• Title/Summary/Keyword: Ion Optics

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Theoretical Design of Ion Optics for Effective Ion Detection in Single Particle Mass Spectrometer (단일 입자 질량분석기의 효과적인 이온검출을 위한 이온계의 이론적인 설계)

  • Cho Sung-Woo;Lee Dong-Geun
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.30 no.7
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    • pp.638-645
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    • 2006
  • Recently, we reported that significant ion loss occurred prior to its detection in the conventional single particles mass spectrometry and more seriously the loss is ion-kinetic-energy-dependent. These lead to significant error in the measured chemical composition of nanoparticles. Here we attempted to design a novel ion optics that is capable of 100% detection of ions generated from single nanoparticle. Using a commercial software SIMION, we simulated the trajectories of ions launched at different speeds inside the previous single particle mass spectrometer We tested how affect changes in shape of repelling plate, adding Einzel lens, substitution of tube electrode between extraction and acceleration grids. As a results, we could find a best design by assembling the trials in the present condition.

Low Energy Ion-Surface Reactor

  • Choi, Won-Yong;Kang, Tae-Hee;Kang, Heon
    • Bulletin of the Korean Chemical Society
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    • v.11 no.4
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    • pp.290-296
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    • 1990
  • Ion-surface collision studies at low kinetic energies (1-100 eV) provide a unique opportunity for investigating reactions and collision dynamics at surfaces. A special ion optics system for generating an energy- and mass-selected ion beam of this energy is designed and constructed. An ultrahigh vacuum (UHV) reaction chamber, in which the ions generated from the beamline collide with a solid surface, is equipped with Auger electron spectroscopy (AES) and thermal desorption spectrometry (TDS) as in-situ surface analytical tools. The resulting beam from the system has the following characteristics : ion current of 5-50 nA, energy spread < 2eV, current stability within ${\pm}5%,$ and unit mass resolution below 20 amu. The performance of the instrument is illustrated with data representing the implantation behavior of $Ar^+$ into a graphite (0001) surface.

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Focused Electrospray Deposition for Matrix-assisted Laser Desorption/Ionization Mass Spectrometry

  • Jeong, Kyung-Hwan;Seo, Jong-Cheol;Yoon, Hye-Joo;Shin, Seung-Koo
    • Bulletin of the Korean Chemical Society
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    • v.31 no.8
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    • pp.2293-2298
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    • 2010
  • Focused electrospray (FES) deposition method is presented for matrix-assisted laser desorption/ionization (MALDI) mass spectrometry. FES ion optics consists of two cylindrical focusing electrodes capped with a truncated conical electrode through which an electrospray emitter passes along the cylindrical axis. A spray of charged droplets is focused onto a sample well on a MALDI target plate under atmospheric pressure. The shape and size distributions of matrix crystals are visualized by scanning electron microscope and the mass spectra are obtained by time-of-flight mass spectrometry. Angiotensin II, bradykinin, and substance P are used as test samples, while $\alpha$-cyano-4-hydroxycinnamic acid and dihydroxybenzoic acid are employed as matrices. FES of a sample/matrix mixture produces fine crystal grains on a 1-3 mm spot and reproducibly yields the mass spectra with little shot-to-shot and spot-to-spot variations. Although FES greatly stabilizes the signals, the space charge due to matrix ions limits the detection sensitivity of peptides. To avoid the space charge problem, we adopted a dual FES/FES mode, which separately deposits matrix and sample by FES in sequence. The dual FES/FES mode reaches the detection sensitivity of 0.88 amol, enabling ultrasensitive of peptides by homogeneously depositing matrix and sample under atmospheric pressure.