The small-particle, thick-double-layer approximation ${\mu }_e=2ϵ\zeta /(3\eta )$ under its linear electrokinetic assumptions.

An arenium ion is a positively charged intermediate in which electrophilic addition has interrupted the original aromatic delocalization. Lone-pair donors can stabilize contributors that place positive charge at adjacent positions.

A Friedel-Crafts reaction introduces an alkyl or acyl group onto an aromatic ring by electrophilic aromatic substitution, commonly with activation by a Lewis acid. Alkylation and acylation are related reaction families but have different intermediate chemistry.

An alkylation pathway can involve carbocation-like rearrangements and can promote repeated substitution. An acylation transfers an acyl group through an activated electrophile, often described using an acylium ion, and its carbonyl substituent generally deactivates the product toward further substitution. These differences explain why the two variants are not interchangeable methods of adding a carbon substituent.

Aromatic oxazolination introduces an oxazolinyl group at an aromatic C–H position. Activating 2-Oxazolidinone with triflic anhydride supplies an electrophilic carbon that an electron-rich arene can attack.

Aromatic nitration replaces an aromatic hydrogen with a nitro group. In a common pathway, aromatic attack on a nitronium ion forms a Wheland intermediate and deprotonation restores aromaticity.

An electrophile adds at an aromatic carbon already bearing a substituent; rearomatization can expel that substituent instead of the newly added proton.

Formation of a carbon–sulfur bond by reaction of an electron-rich carbon centre with electrophilic sulfur, followed where needed by deprotonation.

The cytochrome b6f complex transfers electrons between the two photosystems in oxygenic photosynthesis and contributes to proton-gradient formation. Its regulated throughput links lumen conditions to intersystem electron flow.

Plastoquinone is a mobile lipid-soluble electron carrier in photosynthetic membranes. Its reduction state helps communicate the balance of electron supply and demand between photosystems.

A copper-containing electron carrier delivering electrons from the cytochrome-b6f pathway to photosystem I in many oxygenic photosynthetic organisms.

Transfer of reducing equivalents between a cell and an external acceptor or donor, by direct redox-protein contact, conductive structures or soluble mediators.

An illumination lens controlling how an electron beam reaches the probe-forming optics or specimen. Its settings affect current, convergence and illumination geometry.

The principal specimen-adjacent focusing lens of an electron microscope. Its role depends on the mode: forming a small incident probe in scanned imaging differs from forming an enlarged transmitted image in conventional imaging.^[ref]

The electric current delivered per transverse probe area per solid angle. For a uniform circular probe of diameter $d$ and a small convergence semiangle $\alpha$, one convention is $\beta =4I/({\pi }^2{d}^2{\alpha }^2)$. State the accelerating voltage, angular convention and whether brightness is reduced by a voltage factor before comparing sources. A smaller aperture changes current as well as convergence; finite electron beam brightness prevents arbitrary current in an arbitrarily small probe.

A Wigner crystal is an ordered arrangement of electrons stabilized by their mutual repulsion when localization costs sufficiently little kinetic or thermal energy. In a degenerate low-density gas, the Coulomb-to-kinetic energy ratio of an electron gas increases with mean spacing. Classical electrons can also order at large Coulomb-to-thermal coupling, as in electron crystallization on liquid helium. A neutralizing background or confining environment is needed to discuss a stable electron assembly. Dimension, screening and disorder affect the transition.

Energy-loss near-edge structure is the detailed shape near an inner-shell excitation edge in an electron energy loss spectroscopy measurement. Transition probabilities sample accessible unoccupied electronic states, so local bonding and orientation affect the edge shape as well as elemental identity.

Comparing two specimens containing the same element can therefore reveal different electronic environments. Interpretation must account for instrumental energy resolution, the incident beam's energy spread and lifetime broadening of the states involved. ^[ref] A small peak difference alone does not uniquely determine one atomic arrangement.

Antiferromagnetic exchange between a localized magnetic moment and conduction electrons produces strong low-energy correlations and screening of the moment. In a dilute magnetic-impurity metal, a resistance minimum and a low-temperature logarithmic increase are characteristic signatures over an appropriate temperature range. The strong-coupling low-temperature regime cannot be obtained by extending the logarithm indefinitely.

A strongly correlated material whose low-energy electronic quasiparticles have a very large thermodynamic effective mass. An enhanced electronic heat capacity coefficient, spin susceptibility and quantum-oscillation cyclotron effective mass are complementary signatures; they need not all be related by a single isotropic band mass. A Kondo lattice is an important setting for such behaviour. In CeAl3, low-temperature specific heat and quadratic resistivity provided an early quantitative example.^[ref]

Electron correlation caused by the need for multiple important configurations, often when several molecular orbitals are nearly degenerate. Stretching a homonuclear two-electron bond makes a single doubly occupied orbital retain unphysical ionic contributions; a suitable combination of configurations cancels them.

The correlated instantaneous avoidance of electrons beyond a single Slater determinant. It can remain important even when one configuration dominates, as for an isolated closed-shell helium atom; it is distinct from the near-degeneracy problem of static electron correlation.