 thumb|300px|mass spectrometer ei/ci ion source an ion source is a device that creates atomic and molecular ions. ion sources are used to form ions for mass spectrometers, optical emission spectrometers, particle accelerators, ion implanters and ion engines. ==electron ionization== thumb|right|300 px|electron ionization source schematic electron ionization is widely used in mass spectrometry, particularly for organic molecules. the gas phase reaction producing electron ionization is :m + e^- \to m^{+\bullet} + 2e^- where m is the atom of molecule being ionized, e^- is the electron, and m^{+\bullet} is the resulting ion. the electrons may be created by an arc discharge between a cathode and an anode. an electron beam ion source (ebis) is used in atomic physics to produce highly charged ions by bombarding atoms with a powerful electron beam. its principle of operation is shared by the electron beam ion trap. ===electron capture ionization=== electron capture ionization (eci) is the ionization of a gas phase atom or molecule by attachment of an electron to create an ion of the form aââ¢. the reaction is :a + e^- \overset{m}{\to} a^- where the m over the arrow denotes that to conserve energy and momentum a third body is required (the molecularity of the reaction is three). electron capture can be used in conjunction with chemical ionization. an electron capture detector is used in some gas chromatography systems. ==chemical ionization== chemical ionization (ci) is a lower energy process than electron ionization because it involves ion/molecule reactions rather than electr
Accelerator_physics Ion_source Ions