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Topic: Single-molecule


    Note: these results are not from the primary (high quality) database.


In the News (Thu 18 Jul 19)

  
 Magnet - Wikipedia, the free encyclopedia
Within each atom and molecule, the spin of each of these particles is highly ordered as a result of the Pauli Exclusion Principle.
The end of a magnet that points toward the Earth's geographic North Pole is labeled as the north pole of the magnet; correspondingly, the end that points south is the south pole of the magnet.
Magnets are also used in other types of fastening devices, such as the magnetic base, the magnetic clamp and the refrigerator magnet.
en.wikipedia.org /wiki/Magnet   (2615 words)

  
 Single-molecule magnet - Wikipedia, the free encyclopedia
A single-molecule magnet is an object that is composed of molecules each of which behaves as a magnet.
The term single-molecule magnet was coined in 1996 by George Christou, a chemist at Indiana University J. Am.
Many researchers are making efforts to raise the critical temperature of single-molecule magnets and to make compounds which show single-molecule magnet behavior at room temperature.
en.wikipedia.org /wiki/Single-molecule_magnet   (343 words)

  
 Molecular electronics - Wikipedia, the free encyclopedia
Among the important issues is the determination of the resistance of a single molecule (both theoritical and experimental).
Study of charge transfer in molecules was advanced in the 1940s by Robert Mulliken and Albert Szent-Gyorgi in discussion of so-called "donor-acceptor" systems and developed the study of charge transfer and energy transfer in molecules.
In polymers, classical organic molecules are composed of both carbon and hydrogen (and sometimes additional compounds such as nitrogen, chlorine or sulfur).
en.wikipedia.org /wiki/Molecular_electronics   (976 words)

  
 KENT LAB HOME PAGE
The magnetic properties and magnetization dynamics of polycrystalline ultra-thin Co layers were investigated using a broadband ferromagnetic resonance (FMR) technique at room temperature.
The Co layers have a lower magnetization density than the bulk, and an interface contribution to the magnetic anisotropy normal to the film plane.
However, the critical current for magnetic excitations decreases linearly with decreasing free layer thickness, extrapolating to a finite critical current in the limit of zero thickness.
www.physics.nyu.edu /kentlab/news.html   (702 words)

  
 Single-molecule - Wikipedia, the free encyclopedia
One single-molecule, an individual molecule that can be isolated or distinguished for propose of an experiment or analysis.
In opposition to an ensemble or bulk of molecules, where the individual behaviour can not be distinguished, and only average characteristics can be measured.
This page was last modified 22:55, 28 September 2005.
en.wikipedia.org /wiki/Single-molecule   (78 words)

  
 Quantum tunnelling of the magnetisation in molecular nanomagnets
An ensemble of molecules will show initially a net magnetisation pointing toward +Z but at the equilibrium half of the molecules must be pointing their spin toward B. As the X direction is the less favourite one the spin will tend to rotate in a plane which is parallel to the YZ plane.
The reversal of the magnetic moment of a molecule inside the crystal modifies the dipolar field of the neighbouring sites and other molecules are thus brought close to the resonance condition where the fluctuating hyperfine field can be efficient again in promoting tunnelling.
Thus nanosized magnetic particles, comprising hundreds or thousands of coupled spins, are good candidate to show quantum tunnelling of the magnetisation (QTM), and even better are antiferromagnetic particles, where the magnetic moment is reduced to the uncompensated fraction on the surface.
www.europhysicsnews.com /full/20/article1/article1.html   (3730 words)

  
 Magnetic Resonance Imagin... - The Experiments of I. I. ...
They discovered a series of resonances within a single molecule that allowed them to "see" how individual atoms are bound together and how their nuclei are affected by neighboring atoms.
to study the magnetic properties of atoms and molecules.
With the appropriate stimulus, he predicted, the magnetic moments of the nuclei could be induced to flip, or change their orientation relative to the magnetic field.
www.beyonddiscovery.org /content/view.asp?I=131   (772 words)

