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A meridional ray is a ray that passes through the axis of an optical fiber. A skew ray is a ray that travels in a non-planar zig-zag path and never crosses the axis of an optical fiber. A guided ray, bound ray, or trapped ray is a ray in a multi-mode optical fiber, which is confined by the core.
Tunneling current is exponentially dependent on the separation of the sample and the tip, typically reducing by an order of magnitude when the separation is increased by 1 Å (0.1 nm). [5] Because of this, even when tunneling occurs from a non-ideally sharp tip, the dominant contribution to the current is from its most protruding atom or orbital.
In scanning tunneling microscopy, a metal tip is moved over a conducting sample without making physical contact. A bias voltage applied between the sample and tip allows a current to flow between the two. This is as a result of quantum tunneling across a barrier; in this instance, the physical distance between the tip and the sample
Tunneling applications include the tunnel diode, [5] quantum computing, flash memory, and the scanning tunneling microscope. Tunneling limits the minimum size of devices used in microelectronics because electrons tunnel readily through insulating layers and transistors that are thinner than about 1 nm.
The Hartman effect is the tunneling effect through a barrier where the tunneling time tends to a constant for large barriers. [30] [31] This could, for instance, be the gap between two prisms. When the prisms are in contact, the light passes straight through, but when there is a gap, the light is refracted.
Typical X-ray detectors for electron microscopes cover only a small solid angle, which makes X-ray detection relatively inefficient since X-rays are emitted from the sample in every direction. However, detectors covering large solid angles have been recently developed, [ 27 ] and atomic resolution X-ray mapping has even been achieved.
The Hartman effect is the tunneling effect through a barrier where the tunneling time tends to a constant for thick enough barriers. This was first described by Thomas E. Hartman in 1962. [ 1 ] Although the effect was first predicted for quantum particles governed by the Schrödinger equation , it also exists for classical electromagnetic wave ...
Fowler–Nordheim tunneling is the wave-mechanical tunneling of electrons through a rounded triangular barrier created at the surface of an electron conductor by applying a very high electric field. Individual electrons can escape by Fowler–Nordheim tunneling from many materials in various different circumstances.