Editing Electron ionization (section)

=== Use with time-of-flight mass spectrometry ===
The electron ionization time of flight mass spectroscopy (EI-TOF MS) is well suited for analytical and basic chemical physics studies. EI-TOF MS is used to find ionization potentials of molecules and [[Radical (chemistry)|radicals]], as well as [[Bond-dissociation energy|bond dissociation energies]] for ions and neutral molecules. Another use of this method is to study about negative ion chemistry and physics. [[Autodetachment|Autodetachment lifetimes]], [[Metastability|metastable]] dissociation, [[Electron transfer|Rydberg electron transfer reactions]] and field detachment, [[Sulfur hexafluoride|SF6]] scavenger method for detecting temporary negative ion states, and many others have all been discovered using this technique. In this method the field free ionization region allows for high precision in the electron energy and also high electron energy resolution. Measuring the electric fields down the ion flight tube determines autodetachment and metastable decomposition as well as field detachment of weakly bound negative ions.<ref>{{Cite journal|last1=Mirsaleh-Kohan|first1=Nasrin|last2=Robertson|first2=Wesley D.|last3=Compton|first3=Robert N.|date=2008-05-01|title=Electron ionization time-of-flight mass spectrometry: Historical review and current applications|journal=Mass Spectrometry Reviews|language=en|volume=27|issue=3|pages=237–285|doi=10.1002/mas.20162|issn=1098-2787|pmid=18320595|bibcode=2008MSRv...27..237M}}</ref>

The first description of an electron ionization orthogonal-acceleration TOF MS (EI oa-TOFMS) was in 1989. By using "orthogonal-acceleration" with the EI ion source the resolving power and sensitivity was increased. One of the key advantage of oa-TOFMS with EI sources is for deployment with gas chromatographic (GC) inlet systems, which allows chromatographic separation of [[volatile organic compound]]s to proceed at high speed.<ref>{{Cite journal|last1=Guilhaus|first1=M.|last2=Selby|first2=D.|last3=Mlynski|first3=V.|date=2000-01-01|title=Orthogonal acceleration time-of-flight mass spectrometry|url=http://onlinelibrary.wiley.com/doi/10.1002/(SICI)1098-2787(2000)19:23.0.CO;2-E/abstract|journal=Mass Spectrometry Reviews|language=en|volume=19|issue=2|pages=65–107|doi=10.1002/(SICI)1098-2787(2000)19:2<65::AID-MAS1>3.0.CO;2-E|pmid=10795088|issn=1098-2787|bibcode=2000MSRv...19...65G|url-access=subscription}}{{Dead link|date=December 2019 |bot=InternetArchiveBot |fix-attempted=yes}}</ref>