Mass Spectrometric Techniques

Knudsen effusion mass spectrometry: Current and future approaches

“…Typically, the filament is heated with a few volts and several amperes up to 2000-3000 K for emission to start. 73 The relationship between the electron current density, i e , and temperature, T, and the properties of the filament are given by the Richardson equation 73 :…”

“…Most instruments use some type of electron multiplier. 73,109 A conventional electron multiplier contains a conversion dynode, which converts the stream of ions to electrons. This is followed by a series of dynodes (usually 16-20) set up for a "cascading" effect where each dynode ejects more electrons than strike it.…”

“…Most instruments use some type of electron multiplier 73,109 . A conventional electron multiplier contains a conversion dynode, which converts the stream of ions to electrons.…”

“…Note that the entire ionization assembly is at a high voltage, typically 5–10 kV. Typically, the filament is heated with a few volts and several amperes up to 2000–3000 K for emission to start 73 . The relationship between the electron current density, i e , and temperature, T , and the properties of the filament are given by the Richardson equation 73 : $$$$ {i}_{\mathrm{e}}\propto {T}^2\exp \left(-\frac{\beta \phi}{T}\right) $$$$ …”

“…First, consider a Faraday cup. 73,109,110 This is simply a cup or cage (typically several millimeters) that collects ions from the ion sorter, generally with a front electrode to prevent the generated electrons on impact from escaping. The ions hitting the metal produce a small current as they neutralize.…”