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    Please use this identifier to cite or link to this item: http://tkuir.lib.tku.edu.tw:8080/dspace/handle/987654321/61577

    Title: Effects of collisional cooling on ion detection in a quadrupole ion trap mass spectrometer.
    Authors: Wu, H. F.;吳慧芬;Brodbelt, J. S.
    Contributors: 淡江大學化學學系
    Keywords: collisional cooling;collision-activated dissociation;ion detection
    Date: 1992-05-01
    Issue Date: 2011-10-15 23:18:26 (UTC+8)
    Abstract: The effects of collisional cooling on the storage and detection of ions in a quadrupole ion trap mass spectrometer are examined. Four parameters that affect the storage of ions are evaluated: the pressure of the buffer gas: the qz value which establishes the ion trapping environment; the cooling time during which ions may collapse to the center of the trap; and the supplementary a.c. voltage used to kinetically excite selected ions. The ion trap may be operated effectively at a low helium pressure (0.1 mTorr) if a sufficient delay period is added to allow the diffuse ion cloud to collapse to the center of the trap prior to detection. For a typical experiment, this modified operation at low pressures involves allowing the ions to undergo approximately 30–100 collisions (i.e. in a ≈30 ms interval at 0.1 mTorr). At low helium pressures (≈0.1 mTorr), more ions may be trapped at higher qz values. Collision-activated dissociation (CAD) at low helium pressures indicates that the average internal energy deposition is higher, and sensitivity is not lost, if a collisional cooling delay is added. This latter result potentially has great analytical relevance for CAD of biomolecules which require greater internal energy deposition to induce fragmentation.
    Relation: International journal of mass spectrometry and ion processes 115, pp.67-81
    DOI: 10.1016/0168-1176(92)85032-U
    Appears in Collections:[Graduate Institute & Department of Chemistry] Journal Article

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