  
 Mn84: a giant single-molecule magnet
SMMs have various potential applications, including very high density information storage with each bit stored as the magnetization orientation of an individual molecule, and as quantum bits for quantum computing,[8] taking advantage of the quantum superposition of states provided by the QTM.
[17] SMMs, it is due to a broadening and smearing of the steps from a distribution of molecular environments (and thus a distribution of relaxation barriers) caused by disordered lattice solvent molecules and ligand disorder; the magnetic properties of SMMs are sensitive to such relatively small variations in local environments.
26] The Mn molecule is a 4.2 nm diameter particle.
lab-neel.grenoble.cnrs.fr /themes/nano/mn84   (2412 words)

  
 Molecular magnets for quantum devices of the future
Each magnet influences its neighbor; therefore, the quantum behavior of the single-molecule magnet dimer is different from that of the individual single-molecule magnet.
Each molecule, whose behavior may be compared to that of a compass, can be blocked in a given direction by a magnetic field, below its “blocking temperature.” Such stability guarantees that the information provided by the magnetic field will be stored and can be retrieved at a later time.
At the molecular scale, however, a purely quantum phenomenon, the "tunnel effect," can alter the magnetization of molecules.
www.cnrs.fr /cw/en/pres/compress/aimantsMolecul.htm   (417 words)

  
 PHYS
In vitro and in vivo single molecule imaging and spectroscopy.
Single molecule fluorescence resonance energy transfer studies on the HIV-1 nucleocapsid protein catalyzed annealing of transactivation response region DNA and RNA hairpins.
Single molecule fluorescence resonance energy transfer studies of the crucial intermediates in the reverse transcription of HIV-1.
hackberry.chem.trinity.edu /PHYS/fall2004.html   (7994 words)

  
 Research Interests of the Holmes Group
Magnetic measurements on the sixteen structurally related analogues indicated that one is a single-molecule magnet.
The cyanometalate ions used to construct the SMMs exhibit significant orbital anisotropy, an apparent requirement for SMM clusters, and this suggests that single-molecule magnetism is a general phenomenon.
Magnetic data obtained for a rectangular SMM cluster is illustrated in Figure 4.
www.chem.uky.edu /research/holmes/clusters.htm   (632 words)

  
 * News @Guelph *
Kathryn Preuss, Chemistry and Biochemistry, and her research team are looking at molecular magnetism, with the goal of turning a single molecule into a magnet.
Currently, data storage based on magnetism, such as the magnetic tape found inside audiocassettes, videocassettes and floppy disks, relies on the phenomenon of "bulk ferromagnetism" - the interactions between the hundreds or thousands of molecules - to maintain its magnetic properties.
But Preuss's proposed SMMs don't need to interact with molecules around them to stay magnetic.
www.uoguelph.ca /atguelph/03-06-18/articles/magnet.html   (335 words)

  
 ACNS Conference 2004
} is a singlet ground state single molecule magnet system with isolated clusters of 30 s=5/2 ions on the vertices of an isododecahedron.
TP50: Inelastic Neutron Scattering Studies of the Single Molecule Magnet {Fe Mo
Materials consisting of magnetic molecules are ideal prototypes for the study of fundamental problems of magnetism at the nanoscale level.
www.ncnr.nist.gov /acns/program/abstract/tp50.html   (103 words)

  
 ILL ANNUAL REPORT 2002
Single Molecule Magnets (SMM) are clusters formed by a finite number of exchange-coupled transition-metal ions [1].
H atoms, disordered solvent molecules and methyl groups are not shown for clarity.
Macroscopic SMM samples are a collection of perfectly identical and weakly interacting clusters, allowing to observe quantum-mechanical effects through macroscopic measurements [2].
www.ill.fr /AR-02/site/areport/fb_30.htm   (1062 words)

  
 Single Magnet Molecules attracting Computer Scientists
Professor George Christou from University of Florida Chemistry says that since single magnetic molecules are much smaller than even the smallest magnetic particles and they can be used to store information at a density of one bit of information per molecule.
SMMs which are nothing but transition-metal clusters differ from conventional magnets.
In 1 cm square area, of a cobalt-based magnetic material used in latest hard drives and other devices, you can store at the most 3 billion bits, or 3 gigabits of data.
www.earthtimes.org /articles/show/873.html   (503 words)

  
 Virginia Tech Department of Physics
Structure of a single-molecule magnet Mn12-acetate [Mn (blue), O (red), C (gray)] whose electronic and magnetic properties were calculated by Prof.
The electrodes, imaged by scanning electron microscopy, are used to study the electronic properties of molecules (molecular electronics) and of organic semiconductors (organic electronics).
View of the KEKB accelerator beamlines, acceleration cavities, and steering magnets, at the intersection with one of the injection beamlines.
www.phys.vt.edu /showcase/showcase.html   (1856 words)

