for a gamma‐ray laser: Methods to realize induced transparency for nuclear resonant gamma radiation

Odeurs¹,

Hoy

Rostovtsev

et al. 2010

Laser & Photonics Reviews

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Nuclear quantum optics deals with the resonant interaction of gamma-radiation and nuclei, generally incorporated in a solid-state material. Single gamma-rays interact with an ensemble of nuclei. The properties of the resonantly forward-scattered gamma-radiation depend on the details of the interaction. An external modification of the nuclear energies will influence the interactions, and hence the properties of the radiation. Several techniques are proposed to reduce the resonant absorption of the gamma-rays, creating a nuclear medium that is partially transparent: nuclear-level-mixing induced transparency, modification of nuclear levels by means of an optical laser, phase-shift-induced transparency. Interference is crucial in all this. The partial transparency could be exploited to study special effects such as slow gamma-radiation and gain without population inversion. It could also be of importance for the realization of a gamma-ray laser.Less than expected absorption of gamma rays at nuclear level crossing (red arrow).

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A Diferrous Single‐Molecule Magnet

et al. 2007

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The diferrous complex [Fe 2 (acpypentO)(NCO) 3 ] (1), (acpypentO -= the anion of 1,5-bis[2-pyridyl(1-ethylimino)]-pentane-3-ol) was studied by spectroscopic (dual-mode Xband EPR and 57 Fe-Mössbauer) and magnetic (AC magnetic susceptibility) techniques. Complex 1 (A. K. Boudalis et al., Inorg. Chem. 2004, 43, 1574 was previously shown to exhibit an intramolecular ferromagnetic coupling with important single-ion anisotropies with marked differences in the singleion electronic parameters of the two iron sites. In this contribution, additional studies are carried out to probe its dynamic magnetic properties. Mössbauer spectra recorded at liquid helium temperatures indicate slow paramagnetic relaxation and a ground state of the system characterized by a nonKramers doublet with an Ising-type anisotropy, a condition which favours single-molecule magnet (SMM) behaviour. A

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Relaxation Effects in Antiferromagnetic Ferrous Carbonate

Cited by 59 publications

References 20 publications

A Mössbauer investigation of iron‐rich terrestrial hydrothermal vent systems: Lessons for Mars exploration

A Mössbauer investigation of iron‐rich terrestrial hydrothermal vent systems: Lessons for Mars exploration

Towards more relaxed conditions for a gamma‐ray laser: Methods to realize induced transparency for nuclear resonant gamma radiation

A Diferrous Single‐Molecule Magnet

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