Micro Ion Mobility Spectrometry TechnologyJun Xu , William B. Whitten, and J. Michael Ramsey |
Ion mobility spectrometry (IMS) is capable of separating ionic species at atmosphere pressure and promises to have applications in detecting chemical warfare agents, explosives, and drugs. Miniaturization of such instruments can potentially provide "shirt pocket" devices that deliver information about ambient chemical species. We have been studying fundamental advantages and technical barriers in developing miniature ion mobility spectrometry. Our current miniature IMS demonstrates a feasible resolution and high sensitivity in separating ion mobility spectra produced by photoionization of NO, O2, and methyl-iodide. Broadening induced by Coulomb repulsion was determined to have a major effect on the resolution of the miniature device.
Miniaturization and Separation
Coulomb repulsion It is noted that the Coulomb contribution to the resolution depends on the total number of ions initially generated and thus should vary with the energy of the ionization laser pulse. We measured the resolution as a function of laser energy. The resolution was found to be lower at higher laser pulse energy. This effect was significantly larger at the lower bias voltage. These measurements suggest that Coulomb repulsion effect on resolution needs to be considered in developing miniature ion mobility spectrometry.
Future and Acknowledgement |
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