  
 Post-docs
In practice, a single molecule magnet bridges a 1-3 nm gap between two nanoelectrodes and the electron transport properties are measured.
Given that many single-molecule magnets (SMMs) have well-defined anisotropy axes and exhibit quantum tunneling of the magnetization (QTM), we are developing new single-electron transistors (SETs), which incorporate these molecules as the current regulating electronic units.
We, therefore, plan to investigate the scenario in which current is allowed to flow through the molecule while the Zeeman levels are tuned to resonance.
www.physics.ucf.edu /~delbarco/html/post-docs.html   (341 words)

  
 ScienceDaily: Moldable, "Tunable" Magnets Make Their Debut
Lead Science author Mark J. MacLachlan and colleagues tweaked iron-and-polymer molecules, transforming them into a magnetic ceramic material, which was molded into various shapes.
Magnetic Fields Revealed In Technicolor (November 21, 2005) -- Vibrations of magnetization have for the first time been captured on camera by scientists at The University of Manchester revealing a rainbow of colours.
Because larger clusters are more strongly magnetic, or ferromagnetic, the researchers can tune the material's magnetism, by adjusting the temperature inside the pyrolysis chamber.
www.sciencedaily.com /releases/2000/02/000228080945.htm   (803 words)

  
 From the ACS Meeting: New Single-Molecule Magnets Reported
Among the single-molecule magnet pluses would be uniform size, solubility in organic solvents, and readily alterable peripheral ligands, among others.
The research challenge, he added, is to find better single-molecule magnets that function at higher temperatures.
-->3/27/2000 Researchers from Indiana University (Bloomington) disclosed this week that they've prepared several new single-molecule magnets.
www.laboratorynetwork.com /Content/News/article.asp?DocID={B157C05C-03F0-11D4-8C2F-009027DE0829}&Bucket=Materials+Science   (283 words)

  
 New vision of magnetic tunnelling (January 2002) - Physics World - PhysicsWeb
Ideally all the molecules are identical because they have been built chemically, which means that they can be characterized precisely and that any data can be analysed quantitatively (see Magnets, molecules and quantum mechanics Physics World March 1999 pp35-39).
The most studied of these molecules is manganese-12 acetate (Mn Within each molecule, the spins of the eight Mn ions (each with S = 2) are antiparallel to the spins of the four Mn ions (each with S = 3/2), giving Mn a total spin of S = 10.
With dimensions of about a nanometre, these magnets are usually composed of a magnetic core that is surrounded by organic complexes.
www.physicsweb.org /article/world/15/1/4   (441 words)

  
 ScienceDaily: 'Rule-breaking' Molecule Could Lead To Non-metal Magnets
While the molecule Wenthold's team has investigated is not found in the body and has no household name - it is referred to only by its chemical description, 5-dehydro-1,3-quinodimethane - it has a property that would raise the eyebrows of any observant student in a first-year chemistry course.
The compound is not the only molecule that exhibits such odd behavior in its surrounding cloud of electrons, but it is the first to be discovered that does not include a transition metal.
Radical molecules, which contain unpaired electrons and are thus more reactive than molecules without them, have gained household notoriety primarily because so-called "free radicals" in the bloodstream can damage healthy cells.
www.sciencedaily.com /releases/2004/02/040203235638.htm   (1286 words)

  
 UCF Department of Physics
"Quantum Superposition of High-Spin States in Single Molecule Magnet Ni4." Phys.
Nanoscale magnetic systems are excellent candidates for these studies due to the fact that one can go from quantum to classical regimes by changing size of the system under study.
One approach to this is by decreasing the size of a magnet to nanometers.
www.physics.ucf.edu /faculty_delbarco.php   (296 words)

  
 C&EN: SCIENCE & TECHNOLOGY - SINGLE-MOLECULE MAGNETS EVOLVE
Magnetic anisotropy is the nonuniform distribution of magnetic properties in a molecule or particle.
Electronic coupling between the two molecules shuts down quantum tunneling in the absence of an applied magnetic field that is observed in the individual molecules, indicating that the dimer or other SMMs might function as qubits for quantum computing.
In these compounds, some of which are magnets at room temperature, the magnetism arises from the collective unpaired electrons of the bulk material, similar to iron or cobalt metal particles.
pubs.acs.org /cen/science/8250/8250sci1.html   (3077 words)

