# Photoelectron emission as an alternative electron impact ionization source for ion trap mass spectrometry

Author(s) Gamez, Gerardo, Zhu, Liang, Schmitz, Thomas A., Zenobi, Renato
Publication Type Journal Items, Publication Status: Published
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Title Photoelectron emission as an alternative electron impact ionization source for ion trap mass spectrometry
Author(s) Gamez, Gerardo
Zhu, Liang
Schmitz, Thomas A.
Zenobi, Renato
Journal or Series Title Analytical chemistry
Volume Number 80
Issue Number 17
Start Page 6791
End Page 6795
ISSN 0003-2700
1520-6882
Publisher American Chemical Society
Publication Place Washington, DC
Publication Date 2008
Abstract Electron impact ionization has several known advantages; however, heated filament electron sources have pressure limitations and their power consumption can be significant for certain applications, such as in field-portable instruments. Herein, we evaluate a VUV krypton lamp as an alternative source for ionization inside the ion trap of a mass spectrometer. The observed fragmentation patterns are more characteristic of electron impact ionization than photoionization. In addition, mass spectra of analytes with ionization potentials higher than the lamp's photon energy (10.6 eV) can be easily obtained. A photoelectron impact ionization mechanism is suggested by the observed data allowed by the work function of the ion trap electrodes (4.5 eV), which is well within the lamp's photon energy. In this case, the photoelectrons emitted at the surface of the ion trap end-cap electrode are accelerated by the applied rf field to the ring electrode. This allows the photoelectrons to gain sufficient energy to ionize compounds with high ionization potentials to yield mass spectra characteristic of electron impact. In this manner, electron impact ionization can be used in ion trap mass spectrometers at low powers and without the limitations imposed by elevated pressures on heated filaments.
DOI 10.1021/ac8007187
Additional Notes Received 11 April 2008, Accepted 27 June 2008, Publication Date (Web) 30 July 2008
Document Type Article
Publication Status Published
Language English
Assigned Organisational Unit(s) 03430
Organisational Unit(s)
NEBIS System Number 000005465
Source Database ID PP-41459
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@article{Gmz2008,
author = "Gamez, Gerardo and Zhu, Liang and Schmitz, Thomas A. and Zenobi, Renato",
title = "{P}hotoelectron emission as an alternative electron impact ionization source for ion trap mass spectrometry",
journal = "Analytical chemistry",
year = 2008,
volume = "80",
number = "17",
pages = "6791--6795",
}


E-Citations record created: Thu, 01 Apr 2010, 23:01:36 CET