Horacio Farach

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Horacio A. Farach is an Argentine physicist.

Farach earned his masters degree and doctorate at the University of Buenos Aires, and taught at his alma mater between 1965 and 1967, before joining the University of South Carolina faculty. He retired from USC in 2004 and was granted emeritus status. [1] [2] In 1977, he was elected a fellow the American Physical Society. [3]

Selected publications

Related Research Articles

<span class="mw-page-title-main">Gadolinium</span> Chemical element, symbol Gd and atomic number 64

Gadolinium is a chemical element with the symbol Gd and atomic number 64. Gadolinium is a silvery-white metal when oxidation is removed. It is a malleable and ductile rare-earth element. Gadolinium reacts with atmospheric oxygen or moisture slowly to form a black coating. Gadolinium below its Curie point of 20 °C (68 °F) is ferromagnetic, with an attraction to a magnetic field higher than that of nickel. Above this temperature it is the most paramagnetic element. It is found in nature only in an oxidized form. When separated, it usually has impurities of the other rare-earths because of their similar chemical properties.

<span class="mw-page-title-main">Magnetic resonance imaging</span> Medical imaging technique

Magnetic resonance imaging (MRI) is a medical imaging technique used in radiology to form pictures of the anatomy and the physiological processes of the body. MRI scanners use strong magnetic fields, magnetic field gradients, and radio waves to generate images of the organs in the body. MRI does not involve X-rays or the use of ionizing radiation, which distinguishes it from computed tomography (CT) and positron emission tomography (PET) scans. MRI is a medical application of nuclear magnetic resonance (NMR) which can also be used for imaging in other NMR applications, such as NMR spectroscopy.

Unconventional superconductors are materials that display superconductivity which does not conform to conventional BCS theory or its extensions.

Spintronics, also known as spin electronics, is the study of the intrinsic spin of the electron and its associated magnetic moment, in addition to its fundamental electronic charge, in solid-state devices. The field of spintronics concerns spin-charge coupling in metallic systems; the analogous effects in insulators fall into the field of multiferroics.

In nuclear magnetic resonance (NMR) spectroscopy, the chemical shift is the resonant frequency of an atomic nucleus relative to a standard in a magnetic field. Often the position and number of chemical shifts are diagnostic of the structure of a molecule. Chemical shifts are also used to describe signals in other forms of spectroscopy such as photoemission spectroscopy.

The term "Woodstock of physics" is often used by physicists to refer to the marathon session of the American Physical Society’s meeting on March 18, 1987, which featured 51 presentations of recent discoveries in the science of high-temperature superconductors. Various presenters anticipated that these new materials would soon result in revolutionary technological applications, but in the three subsequent decades, this proved to be overly optimistic. The name is a reference to the 1969 Woodstock Music and Art Festival.

Microwave spectroscopy is the spectroscopy method that employs microwaves, i.e. electromagnetic radiation at GHz frequencies, for the study of matter.

<span class="mw-page-title-main">Gadolinium(III) chloride</span> Chemical compound

Gadolinium(III) chloride, also known as gadolinium trichloride, is GdCl3. It is a colorless, hygroscopic, water-soluble solid. The hexahydrate GdCl3∙6H2O is commonly encountered and is sometimes also called gadolinium trichloride. Gd3+ species are of special interest because the ion has the maximum number of unpaired spins possible, at least for known elements. With seven valence electrons and seven available f-orbitals, all seven electrons are unpaired and symmetrically arranged around the metal. The high magnetism and high symmetry combine to make Gd3+ a useful component in NMR spectroscopy and MRI.

<span class="mw-page-title-main">Yttrium iron garnet</span> Synthetic garnet

Yttrium iron garnet (YIG) is a kind of synthetic garnet, with chemical composition Y3Fe2(FeO4)3, or Y3Fe5O12. It is a ferrimagnetic material with a Curie temperature of 560 K. YIG may also be known as yttrium ferrite garnet, or as iron yttrium oxide or yttrium iron oxide, the latter two names usually associated with powdered forms.

