Gas Phase Ionization by Energetic Electrons

Besides some rare experimental setups the mass analyzer of any mass spectrometer can only handle charged species, i.e., ions that have been created from atoms or molecules, occasionally also from radicals, zwitterions or clusters. It is the task of the ion source to perform this cmcial step and there is a wide range of ionization methods in use to achieve this goal for the whole variety of analytes. 

Mass Spectrometry, 2nded., DOI 10.1007/978-3-642-10711-5 2, Springer-Verlag Berlin Heidelberg 2011 

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