ELECTRON IONIZATION Meaning and
Definition
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Electron ionization, also known as electron impact ionization, is a process that occurs in mass spectrometry and gas-phase chemistry. It is a method used to produce molecular ions or fragments from gaseous molecules.
In electron ionization, a high-energy electron beam is directed towards a sample molecule, typically in the gas phase. When the electrons collide with the molecule, they transfer energy to the molecule, causing it to become ionized. This process typically removes one electron from the molecule, generating a positively charged molecular ion (M+).
The produced molecular ions are then accelerated in an electric field and their masses are analyzed using a mass spectrometer. By measuring the mass-to-charge ratio (m/z), it is possible to determine the molecular weight and identify the molecular structure of the sample molecule. The fragmentation pattern obtained from electron ionization is often characteristic and can be used for structural analysis.
The electron ionization process requires a relatively high energy electron beam to cause ionization, which may result in the fragmentation of the molecule. This fragmentation can be advantageous as it provides information about the molecular structure, but also leads to the formation of fragment ions that can complicate mass spectral interpretation.
Overall, electron ionization is a widely used technique in mass spectrometry for the identification, quantification, and characterization of organic and inorganic compounds. It is valuable in various fields including pharmaceuticals, environmental analysis, forensics, and materials science.
Etymology of ELECTRON IONIZATION
The etymology of the word "electron ionization" can be broken down as follows:
- Electron: The term "electron" originates from the Greek word "ēlektron", meaning "amber". The name was given by physicist George Johnstone Stoney in 1891 when he proposed the existence of a fundamental unit of negative electric charge.
- Ionization: The term "ionization" comes from the word "ion", which was derived from the Greek word "iōn", meaning "that which goes". It was introduced by physicist Michael Faraday in 1834 to describe charged particles formed during chemical reactions. The suffix "-ization" means "the process of", so "ionization" refers to the process of generating ions.
- Therefore, "electron ionization" refers to the process of generating ions by the interaction of electrons with atoms or molecules.
