How does electron multiplier work?
An electron multiplier is a vacuum-tube structure that multiplies incident charges. If an electric potential is applied between this metal plate and yet another, the emitted electrons will accelerate to the next metal plate and induce secondary emission of still more electrons.
How does a Channeltron work?
Instead of a series of discrete plates, a Channeltron electron multiplier uses a high resistance semiconductor material that also has high secondary electron emissivity. Gains of a Channeltron are typically 2 X 10E7 to 2 X 10E8. Channel plate electron multipliers are commonly used on X-ray Photo electron spectrometers.
What is the purpose of electron multiplier?
An electron multiplier is used to detect the presence of ion signals emerg- ing from the mass analyzer of a mass spectrometer. It is essentially the “eyes” of the instrument (Figure 1). The task of the electron multiplier is to detect every ion of the selected mass passed by the mass filter.
What is an electron multiplier used for?
How does a dynode work?
A dynode is an electrode in a vacuum tube that serves as an electron multiplier through secondary emission. Secondary emission occurs at the surface of each dynode. Such an arrangement is able to amplify the tiny current emitted by the photocathode, typically by a factor of one million.
How is an electron multiplier made out of?
In the 1960s electron multipliers were made out of a series of Oxygen treated copper beryllium (CuBe) plates. Copper with 3 to 4% beryllium that is heat treated with oxygen has a secondary electron yield of approximately 3 (varies slightly for kinetic energies between 100 up to 1500V)
How many electrons does a microchannel electron multiplier gain?
Each channel has a diameter of 10-100 μm. The electron gain for one microchannel plate can be around 10 4 -10 7 electrons. In mass spectrometry electron multipliers are often used as a detector of ions that have been separated by a mass analyzer of some sort.
How are electron multipliers used in mass spectrometry?
In mass spectrometry electron multipliers are often used as a detector of ions that have been separated by a mass analyzer of some sort. They can be the continuous-dynode type and may have a curved horn-like funnel shape or can have discrete dynodes as in a photomultiplier.
What are the weaknesses of an electron multiplier?
Electron multipliers have a few weaknesses as detectors. Among them is their inability to readily detect negative ions and their mass discrimination.