  
 20050303ZantHvander
We use electromigration of gold wires on top of aluminum gates to measure the properties of the single molecule magnet Mn-12 (S = 10 ground state) and OPV-3.
Transport measurements show that the molecules are strongly coupled to the leads (level broadening of the same order as the charging energy) because of their unconventional gate effect.
Small organic molecules of different lengths (sulphur end functionalized oligo(cyclohexylidenes) which possess sigma-pi-sigma conjugation) have been trapped between the electrode pairs.
www.rug.nl /msc/news/colloquia/20050303ZantHvander   (203 words)

  
 - A short Scientific report, highlighting the main results achieved up to
A new addition to the family of single molecule magnets is reported: a Fe cage stabilised with benzoate and pyridonate ligands.
A cyclic dodecanuclear nickel complex is the first single molecule magnet based on nickel(II) centres; the material is also the highest spin molecule to show resonant quantum tunnelling of magnetisation.
Collaborative studies within the network have led to the discovery of two new single molecule magnets.
www.chim1.unifi.it /mnmag/winp/MidTerm.htm   (2534 words)

  
 Explore feature - Quantum Leap
Hill, who spent two and a half years as a postdoctoral associate at the National High Magnetic Field Laboratory in Tallahassee, had already worked with single-molecule magnets, and he and Christou decided to collaborate with three others on an NSF grant proposal probing the quantum properties of coupled molecules.
For one thing, the magnetic nature of the small molecules suggests that it may be feasible to engineer them into current classical computer architectures, Hill says.
Predicted to be something - no one knows quite what - the size of an atom or small molecule, this qubit will act as a zero and one at the same time.
rgp.ufl.edu /publications/explore/v09n3/quantum.html   (2063 words)

  
 Title page for ETD etd-11102004-173554
Chapter 3 is focused on the 0-d metal-metal bonded complex Ru2(3,5-Cl4C13H11N2)4Cl·C6H14 that exhibits large zero-field splitting as measured by magnetic susceptibility on oriented single crystals, and butterfly magnetic hysteresis loops, which are analyzed in the context of a phonon bottleneck mechanism.
Low-dimensional magnetic materials are of current interest due to their variability between quantum and classical magnetism.
Phase transitions for both complexes are observed and the magnetic contribution of the [Ni(hmp)(tBuEtOH)Cl]4 is calculated and compared to the experimental data in order to estimate the D-parameter.
etd.lib.fsu.edu /theses/available/etd-11102004-173554   (290 words)

  
 PhysOrgForum Science, Physics and Technology Discussion Forums -> can you make holograms?
Even the single molecule magnets I mentioned are dipoles.
You can make a magnet as small as a single molecule.
eg:telling a magnet to concentrate on one particle in a single material.
forum.physorg.com /index.php?showtopic=1936&view=getlastpost   (1087 words)

  
 Yamashita Team (Development and Application of Nano-Molecular Quantum Magnets)
This project is focused on unique nano-sized magnetic materials such as "Nano-wire single-molecule magnet", "Nano-ring single-molecule magnet", "Nano-dots wire", and "Nano-dots network", which will be synthesized by bottom-up (molecular) techniques.
Magnetic measurements under pressure and solid state NMR on Single-Chain Magnets
One of our curiosities is to see a boundary between quantum and bulk regimes on magnetic behaviors.
www.nanostruct-mater.jst.go.jp /theme-e/subject/07-yamashita.html   (157 words)

  
 CRYATAL ENGINEERING OF COORDINATION COMPOUNDS WITH NANOSCALE FEATURES
We report 55Mn NMR measurements on a single crystal of the single-molecule magnet (SMM) Mn12-bromoacetate below its blocking temperature (3K) in the range of 1.8-3K.
  The Mn3+ peaks are split by quadrupole interactions confirming the magnetic structure of the Mn12 core and complementing EPR measurements.
  Planned studies of angular variation in applied fields should provide new clues to the necessary transverse magnetic fields required for quantum tunneling of the magnetization to occur.
membership.acs.org /f/florida/Poster/Physical/Harter.htm   (196 words)

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