Vacuum level
Encyclopedia
In physics, the vacuum level refers to the energy of a free stationary electron
that is outside of any material (it is in a perfect vacuum
).
It may be taken as infinitely far away from a solid or modified to be defined near a surface. Its definition and measurement are often discussed in UPS literature, for example As the vacuum level is a property of the electron and free space, it is often used as the level of alignment for the energy level
s of two different materials. The vacuum level alignment approach may or may not hold due to details of the interface. It is particularly important in the design of vacuum device components such as cathodes.
The phrase "vacuum level" also occurs often in texts on squeezed light where it refers to an unsqueezed measurement. For example, "Thus, when the noise level in the spectrum analyzer shows broadband squeezing below the vacuum level, it also indicates the presence of entanglement between upper and lower sidebands."
Note that the phrase "vacuum level" may also refer to a measurement of residual pressure in a vacuum system or a device that uses differential pressure such as a carburetor
but this usage should be very clear from context.
Electron
The electron is a subatomic particle with a negative elementary electric charge. It has no known components or substructure; in other words, it is generally thought to be an elementary particle. An electron has a mass that is approximately 1/1836 that of the proton...
that is outside of any material (it is in a perfect vacuum
Vacuum
In everyday usage, vacuum is a volume of space that is essentially empty of matter, such that its gaseous pressure is much less than atmospheric pressure. The word comes from the Latin term for "empty". A perfect vacuum would be one with no particles in it at all, which is impossible to achieve in...
).
It may be taken as infinitely far away from a solid or modified to be defined near a surface. Its definition and measurement are often discussed in UPS literature, for example As the vacuum level is a property of the electron and free space, it is often used as the level of alignment for the energy level
Energy level
A quantum mechanical system or particle that is bound -- that is, confined spatially—can only take on certain discrete values of energy. This contrasts with classical particles, which can have any energy. These discrete values are called energy levels...
s of two different materials. The vacuum level alignment approach may or may not hold due to details of the interface. It is particularly important in the design of vacuum device components such as cathodes.
The phrase "vacuum level" also occurs often in texts on squeezed light where it refers to an unsqueezed measurement. For example, "Thus, when the noise level in the spectrum analyzer shows broadband squeezing below the vacuum level, it also indicates the presence of entanglement between upper and lower sidebands."
Note that the phrase "vacuum level" may also refer to a measurement of residual pressure in a vacuum system or a device that uses differential pressure such as a carburetor
Carburetor
A carburetor , carburettor, or carburetter is a device that blends air and fuel for an internal combustion engine. It is sometimes shortened to carb in North America and the United Kingdom....
but this usage should be very clear from context.