Wikipedia
Proximity Effect is a comic book series written by Scott Tucker and Aron Coleite. Penciled by David Nakayama. This OGN saw its first two issues published online, with the third available only as part of the trade paperback.
The idea for the series is that some humans have the capacity for superhuman abilities, but only when within a certain distance of another special human. This "proximity effect" has been studied by the US government and private citizens. Since the 'generator' individuals are infinitely rarer than the "receivers", a race has begun to find these people and sequence their genes for that particular trait.
Proximity effect may refer to:
- Proximity effect (atomic physics)
- Proximity effect (audio), an increase in bass or low frequency response when a sound source is close to a microphone
- Proximity Effect (comics), a comic book series written by Scott Tucker and Aron Coleite
- Proximity effect (electromagnetism)
- Proximity effect (electron beam lithography), a phenomenon in electron beam lithography (EBL)
- Proximity effect (superconductivity), a term used in the field of superconductivity
- The Proximity Effect (Nada Surf album), 1998
- The Proximity Effect (Laki Mera album), 2011
At the atomic level, when two atoms come into proximity, the highest energy, or valence, orbitals of the atoms change substantially and the electrons on the two atoms reorganize. One way to probe a correlated state is through the proximity effect. This phenomenon occurs when the correlations present in one degenerate system "leak" into another one with which it is in chemical equilibrium. See also quantum tunneling, Casimir effect, van der Waals force.
Category:Nuclear physics
In a conductor carrying alternating current, if currents are flowing through one or more other nearby conductors, such as within a closely wound coil of wire, the distribution of current within the first conductor will be constrained to smaller regions. The resulting current crowding is termed as the proximity effect. This crowding gives an increase in the effective resistance of the circuit, which increases with frequency.
The proximity effect in audio is an increase in bass or low frequency response when a sound source is close to a microphone.
Proximity effect or Holm-Meissner effect is a term used in the field of superconductivity to describe phenomena that occur when a superconductor (S) is placed in contact with a "normal" (N) non-superconductor. Typically the critical temperature T of the superconductor is suppressed and signs of weak superconductivity are observed in the normal material over mesoscopic distances. The proximity effect is known since the pioneering work by R. Holm and W. Meissner. They have observed zero resistance in SNS pressed contacts, in which two superconducting metals are separated by a thin film of a non-superconducting (i.e. normal) metal. The discovery of the supercurrent in SNS contacts is sometimes mistakenly attributed to B. Josephson 1962 work, yet the effect was known long before his publication and was understood as the proximity effect.
The proximity effect in electron beam lithography (EBL) is the phenomenon that the exposure dose distribution, and hence the developed pattern, is wider than the scanned pattern, due to the interactions of the primary beam electrons with the resist and substrate. These cause the resist outside the scanned pattern to receive a non-zero dose.
Important contributions to weak-resist polymer chain scission (for positive resists) or crosslinking (for negative resists) come from electron forward scattering and backscattering. The forward scattering process is due to electron-electron interactions which deflect the primary electrons by a typically small angle, thus statistically broadening the beam in the resist (and further in the substrate). The majority of the electrons do not stop in the resist but penetrate the substrate. These electrons can still contribute to resist exposure by scattering back into the resist and causing subsequent inelastic or exposing processes. This backscattering process originates e.g. from a collision with a heavy particle (i.e. substrate nucleus) and leads to wide-angle scattering of the light electron from a range of depths (micrometres) in the substrate. The Rutherford backscattering probability increases quickly with substrate nuclear charge.
The above effects can be approximated by a simple two-gaussian model where a perfect point-like electron beam is broadened to a superposition of a Gaussian with a width α of a few nanometers to order tens of nanometers, depending on the acceleration voltage, due to forward scattering and a Gaussian with a width β of the order of a few micrometers to order tens due to backscattering, again depending on the acceleration voltage but also on the materials involved:
$$PSF(r)=\frac{1}{\pi (1+\eta)} \left[\frac{1}{\alpha^2} e^{-\frac{r^2}{\alpha^2}} + \frac{\eta}{\beta^2} e^{-\frac{r^2}{\beta^2}}\right]$$
η is of order 1 so the contribution of backscattered electrons to the exposure is of the same order as the contribution of 'direct' forward scattered electrons. α, β and η are determined by the resist and substrate materials and the primary beam energy. The two-gaussian model parameters, including the development process, can be determined experimentally by exposing shapes for which the Gaussian integral is easily solved, i.e. donuts, with increasing dose and observing at which dose the center resist clears or does not clear.
A thin resist with a low electron density will reduce forward scattering. A light substrate (light nuclei) will reduce backscattering. When electron beam lithography is performed on substrates with 'heavy' films, such as gold coatings, the backscatter effect will (depending on thickness) significantly increase. Increasing beam energy will reduce the forward scattering width, but since the beam penetrates the substrate more deeply, the backscatter width will increase.
The primary beam can transfer energy to electrons via elastic collisions with electrons and via inelastic collision processes such as impact ionization. In the latter case, a secondary electron is created and the energy state of the atom changes, which can result in the emission of Auger electrons or X-rays. The range of these secondary electrons is an energy-dependent accumulation of (inelastic) mean free paths; while not always a repeatable number, it is this range (up to 50 nanometers) that ultimately affects the practical resolution of the EBL process. The model described above can be extended for these effects.