Video Experimental Relacionado
Updated: Jun 26, 2026
09:06
Visualizing Uniaxial-strain Manipulation of Antiferromagnetic Domains in Fe1+YTe Using a Spin-polarized Scanning Tunneling Microscope
Published on: March 24, 2019
La conmutación reversible del magnetismo en los superátomos Au25 protegidos con tiolato
Manzhou Zhu1, Christine M Aikens, Michael P Hendrich
1Department of Chemistry, Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, Pennsylvania 15213, USA.
Journal of the American Chemical Society
|January 31, 2009
Resumen
Descubrimos que las nanopartículas de oro con 25 átomos de oro (Au) exhiben magnetismo conmutable. Sus propiedades magnéticas dependen de su estado de carga, lo que ofrece nuevas posibilidades para los nanomateriales.
Área de la Ciencia:
- Ciencia de los nanomateriales Ciencia de los nanomateriales
- Química cuántica es la química cuántica.
- Física del estado sólido Física del estado sólido
Sus antecedentes:
- Las nanopartículas de oro exhiben propiedades electrónicas y ópticas únicas.
- El control del magnetismo a nanoescala es crucial para aplicaciones avanzadas.
Objetivo del estudio:
- Para investigar el cambio reversible del paramagnetismo en las nanopartículas de oro.
- Para aclarar la estructura electrónica y el origen del magnetismo en las nanopartículas Au.
Principales métodos:
- Síntesis de nanopartículas de oro atómicamente monodispersas (Au25) y SR18)
- Manipulación del estado de carga de las nanopartículas.
- Espectroscopía de resonancia paramagnética de electrones (EPR). espectroscopia de resonancia paramagnética de electrones (EPR). espectroscopia de resonancia paramagnética de electrones (EPR). espectroscopia de resonancia paramagnética de electrones (EPR). espectroscopia de resonancia paramagnética de electrones (EPR). espectroscopia de resonancia paramagnética de electrones (EPR).
- Cálculos de la teoría funcional de la densidad (DFT).
Principales resultados:
- Se ha demostrado la conmutación reversible del paramagnetismo en las nanopartículas Au.
- Se estableció que el magnetismo está presente en el estado de carga neutral y ausente en el estado aniónico.
- Los estudios EPR y DFT revelaron un espín no emparejado con carácter similar a P deslocalizado en el núcleo Au 13 .
Conclusiones:
- Las nanopartículas Au{25) }{SR}{18) pueden considerarse superátomos protegidos por ligandos.
- El estado de carga es un factor clave para controlar las propiedades magnéticas de estas nanopartículas.
- Los hallazgos ofrecen información sobre el magnetismo fundamental del oro a nanoescala.
Más Videos Relacionados
Videos de Conceptos Relacionados
01:31Ferromagnetism
Materials like iron, nickel, and cobalt consist of magnetic domains, within which the magnetic dipoles are arranged parallel to each other. The magnetic dipoles are rigidly aligned in the same direction within a domain by quantum mechanical coupling among the atoms. This coupling is so strong that even thermal agitation at room temperature cannot break it. The result is that each domain has a net dipole moment. However, some materials have weaker coupling, and are ferromagnetic at lower...
01:28Types Of Superconductors
A superconductor is a substance that offers zero resistance to the electric current when it drops below a critical temperature. Zero resistance is not the only interesting phenomenon as materials reach their transition temperatures. A second effect is the exclusion of magnetic fields. This is known as the Meissner effect. A light, permanent magnet placed over a superconducting sample will levitate in a stable position above the superconductor. High-speed trains that levitate on strong...
03:02Colors and Magnetism
Color in Coordination Complexes
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human eye.
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human eye.
02:33Preparation and Reactions of Thiols
Thiols are prepared using the hydrosulfide anion as a nucleophile in a nucleophilic substitution reaction with alkyl halides. For instance, bromobutane reacts with sodium hydrosulfide to give butanethiol.
01:27π Electron Effects on Chemical Shift: Overview
An applied magnetic field causes loosely bound π-electrons in organic molecules to circulate, producing a local or induced diamagnetic field over a large spatial volume. As the molecules tumble in solution, the field generated by π-electrons in spherical substituents results in a zero net field. However, the net field generated by π-electrons in non-spherical substituents is not zero. The effect of this induced field depends on the orientation of the molecule with respect to B0, resulting in...
01:30Paramagnetism
Paramagnets are materials with unpaired electrons that possess a finite magnetic moment. In the absence of a magnetic field, these moments are randomly oriented, and thus the net moment is zero. Under an external field, a torque acting on the moments tends to align them along the field's direction. However, the random thermal motion of electrons produces a torque opposite to the external field and tries to disorient the moments. These two competing effects align only a few moments along the...