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In magnetic resonance, a spin echo or Hahn echo is the refocusing of spin magnetisation by a pulse of resonant electromagnetic radiation. Modern nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) make use of this effect.

Low field NMR spans a range of different nuclear magnetic resonance (NMR) modalities, going from NMR conducted in permanent magnets, supporting magnetic fields of a few tesla (T), all the way down to zero field NMR, where the Earth's field is carefully shielded such that magnetic fields of nanotesla (nT) are achieved where nuclear spin precession is close to zero. In a broad sense, Low-field NMR is the branch of NMR that is not conducted in superconducting high-field magnets. Low field NMR also includes Earth's field NMR where simply the Earth's magnetic field is exploited to cause nuclear spin-precession which is detected. With magnetic fields on the order of μT and below magnetometers such as SQUIDs or atomic magnetometers are used as detectors. "Normal" high field NMR relies on the detection of spin-precession with inductive detection with a simple coil. However, this detection modality becomes less sensitive as the magnetic field and the associated frequencies decrease. Hence the push toward alternative detection methods at very low fields.

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<span class="mw-page-title-main">Nuclear magnetic resonance</span> Spectroscopic technique based on change of nuclear spin state

Nuclear magnetic resonance (NMR) is a physical phenomenon in which nuclei in a strong constant magnetic field are perturbed by a weak oscillating magnetic field and respond by producing an electromagnetic signal with a frequency characteristic of the magnetic field at the nucleus. This process occurs near resonance, when the oscillation frequency matches the intrinsic frequency of the nuclei, which depends on the strength of the static magnetic field, the chemical environment, and the magnetic properties of the isotope involved; in practical applications with static magnetic fields up to ca. 20 tesla, the frequency is similar to VHF and UHF television broadcasts (60–1000 MHz). NMR results from specific magnetic properties of certain atomic nuclei. Nuclear magnetic resonance spectroscopy is widely used to determine the structure of organic molecules in solution and study molecular physics and crystals as well as non-crystalline materials. NMR is also routinely used in advanced medical imaging techniques, such as in magnetic resonance imaging (MRI).

Electron nuclear double resonance (ENDOR) is a magnetic resonance technique for elucidating the molecular and electronic structure of paramagnetic species. The technique was first introduced to resolve interactions in electron paramagnetic resonance (EPR) spectra. It is currently practiced in a variety of modalities, mainly in the areas of biophysics and heterogeneous catalysis.

<span class="mw-page-title-main">Physics of magnetic resonance imaging</span> Overview article

The physics of magnetic resonance imaging (MRI) concerns fundamental physical considerations of MRI techniques and technological aspects of MRI devices. MRI is a medical imaging technique mostly used in radiology and nuclear medicine in order to investigate the anatomy and physiology of the body, and to detect pathologies including tumors, inflammation, neurological conditions such as stroke, disorders of muscles and joints, and abnormalities in the heart and blood vessels among others. Contrast agents may be injected intravenously or into a joint to enhance the image and facilitate diagnosis. Unlike CT and X-ray, MRI uses no ionizing radiation and is, therefore, a safe procedure suitable for diagnosis in children and repeated runs. Patients with specific non-ferromagnetic metal implants, cochlear implants, and cardiac pacemakers nowadays may also have an MRI in spite of effects of the strong magnetic fields. This does not apply on older devices, and details for medical professionals are provided by the device's manufacturer.

Rotational correlation time is the average time it takes for a molecule to rotate one radian. In solution, rotational correlation times are in the order of picoseconds. For example, the 1.7 ps for water, and 100 ps for a pyrroline nitroxyl radical in a DMSO-water mixture. Rotational correlation times are employed in the measurement of microviscosity and in protein characterization.

