Search results for "Magnetism"
showing 10 items of 1934 documents
Magnetic Properties Experiments on the Mars Exploration Rover Spirit at Gusev Crater
2004
The magnetic properties experiments are designed to help identify the magnetic minerals in the dust and rocks on Mars—and to determine whether liquid water was involved in the formation and alteration of these magnetic minerals. Almost all of the dust particles suspended in the martian atmosphere must contain ferrimagnetic minerals (such as maghemite or magnetite) in an amount of ∼2% by weight. The most magnetic fraction of the dust appears darker than the average dust. Magnetite was detected in the first two rocks ground by Spirit.
Combination of geo- pedo- and technogenic magnetic and geochemical signals in soil profiles - Diversification and its interpretation: A new approach.
2016
Magnetic and geochemical parameters of soils are determined with respect to geology, pedogenesis and anthropopression. Depending on local conditions these factors affect magnetic and geochemical signals simultaneously or in various configurations. We examined four type of soils (Entic Podzol, Eutric Cambisol, Humic Cambisol and Dystric Cambisol) developed on various bedrock (the Tumlin Sandstone, basaltoid, amphibolite and serpentinite, respectively). Our primary aim was to characterize the origin and diversification of the magnetic and geochemical signal in soils in order to distinguish the most reliable methods for correct interpretation of measured parameters. Presented data include sele…
Integrated stratigraphy of the Oligocene pelagic sequence in the Umbria- Marche basin (north-eastern Apennines, Italy): A potential Global Stratotype…
2008
The Oligocene represents an important time period from a wide range of perspectives and includes signifi cant climatic and eustatic variations. The pelagic succession of the Umbria-Marche Apennines (central Italy) includes a complete and continuous sequence of marly limestones and marls, with volcaniclastic layers that enable us to construct an integrated stratigraphic framework for this time period. We present here a synthesis of detailed biostratigraphic, magnetostratigraphic, and hemostratigraphic studies, along with geochronologic results from several biotite-rich volcaniclastic layers, which provide the means for an accurate and precise radiometric calibration of the Oligocene time sca…
Atmospheric Corrosion Investigation in Industrial, Marine and Rural Environments in South-East Brazil
2002
ASTM 283-C, AISI 304 and 316-L steel specimens (called coupons) were exposed in marine, industrial and rural area(s) for different periods ranging between 1–12 months, in four different season campaigns. The corrosion rate was determined by chemical loss measurements. Rust characterization was performed by XRD, SEM, optical, and Mossbauer spectroscopy (in transmission and backscattering geometry). Superparamagnetic maghemite and goethite were found as corrosion products. Magnetic goethite and feroxyhite decrease with time of exposure. Lepidochrosite is detected and its intensity increase with the atmospheric exposure time. The results obtained from XRD and Mossbauer are in good agreement.
Characterisation of the magnetic iron phases in Clovis Class rocks in Gusev crater from the MER Spirit Mössbauer spectrometer
2007
Abstract Mossbauer backscattering spectra of eight Martian rocks, acquired by the MIMOS II spectrometer of Rover Spirit (MER-A) and containing goethite in addition to other iron minerals, have been selected for in-depth numerical analysis. Where feasible, different temperature windows for a given rock were considered. A novel calibration/folding procedure, exclusively based on the fitted positions of the eight prominent absorption lines in the transmission spectra of the reference target and not relying on the error signal of the MIMOS II spectrometer, has been developed. It is demonstrated that this procedure yields reliable and reasonably accurate values for the adjusted Mossbauer paramet…
33S hyperfine interactions in H2S and SO2 and revision of the sulfur nuclear magnetic shielding scale
2014
Using the Lamb-dip technique, the hyperfine structure in the rotational spectra of H2(33)S and (33)SO2 has been resolved and the corresponding parameters--that is, the sulfur quadrupole-coupling and spin-rotation tensors--were determined. The experimental parameters are in good agreement with results from high-level coupled-cluster calculations, provided that up to quadruple excitations are considered in the cluster operator, sufficiently large basis sets are used, and vibrational corrections are accounted for. The (33)S spin-rotation tensor for H2S has been used to establish a new sulfur nuclear magnetic shielding scale, combining the paramagnetic part of the shielding as obtained from the…
Properties of HO2• radicals induced by γ-ray irradiation in silica nanoparticles
2014
Abstract We report an experimental investigation on the effects of γ -ray irradiation in several types of silica nanoparticles previously loaded with O 2 molecules. They differ in specific surface and average diameter. By electron paramagnetic resonance (EPR) measurements we observe the generation of about 10 18 HO 2 • /cm 3 interstitial radicals. These radicals are induced by reaction of interstitial O 2 molecules with radiolytic H atoms, as previously suggested for O 2 -loaded bulk a-SiO 2 samples. However, at variance with respect to bulk materials, our experimental evidences suggest a different generation process of HO 2 • radical. In fact, by a detailed study of samples exposed to D 2 …
Spin texture motion in antiferromagnetic and ferromagnetic nanowires
2017
We propose a Hamiltonian dynamics formalism for the current and magnetic field driven dynamics of ferromagnetic and antiferromagnetic domain walls in one dimensional systems. To demonstrate the power of this formalism, we derive Hamilton equations of motion via Poisson brackets based on the Landau-Lifshitz-Gilbert phenomenology, and add dissipative dynamics via the evolution of the energy. We use this approach to study current induced domain wall motion and compute the drift velocity. For the antiferromagnetic case, we show that a nonzero magnetic moment is induced in the domain wall, which indicates that an additional application of a magnetic field would influence the antiferromagnetic do…
Stroboscopic detection of nuclear resonance in an arbitrary scattering channel
2015
The theory of heterodyne/stroboscopic detection of nuclear resonance scattering is developed, starting from the total scattering matrix as a product of the matrix of the reference sample and the sample under study. This general approach holds for any dynamical scattering channel. The forward channel, which is discussed in detail in the literature, reveals the speciality that electronic scattering causes only an energy independent diminution of the intensity. For all other channels, complex resonance line shapes in the heterodyne/stroboscopic spectra - as a result of interference of electronic and nuclear scattering - is encountered. The grazing incidence case is evaluated and described in d…
Ricci-Based Gravity theories and their impact on Maxwell and nonlinear electromagnetic models
2019
Abstract We extend the correspondence between metric-affine Ricci-Based Gravity the- ories and General Relativity (GR) to the case in which the matter sector is represented by linear and nonlinear electromagnetic fields. This complements previous studies focused on fluids and scalar fields. We establish the general algorithm that relates the matter fields in the GR and RBG frames and consider some applications. In particular, we find that the so-called Eddington-inspired Born-Infeld gravity theory coupled to Maxwell electromag- netism is in direct correspondence with GR coupled to Born-Infeld electromagnetism. We comment on the potential phenomenological implications of this relation.