scholarly journals S-band ferromagnetic resonance spectroscopy and the detection of magnetofossils

2013 ◽  
Vol 10 (80) ◽  
pp. 20120790 ◽  
Author(s):  
Andreas U. Gehring ◽  
Jessica Kind ◽  
Michalis Charilaou ◽  
Inés García-Rubio
Keyword(s):  
Ferromagnetic Resonance ◽  
Uniaxial Anisotropy ◽  
Magnetotactic Bacteria ◽  
Time Frame ◽  
Resonance Spectroscopy ◽  
Verwey Transition ◽  
Geological Time ◽  
Change Of Direction ◽  
X Band ◽  
Magnetite Particles

We report the use of S-band ferromagnetic resonance (FMR) spectroscopy to compare the anisotropic properties of magnetite particles in chains of cultured intact magnetotactic bacteria (MTB) between 300 and 15 K with those of sediment samples of Holocene age in order to infer the presence of magnetofossils and their preservation in a geological time frame. The spectrum of intact MTB at 300 K exhibits distinct uniaxial anisotropy because of the chain alignment of the cellular magnetite particles and their easy axes. This anisotropy becomes less pronounced upon cooling and below the Verwey transition ( T V ) it is nearly vanished mainly owing to the change of direction of the easy axes. In a natural sample, magnetofossils were detected by uniaxial anisotropy traits similar to those obtained from cultured MTB above T V . Our comparative study emphasizes that indispensable information can be obtained from S-band FMR spectra, which offers even a better resolution than X-band FMR for discovering magnetofossils, and this in turn can contribute towards strengthening our relatively sparse database for deciphering the microbial ecology during the Earth's history.

scholarly journals Magnetosome Organization in Magnetotactic Bacteria Unraveled by Ferromagnetic Resonance Spectroscopy

2017 ◽  
Vol 113 (3) ◽  
pp. 637-644 ◽  
Author(s):  
Sara Ghaisari ◽  
Michael Winklhofer ◽  
Peter Strauch ◽  
Stefan Klumpp ◽  
Damien Faivre
Keyword(s):  
Ferromagnetic Resonance ◽  
Magnetotactic Bacteria ◽  
Resonance Spectroscopy

Control of the morphology and size of magnetite particles with peptides mimicking the Mms6 protein from magnetotactic bacteria

2010 ◽  
Vol 343 (1) ◽  
pp. 65-70 ◽  
Author(s):  
Atsushi Arakaki ◽  
Fukashi Masuda ◽  
Yosuke Amemiya ◽  
Tsuyoshi Tanaka ◽  
Tadashi Matsunaga
Keyword(s):  
Magnetotactic Bacteria ◽  
Magnetite Particles

Broadband ferromagnetic resonance spectroscopy of permalloy triangular nanorings

2012 ◽  
Vol 100 (6) ◽  
pp. 062401 ◽  
Author(s):  
J. Ding ◽  
M. Kostylev ◽  
A. O. Adeyeye
Keyword(s):  
Ferromagnetic Resonance ◽  
Resonance Spectroscopy

scholarly journals Ferromagnetic Resonance Spectroscopy and Rock Magnetic Characterization of Fossil Coral Skeletons in Ishigaki Islands, Japan

Geosciences ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 400
Author(s):  
Yuho Kumagai ◽  
Norihiro Nakamura ◽  
Tetsuro Sato ◽  
Toshitaka Oka ◽  
Hirokuni Oda
Keyword(s):  
Ferromagnetic Resonance ◽  
Single Domain ◽  
Coral Skeleton ◽  
Resonance Spectroscopy ◽  
Continuous Growth ◽  
Coral Skeletons ◽  
Ishigaki Island ◽  
Biogenic Magnetite ◽  
A Chain ◽  
Fossil Coral

Skeletons of hermatypic corals (e.g., Porites) might have enormous potential as a high-resolution paleomagnetic recorder owing to their rapid and continuous growth over hundreds of years at a rate of up to 2 cm/year, although typical corals show an extremely weak intensity of remanence and low stability. We found that coral tsunami boulders with negligible amounts of calcite on Ishigaki Island show a measurable intensity of remanence; thus, we attempted to characterize the magnetic assemblages in this coral skeleton to determine whether it is of biogenic or detrital magnetite using first-order reversal curve (FORC) measurements, ferromagnetic resonance (FMR) spectroscopy, and petrological observations through field-emission type scanning electron microscope (FE-SEM) with an acid treatment. The FMR derivative spectra of coral skeleton samples represent multiple derivative maxima and extended low-field absorption, indicating the presence of intact biogenic magnetite chains. FORC diagrams represent a “central ridge” signature with a vertical spread. These FMR and FORC features indicate the magnetization of these coral skeletons that are mainly created using intact biogenic magnetites and mixtures of grains from collapsed biogenic magnetites, pseudo-single domain grains, and multi-domain grains such as detrital magnetite. FE-SEM observations confirm the presence of a chain-like structure of iron oxides corresponding to the features of biogenic magnetite. Therefore, the magnetic mineral assemblage in coralline boulders from Ishigaki Island consists of dominant biogenic-origin single-domain magnetite and a trace amount of detrital component, indicating that fossil coral skeletons in Ishigaki Island have potential for utilization in paleomagnetic studies.

The paramagnetic germanium–sodium impurity centres and in α-quartz

1991 ◽  
Vol 69 (7) ◽  
pp. 761-779 ◽  
Author(s):  
R. S. Dickson ◽  
J. A Weil ◽  
P. H. Davis
Keyword(s):  
Bond Angle ◽  
Resonance Spectroscopy ◽  
Crystallographic Axis ◽  
Paramagnetic Resonance ◽  
Angle Bisector ◽  
X Band ◽  
Ca 50 ◽  
X Irradiation ◽  
Na Ions ◽  
Sodium Impurity

Centres [Formula: see text] formed in α-quartz by 77 K x irradiation and warming above ca. 165 K, both exhibit a reversible change in symmetry of the centres from C1 at 75 K to C2 at 295 K, as observed by X-band electronic paramagnetic resonance spectroscopy. Each centre contains a Ge3+ ion (S = 1/2) substituted for a Si4+ ion, with a nearby Na+ interstitial ion. Spin-Hamiltonian electronic Zeeman, 73Ge and 23Na nuclear hyperfine and quadrupole parameter matrices for these centres were measured at temperatures 75, 190, and 295 K. They show that the change is associated with the defect reorienting between sites related by a two-fold crystallographic axis a, with energy barrier 0.223(6) eV for A and 0.178(14) eV for C. In both centres, ca. 50% of the spin density is located in a Ge sp orbital; in A, the sp orbital is oriented close to a, while in C it is nearly parallel to an O–Si–O bond-angle bisector that is nearly normal to a. Theoretical hyperfine matrices indicate that the Na ions are located near a, in a c-axis channel near the Ge site. Above ca. 270 K, A and C are observably in equilibrium, and are thus deemed to be isomeric species.

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