<span class="mw-page-title-main">Paramagnetic nuclear magnetic resonance spectroscopy</span> Spectroscopy of paramagnetic compounds via NMR

Paramagnetic nuclear magnetic resonance spectroscopy refers to nuclear magnetic resonance (NMR) spectroscopy of paramagnetic compounds. Although most NMR measurements are conducted on diamagnetic compounds, paramagnetic samples are also amenable to analysis and give rise to special effects indicated by a wide chemical shift range and broadened signals. Paramagnetism diminishes the resolution of an NMR spectrum to the extent that coupling is rarely resolved. Nonetheless spectra of paramagnetic compounds provide insight into the bonding and structure of the sample. For example, the broadening of signals is compensated in part by the wide chemical shift range (often 200 ppm in 1H NMR). Since paramagnetism leads to shorter relaxation times (T1), the rate of spectral acquisition can be high.

<span class="mw-page-title-main">Alfred G. Redfield</span> American molecular biologist, physicist

Alfred G. Redfield was an American physicist and biochemist. In 1955 he published the Redfield relaxation theory, effectively moving the practice of NMR or Nuclear magnetic resonance from the realm of classical physics to the realm of semiclassical physics. He continued to find novel magnetic resonance applications to solve real-world problems throughout his life.

Caesium sesquioxide is a chemical compound with the formula Cs2O3 or Cs4O6. In terms of oxidation states, Caesium in this compound has a nominal charge of +1, and the oxygen is a mixed peroxide and superoxide for a structural formula of (Cs+)4(O−2)2(O2−2). Compared to the other caesium oxides, this phase is less well studied, but has been long present in the literature. It can be created by thermal decomposition of caesium superoxide at 290 °C.

<span class="mw-page-title-main">Europium(II) oxide</span> Chemical compound

Europium(II) oxide (EuO) is a chemical compound which is one of the oxides of europium. In addition to europium(II) oxide, there is also europium(III) oxide and the mixed valence europium(II,III) oxide.

References

  1. "HORACIO A. FARACH (CV)" (PDF). University of South Carolina. Retrieved 12 July 2023.
  2. "HORACIO A. FARACH, Professor". University of South Carolina. Retrieved 12 July 2023.
  3. "APS fellow archive". American Physical Society. Retrieved 12 July 2023.
  4. Reviews of Handbook of Electron Spin Resonance include:
    • Budil, D. E. (April 1995). "Handbook of Electron Spin Resonance: Data Sources, Computer Technology, Relaxation and ENDOR, Charles P. Poole and Horacio A. Farach, Editors. AIP Press, Woodbury, New York, 1994. 660 pages. $115.00. ISBN: 1-563-96044-3". Journal of Magnetic Resonance, Series A. 113 (2): 281–282. doi:10.1006/jmra.1995.1096.
    • Kirmse, Reinhard (April 1995). "EPR-Spektroskopie: Handbook of Electron Spin Resonance - Data Sources, Computer Technology, Relaxation, and Endor. Hrsg. von C. P. Poole, Jr. und H. A. Farach. AIP Press, New York, 1994. 660 S., geb., 75,- £. ISBN 1-56396-044-3". Nachrichten aus Chemie, Technik und Laboratorium (in German). 43 (4): 460. doi:10.1002/nadc.19950430421.
  5. Gruehn, Reginald (January 1990). "Book Review: Copper Oxide Superconductors. By C. P. Poole, T. Datta and H. A. Farach". Angewandte Chemie (in German). 29 (1). doi:10.1002/anie.199001112.
  6. Weiss, Alarich (January 1974). "Charles P. Poole, Jr., and Horacio A. Farach: The Theory of Magnetic Resonance. Wiley-Interscience, New York-London-Sidney-Toronto 1972. 452 Seiten. Preis: £ 7.10". Berichte der Bunsengesellschaft für physikalische Chemie (in German). 78 (1): 100. doi:10.1002/bbpc.19740780123.