Selected ion flow tube: Difference between revisions

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The '''selected ion flow tube''', '''SIFT''', technique is a fast flow tube / ion swarm method for the study of the reactions of ions (positive or negative) with atoms and molecules under truly thermalised conditions over a wide range of temperature. It has been extensively used to study ion???????????????molecule kinetics. Its application to atmospheric and interstellar ion chemistry over a 20-year period has been crucial to the advancement and understanding of these interesting topics. Recently it has been developed as a very sensitive analytical technique '''SIFT-MS selected ion flow tube mass spectrometry''' for the quantification of trace gases in air and in human breath down to the ppb level and in real time using [[chemical ionisation]].
{{Final
 
|acronym=([[SIFT]])
===Instrumentation===
|def=Device in which ''[[m/z]]'' selected ions are entrained in an inert carrier gas and subsequently undergo [[ion/molecule reaction]]s with molecules introduced into the gas flow.
 
|rel=[[drift tube]]
'''The SIFT apparatus'''
|ref=N. G. Adams, D. Smith. Int. J. Mass Spectrom. Ion Phys. 21, 349 (1976). (http://dx.doi.org/10.1016/0020-7381(76)80133-7 )
 
}}
In the SIFT apparatus the ions are created in an ion source which is external to the flow tube. The ions are then extracted from the ion source, selected according to their mass-to-charge ratio using a quadrupole mass filter and injected into a flowing carrier gas (usually helium at a pressure of 0.5 Torr) via a small orifice ( ~1 mm diameter).
 
The carrier gas is inhibited from entering the quadrupole mass filter chamber by injecting it into the flow tube through a Venturi-type inlet at near-supersonic velocity in a direction away from the orifice. In this way a swarm of a single ion species thermalised at the same temperature as the carrier gas are convected along the flow tube ( ~1 m long), sampled by a downstream pinhole orifice, mass analysed and counted by a differentially-pumped quadrupole mass spectrometer system.  
 
 
== Related Terms ==
 
[[Drift Tube]]
 
 
== External Links ==
 
[http://www.jh-inst.cas.cz/~spanel/sift.htm Heyrovsk???????????? Institute of Physical Chemistry]
 
[http://www.chem.yorku.ca/profs/bohme/research/et__MAIN.html York University]
 
[[Category:Ionization]]
[[Category:Ionization]]
[[Category:Reactions]]
[[Category:Reactions]]

Latest revision as of 13:16, 8 January 2014

IUPAC RECOMMENDATIONS 2013
Selected ion flow tube (SIFT)
Device in which m/z selected ions are entrained in an inert carrier gas and subsequently undergo ion/molecule reactions with molecules introduced into the gas flow.
Related Term(s): drift tube
Reference(s):

N. G. Adams, D. Smith. Int. J. Mass Spectrom. Ion Phys. 21, 349 (1976). (http://dx.doi.org/10.1016/0020-7381(76)80133-7 )

From Definitions of Terms Relating to Mass Spectrometry (IUPAC Recommendations 2013); DOI: 10.1351/PAC-REC-06-04-06 © IUPAC 2013.

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