An energy filter selects electrons according to energy. In cryo-electron microscopy, rejecting energy-loss electrons can reduce background, but filtering cannot reverse chemical damage or remove every source of scattering noise.

The contrast transfer function describes how an imaging system transfers object information at different spatial frequencies. In phase-contrast electron microscopy, defocus and aberrations can suppress or reverse particular components, requiring calibrated correction and complementary data.

A hole in the upper valence manifold associated near a chosen propagation axis with the $j=3/2$, $m_j=\pm 3/2$ branch. Its band curvature is relatively small, hence its effective mass relatively large. The label is direction dependent in a general anisotropic band structure.

A hole in the $j=3/2$, $m_j=\pm 1/2$ valence branch near a specified axis. Its curvature and effective mass differ from those of the heavy-hole branch; confinement and strain can split branches that are degenerate at the bulk zone centre.

Let $x_{\mathrm{zp}}=\sqrt{\hslash /(2m\omega )}$ and $\eta =x_0/(2x_{\mathrm{zp}})$. The normalized first-order truncation is $(|0⟩+\eta |1⟩)/\sqrt{1+{\eta }^2}$. Its mean displacement is $2\eta x_{\mathrm{zp}}/(1+{\eta }^2)$, agreeing with $x_0$ only at small $|\eta |$. The exact translated ground state is a coherent state whose expansion contains all number states and has mean occupation ${\eta }^2$. Correct linear response does not justify extrapolating a truncated state to large fields.

The compact interfacial region associated with finite ion closest approach and specifically adsorbed charge. A diffuse electrolyte layer lies beyond it.

An ion with the same charge sign as the surface or fixed charge being screened. In a simple diffuse layer it is depleted near a similarly charged surface.

The spatially extended ionic atmosphere screening a charged surface beyond the compact Stern layer.

The electrokinetic potential at a hydrodynamic slipping plane relative to bulk solution. It need not equal the potential at the physical solid surface.

Overcompensation of an initial interfacial charge by adsorbed species or correlated ions, so the charge or potential inferred outside the compact interfacial region has the opposite sign. Screening of a fixed boundary charge alone is not the same mechanism.

A model separating a compact interfacial layer from a diffuse ion distribution. Specified adsorption and boundary conditions determine the potential at the outer compact-layer boundary; a diffuse-layer equation alone does not determine specific adsorption.

A dimensionless ratio comparing surface conduction with bulk conduction over a characteristic length. With pore radius r and surface conductance $K_s$, one convention is $\mathrm{Du}=K_s/(\sigma r)$; the cylindrical surface-to-bulk conductance ratio is twice this value.

A surface can change its surface charge density as its local electric potential and solution composition change, for example through reversible ionization or ion adsorption. This couples the surface reaction equilibrium to the surrounding electric double layer. Fixed-charge and fixed-potential models are limiting boundary conditions rather than interchangeable descriptions. Salt or pH changes can therefore alter both electrostatic screening and the repulsion amplitude.

A detuned optical drive still admixes a decaying excited state. Its spontaneous scattering rate is of order $\Gamma |\Omega {|}^2/(4{\Delta }^2)$ for weak far-detuned driving with coupling $\hslash \Omega /2$. Increasing detuning at fixed optical power reduces both unwanted scattering and useful coherent coupling.

The electric dipole operator is the charge-weighted position operator of a system. It is odd under parity and transforms as a rank-one spherical tensor operator. In the nonrelativistic electric-dipole approximation it acts on spatial coordinates without directly changing spin, explaining the parity, angular-momentum and approximate spin selection rules.

Electronic propagation through a device region with few momentum-randomizing scattering events. The mean free path should exceed the relevant trajectory length. Boundary specularity and aperture geometry can matter separately from the bulk mobility; electron phase coherence is an additional condition for interference.

An electric current that reverses direction periodically. A sinusoidal alternating current has the displayed form, where $I_0$ is its peak amplitude, $\omega$ its angular frequency, and $\phi$ its phase.

A primary battery is designed to deliver stored chemical energy through discharge rather than to recover that energy repeatedly by electrical charging. The distinction concerns the practical cell design and reaction reversibility, not whether a balanced chemical equation can be written in both directions.

During discharge, coupled oxidation and reduction at the electrodes supply an external electric current. Reaction products, morphology changes and parasitic processes determine how much active material remains accessible. A rechargeable battery instead manages those changes sufficiently well to recover useful capacity over repeated cycles; nominal chemical reversibility alone does not establish that capability.

An electrode whose discharge transforms the active compound into different phases rather than merely reversibly inserting a small ion.

Charge released per specified active or composite mass under complete stoichiometric utilization. For $n$ electrons per formula unit, active-material capacity is $nF/(3.6M)$ in mAh per gram.