Field-Emission Cold-Cathode EI Source for a Microscale Ion Trap Mass Spectrometer

Kornienko, Oleg; Pt, Reilly; Wb, Whitten; Jm, Ramsey

doi:10.1021/ac990962s

Cited by 38 publications

(31 citation statements)

References 11 publications

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“…Therefore field emission cold cathodes which nominally operate at room temperature are attractive for some electron-impact applications. Kornienko et al 4 evaluated a cold cathode electronimpact ion source made from an array of diamond-coated silicon whiskers for application in an ion trap mass spectrometer. Others have reported traditional vacuum ion gauges utilizing carbon nanotubes 5,6 ͑CNTs͒ and molybdenum tips 7 as the electron source.…”

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confidence: 99%

On-chip electron-impact ion source using carbon nanotube field emitters

Bower

Gilchrist

Piascik

et al. 2007

Applied Physics Letters

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A lateral on-chip electron-impact ion source utilizing a carbon nanotube field emission electron source was fabricated and characterized. The device consists of a cathode with aligned carbon nanotubes, a control grid, and an ion collector electrode. The electron-impact ionization of He, Ar, and Xe was studied as a function of field emission current and pressure. The ion current was linear with respect to gas pressure from 10−4to10−1Torr. The device can operate as a vacuum ion gauge with a sensitivity of approximately 1Torr−1. Ion currents in excess of 1μA were generated.

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confidence: 99%

On-chip electron-impact ion source using carbon nanotube field emitters

Bower

Gilchrist

Piascik

et al. 2007

Applied Physics Letters

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“…In addition, a variety of field emitters have been microfabricated for miniaturized mass spectrometers. These include cold-cathodes and their arrays (Felter, 1999;Kornienko et al, 2000), a ring emitter (Van Amerom et al, 2008), carbon nanopearls (Mouton et al, 2008), carbon nanoparticles (Yoon et al, 2007), carbon nanofiber arrays (Chen et al, 2007), and carbon nanotubes (Getty et al, 2007. The main advantage of field emitters over hot filaments is their better tolerance to the high pressure inside the ion source.…”

Section: Miniaturized Ion Sources For Gaseous Samplesmentioning

confidence: 99%

Microchip technology in mass spectrometry

Sikanen

Franssila

Kauppila

et al. 2009

Mass Spectrom. Rev.

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Microfabrication of analytical devices is currently of growing interest and many microfabricated instruments have also entered the field of mass spectrometry (MS). Various (atmospheric pressure) ion sources as well as mass analyzers have been developed exploiting microfabrication techniques. The most common approach thus far has been the miniaturization of the electrospray ion source and its integration with various separation and sampling units. Other ionization techniques, mainly atmospheric pressure chemical ionization and photoionization, have also been subject to miniaturization, though they have not attracted as much attention. Likewise, all common types of mass analyzers have been realized by microfabrication and, in most cases, successfully applied to MS analysis in conjunction with on-chip ionization. This review summarizes the latest achievements in the field of microfabricated ion sources and mass analyzers. Representative applications are reviewed focusing on the development of fully microfabricated systems where ion sources or analyzers are integrated with microfluidic separation devices or microfabricated pums and detectors, respectively. Also the main microfabrication methods, with their possibilities and constraints, are briefly discussed together with the most commonly used materials.

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“…Many miniaturized ion sources use EI and have CNT field emitters as the cathode, [3][4][5][6][7][8] or other cathode material.…”

Section: B Miniaturization Of Ion Sourcesmentioning

confidence: 99%

Analysis of 3-panel and 4-panel microscale ionization sources

Natarajan

Piascik

Gilchrist

et al. 2010

Journal of Applied Physics

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Two designs of a microscale electron ionization ͑EI͒ source are analyzed herein: a 3-panel design and a 4-panel design. Devices were fabricated using microelectromechanical systems technology. Field emission from carbon nanotube provided the electrons for the EI source. Ion currents were measured for helium, nitrogen, and xenon at pressures ranging from 10 −4 to 0.1 Torr. A comparison of the performance of both designs is presented. The 4-panel microion source showed a 10ϫ improvement in performance compared to the 3-panel device. An analysis of the various factors affecting the performance of the microion sources is also presented. SIMION, an electron and ion optics software, was coupled with experimental measurements to analyze the ion current results. The electron current contributing to ionization and the ion collection efficiency are believed to be the primary factors responsible for the higher efficiency of the 4-panel microion source. Other improvements in device design that could lead to higher ion source efficiency in the future are also discussed. These microscale ion sources are expected to find application as stand alone ion sources as well as in miniature mass spectrometers. © 2010 American Institute of Physics. ͓doi:10.1063/1.3429220͔ I. APPLICATIONS AND LITERATURE REVIEW OF MICROSCALE ION SOURCES A. Introduction to ionization sourcesIon sources are important scientific devices that find application in a variety of areas. They are used in particle accelerators, ion implantation systems for the semiconductor industry, semiconductor processes such as reactive ion etching, giant neutral beam injectors in experimental fusion reactor devices, and in analytical instruments such as mass spectrometers. 1Gas phase ionization techniques include electron ionization ͑EI͒, field ionization, and chemical ͑or charge transfer͒ ionization. Electron impact ionization or electron bombardment ionization is the process in which an electron with suitable energy collides with a neutral atom or molecule resulting in the formation of an ion and an electron. In field ionization, an electron is removed by tunneling from the molecule in the presence of a strong electric field, creating an ion. Field ionization tends to result in fewer fragmentation events than does EI. Chemical ionization uses a reagent gas, such as methane. The reagent gas is ionized using an EI source, for example, and then reacted with the analyte molecules, ionizing them in a lower energy state, also resulting in less fragmentation than in EI.Liquid and solid phase ionization techniques are most commonly used for mass spectroscopy. Liquid phase techniques include atmospheric pressure chemical ionization, field desorption, and electrospray ionization ͑ESI͒. These techniques require the analyte compound to be nebulized into the gas phase and the solvent removed through a series of stages of increasing vacuum ͑typically atmosphere to 10 −6 Torr or greater͒ as the ions travel into the mass spectrometer. Solid phase techniques include matrix-assisted laser des...

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Field-Emission Cold-Cathode EI Source for a Microscale Ion Trap Mass Spectrometer

Cited by 38 publications

References 11 publications

On-chip electron-impact ion source using carbon nanotube field emitters

On-chip electron-impact ion source using carbon nanotube field emitters

Microchip technology in mass spectrometry

Analysis of 3-panel and 4-panel microscale ionization sources

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