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The Penning–Malmberg trap (PM trap), named after Frans Penning and John Malmberg, is an electromagnetic device used to confine large numbers of charged particles of a single sign of charge. Much interest in Penning–Malmberg (PM) traps arises from the fact that if the density of particles is large and the temperature is low, the gas will ...
A cylindrical version of a Penning trap, with open endcaps to permit axial access. B indicates the magnetic field, and E indicates the electric field used for storage of the particles in the trap centre. A Penning trap is a device for the storage of charged particles using a homogeneous magnetic field and a quadrupole electric field.
Ball-and-stick model of a sulfamic acid zwitterion as it occurs in the crystal state. [4]The compound is well described by the formula H 3 NSO 3, not the tautomer H 2 NSO 2 (OH). The relevant bond distances are 1.44 Å for the S=O and 1.77 Å for the S–N.
[1] [2] [3] Introduced by Gilbert N. Lewis in his 1916 article The Atom and the Molecule, a Lewis structure can be drawn for any covalently bonded molecule, as well as coordination compounds. [4] Lewis structures extend the concept of the electron dot diagram by adding lines between atoms to represent shared pairs in a chemical bond.
In solid-state physics, the Poole–Frenkel effect (also known as Frenkel–Poole emission [1]) is a model describing the mechanism of trap-assisted electron transport in an electrical insulator. It is named after Yakov Frenkel , who published on it in 1938, [ 2 ] extending the theory previously developed by H. H. Poole.
Spin trapping is an analytical technique employed in chemistry [1] and biology [2] for the detection and identification of short-lived free radicals through the use of electron paramagnetic resonance (EPR) spectroscopy. EPR spectroscopy detects paramagnetic species such as the unpaired electrons of free radicals.
Figure 4. Electronic band structure in the nearly free electron picture. Away from the Brillouin zone boundary the electron wave function has plane wave character and the dispersion relation is parabolic. At the Brillouin zone boundary the wave function is a standing wave composed of an incoming and a Bragg-reflected wave.
A uniform electron gas at zero temperature is characterised by a single dimensionless parameter, the so-called Wigner–Seitz radius r s = a / a b, where a is the average inter-particle spacing and a b is the Bohr radius. The kinetic energy of an electron gas scales as 1/r s 2, this can be seen for instance by considering a simple Fermi gas.