#diamagnetism

[biology-geology-beaches-india]

TSRNOSS. Page 156.

[materialsscienceandengineering]

Scholes finds novel magnetic field effect in diamagnetic molecules

The Princeton University Department of Chemistry publishes research this week proving that an applied magnetic field will interact with the electronic structure of weakly-magnetic, or diamagnetic, molecules to induce a magnetic-field effect that, to their knowledge, has never before been documented.

With the experimental application of magnetic fields up to 25 Tesla, molecules with little intrinsic magnetism exhibit magneto-sensitive optical and photophysical properties, according to the paper, "Ring currents modulate optoelectronic properties of aromatic chromophores at 25 Tesla," published in the Proceedings of the National Academy of Sciences (PNAS).

Gregory Scholes, the William S. Todd Professor of Chemistry, and Bryan Kudisch, a fifth-year graduate student and the paper's lead author, said the discovery could allow scientists to fundamentally change the electronic and photophysical properties of some classes of molecules by using the magnetic field as a "handle."

Experimenting with a magnetic field almost 1M times stronger than that of the Earth, researchers in the Scholes Group were able to modify the optoelectronic properties of model nonmagnetic organic chromophores. The modifications, according to the paper, arise from the induction of ring currents in the aromatic molecules.

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[materialsscienceandengineering]

Unraveling the magnetism of a graphene triangular flake

Graphene is a diamagnetic material, this is, unable of becoming magnetic. However, a triangular piece of graphene is predicted to be magnetic. This apparent contradiction is a consequence of "magic" shapes in the structure of graphene flakes, which force electrons to "spin" easier in one direction. Triangulene is a triangular graphene flake, which possesses a net magnetic moment: it is a graphene nanometer-size magnet. This magnetic state opens fascinating perspectives on the use of these pure-carbon magnets in technology.

However, the robust predictions of triangulene magnetism stumbled with the absence of clear experimental proofs, because the production of triangulene by organic synthesis methods in solution was difficult. The bi-radical character of this molecule caused it to be very reactive and difficult to fabricate, and the magnetism appears to be very elusive in those few successful cases.

In a new study, published in Physical Review Letters, this challenge was revisited using a scanning tunneling microscope (STM). After assembling a triangular-like piece of graphene on a clean gold surface, high-resolution scanning tunneling spectroscopy measurements revealed that this compound has a net magnetic state characterized by a spin S=1 ground state and, therefore, that this molecule is a small, pure carbon paramagnet. These results are the first experimental demonstration of a high-spin graphene flake.

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[materialsscienceandengineering]

"Anti" Magnetic water and Levitating Graphite by Diamagnetism

Diamagnetism is the property of a substance to be repelled by a magnetic field. Interestingly enough, water shows this effect. We build a simple, but very sensitive detector to show this. We also show pyrolytic carbon that is so diamagnetic that it can float above magnets if they are arranged the right way.

Water is diamagnetic, meaning it's slightly repelled by a magnetic field. But in everyday life this is almost impossible to notice. We need to build a very sensitive detector to see it. 

Just get a basin of water and float a styrofoam block in it. Styrofoam is very light and so even the small repulsive force of a test tube of water will have a noticeable push on it. Push the test tube of water into the center of the block and simply hold a strong neodymium magnet as close as possible to the tube without touching it. It's a very small force, but eventually the block will start moving away from the magnet. 

Pyrolytic graphite, also called pyrolytic carbon, exhibits the same effect and can even be made to levitate on top of a magnet. A single magnet is unstable since the graphite will like to fall off the side. But having four magnets and arranging them like in the video will create a "void" in the center that the graphite "falls" into and remains stably levitated.

[teachersource]

Michael Faraday was born on September 22, 1791. An English scientist who contributed to the study of electromagnetism and electrochemistry. His main discoveries include the principles underlying electromagnetic induction, diamagnetism and electrolysis. He was one of the most influential scientists in history. It was by his research on the magnetic field around a conductor carrying a direct current that Faraday established the basis for the concept of the electromagnetic field in physics. Faraday also established that magnetism could affect rays of light and that there was an underlying relationship between the two phenomena. His inventions of electromagnetic rotary devices formed the foundation of electric motor technology, and it was largely due to his efforts that electricity became practical for use in technology.

[teachersource]

John Tyndall was born on August 2, 1820. A prominent 19th-century Irish physicist, his initial scientific fame arose in the 1850s from his study of diamagnetism. Later he made discoveries in the realms of infrared radiation and the physical properties of air, proving the connection between atmospheric CO2 and what is now known as the greenhouse effect in 1859. Tyndall also published more than a dozen science books which brought state-of-the-art 19th century experimental physics to a wide audience.

[hsmagnet]

High Temperature Can Make Magnets Lose Magnetism Quickly

High Temperature Can Make Magnets Lose Magnetism Quickly

High Temperature Can Make Magnets Lose Magnetism Quickly A magnet will lose some magnetism immediately when it encounters a high temperature that exceeds its own tolerance. How much high temperature does it need? This depends on the coercive force of the magnet, which is usually expressed by the letter after the magnet grade, such as N40H, the maximum magnetic energy product is 40, and H…

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[hsmagnet]

The Difference Between Maximum Working Temperature and Curie Temperature of Magnet

The Difference Between Maximum Working Temperature and Curie Temperature of Magnet

The Difference Between Maximum Working Temperature and Curie Temperature of Magnet

Maybe some people think the maximum working temperature of magnet is same as its Curie temperature. Actually, this is a mistake.

The magnetic material can be divided into 5 kinds: ferromagnetism, ferrimagnetism, anti-ferromagnetism, paramagnetism, diamagnetism. Iron, Cobalt and Nickel are ferromagnetic material,…

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