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In organic chemistry, umpolung (German: [ˈʔʊmˌpoːlʊŋ]) or polarity inversion is the chemical modification of a functional group with the aim of the reversal of polarity of that group. [ 1 ] [ 2 ] This modification allows secondary reactions of this functional group that would otherwise not be possible. [ 3 ]
Yet, before the experiments of Stanciu and Hansteen, all-optical controllable magnetization reversal in a stable magnetic state was considered impossible. [ 1 ] In quantum field theory and quantum chemistry the effect where the angular momentum associated to the circular motion of the photons induces an angular momentum in the electrons is ...
Polarity inversion may refer to: Polarity inversion (chemistry) (aka Umpolung ), in organic chemistry Polarity inversion (differential pairs) , swapping of positive and negative wires in differential signal links
Magnetic polarizability likewise refers to the tendency for a magnetic dipole moment to appear in proportion to an external magnetic field. Electric and magnetic polarizabilities determine the dynamical response of a bound system (such as a molecule or crystal) to external fields, and provide insight into a molecule's internal structure. [2] "
Magnetochemistry is concerned with the magnetic properties of chemical compounds and elements. Magnetic properties arise from the spin and orbital angular momentum of the electrons contained in a compound. Compounds are diamagnetic when they contain no unpaired electrons. Molecular compounds that contain one or more unpaired electrons are ...
A rotating magnetic field is produced by external magnetic coils perpendicular to the axis of the machine, and the direction of this field is rotated about the axis. When the rotation frequency is between the ion and electron gyro-frequencies, the electrons in the plasma co-rotate with the magnetic field (are "dragged"), producing current and ...
The work function W for a given surface is defined by the difference [1] =, where −e is the charge of an electron, ϕ is the electrostatic potential in the vacuum nearby the surface, and E F is the Fermi level (electrochemical potential of electrons) inside the material.
Mathematical modeling and experiment have both shown that periodically arrayed conducting elements (non-magnetic by nature) respond predominantly to the magnetic component of incident electromagnetic fields. The result is an effective medium and negative μ eff over a band of frequencies. The permeability was verified to be the region of the ...