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Jae C. Schwartz - One of the best experts on this subject based on the ideXlab platform.

  • a two dimensional quadrupole ion trap mass spectrometer
    Journal of the American Society for Mass Spectrometry, 2002
    Co-Authors: Jae C. Schwartz, Michael W Senko, John E P Syka
    Abstract:

    The use of a linear or two-dimensional (2-D) quadrupole ion trap as a high performance mass spectrometer is demonstrated. Mass analysis is performed by ejecting ions out a slot in one of the rods using the mass selective Instability Mode of operation. Resonance ejection and excitation are utilized to enhance mass analysis and to allow isolation and activation of ions for MSn capability. Improved trapping efficiency and increased ion capacity are observed relative to a three-dimensional (3-D) ion trap with similar mass range. Mass resolution comparable to 3-D traps is readily achieved, including high resolution at slower scan rates, although adequate mechanical tolerance of the trap structure is a requirement. Additional advantages of 2-D over 3-D ion traps are also discussed and demonstrated.

  • High mass-resolution using a quadrupole ion-trap mass spectrometer
    Rapid Communications in Mass Spectrometry, 1991
    Co-Authors: Jon D. Williams, R. Graham Cooks, Jae C. Schwartz, Kathleen Cox, Raymond E. Kaiser, Simon J. Gaskell
    Abstract:

    Modifications have been made to the quadrupole ion-trap mass spectrometer (ITMS) to improve the resolution. An offset-digital-to-analog converter/attenuator network is used to slow down the scan rate in the mass-selective Instability Mode of operation with reasonance ejection. Attenuations of the scan rate by 200 to 700 times increase the resolution from 500 (with no attenuation) to 40 000 and 100 000 (full width at half maximum), respectively, for the [M + H]+ peak of substance p (m/z 1348). These improved resolutions are achieved in experiments which use resonance ejection to extend the mass-to-charge range.

  • High resolution on a quadrupole ion trap mass spectrometer
    Journal of the American Society for Mass Spectrometry, 1991
    Co-Authors: Jae C. Schwartz, John E P Syka, Ian Jardine
    Abstract:

    By using a modified ion trap mass spectrometer, resolution in excess of 30,000 (FWHM) at m I z 502 is demonstrated. The method of increasing resolution in the ion trap mass spectrometer operated in the mass-selective Instability Mode depends on decreasing the rate of scanning the primary radio frequency amplitude as well as using resonance ejection at the appropriate frequency and amplitude. A theoretical basis for the method is introduced.

John E P Syka - One of the best experts on this subject based on the ideXlab platform.

  • a two dimensional quadrupole ion trap mass spectrometer
    Journal of the American Society for Mass Spectrometry, 2002
    Co-Authors: Jae C. Schwartz, Michael W Senko, John E P Syka
    Abstract:

    The use of a linear or two-dimensional (2-D) quadrupole ion trap as a high performance mass spectrometer is demonstrated. Mass analysis is performed by ejecting ions out a slot in one of the rods using the mass selective Instability Mode of operation. Resonance ejection and excitation are utilized to enhance mass analysis and to allow isolation and activation of ions for MSn capability. Improved trapping efficiency and increased ion capacity are observed relative to a three-dimensional (3-D) ion trap with similar mass range. Mass resolution comparable to 3-D traps is readily achieved, including high resolution at slower scan rates, although adequate mechanical tolerance of the trap structure is a requirement. Additional advantages of 2-D over 3-D ion traps are also discussed and demonstrated.

  • High resolution on a quadrupole ion trap mass spectrometer
    Journal of the American Society for Mass Spectrometry, 1991
    Co-Authors: Jae C. Schwartz, John E P Syka, Ian Jardine
    Abstract:

    By using a modified ion trap mass spectrometer, resolution in excess of 30,000 (FWHM) at m I z 502 is demonstrated. The method of increasing resolution in the ion trap mass spectrometer operated in the mass-selective Instability Mode depends on decreasing the rate of scanning the primary radio frequency amplitude as well as using resonance ejection at the appropriate frequency and amplitude. A theoretical basis for the method is introduced.

Zou Zhiming - One of the best experts on this subject based on the ideXlab platform.

  • Dewetting of a pre-patterned thin polymer bilayer: influence of the Instability Mode
    RSC Advances, 2017
    Co-Authors: Zhengjian Chen, Zou Zhiming
    Abstract:

    In this paper, the influence of film thickness on the layer Instability Mode of a thin polymer bilayer (poly(methylmethacrylate) (PMMA)/polystyrene (PS)/Si substrate) has been investigated. The experimental results show that kinetic forces can greatly influence the Instability process of the thin polymer bilayer. In the case of PS-2.4K (Mw-PS = 2.4 kg mol−1), only the PS layer ruptures between the PMMA layer and the solid substrate and the dewetting is kinetically controlled. In the case of PS-31K (Mw-PS = 31 kg mol−1), the Instability of the polymer bilayer changes from a kinetically controlled one to a thermodynamically controlled one with the increase of PS film thickness. In the case of PS-97K (Mw-PS = 97 kg mol−1), only the PMMA layer ruptures on the PS layer and the dewetting process is a thermodynamically controlled one. Besides, the influence of the Instability Mode on the template-assisted dewetting process of the thin polymer bilayer also was studied. After annealing the pre-patterned bilayer, in the case of the kinetically controlled dewetting, the PMMA film bends to conform to the buried PS–PMMA interface and concave half cylinder grooves form during the dewetting process; however, in the case of the thermodynamically controlled dewetting, PMMA chains move to the top of cylinder stripes and obvious trenches are found after PMMA chains are etched. This proposes a simple method to obtain different surface structures by changing the Instability Mode of the thin polymer bilayer.

Ian Jardine - One of the best experts on this subject based on the ideXlab platform.

  • High resolution on a quadrupole ion trap mass spectrometer
    Journal of the American Society for Mass Spectrometry, 1991
    Co-Authors: Jae C. Schwartz, John E P Syka, Ian Jardine
    Abstract:

    By using a modified ion trap mass spectrometer, resolution in excess of 30,000 (FWHM) at m I z 502 is demonstrated. The method of increasing resolution in the ion trap mass spectrometer operated in the mass-selective Instability Mode depends on decreasing the rate of scanning the primary radio frequency amplitude as well as using resonance ejection at the appropriate frequency and amplitude. A theoretical basis for the method is introduced.

Tongfei Shi - One of the best experts on this subject based on the ideXlab platform.

  • Liquid–liquid interfacial slip induced layer Instability in a thin polymer bilayer
    Polymer, 2016
    Co-Authors: Huanhuan Zhang, Tongfei Shi
    Abstract:

    Abstract We investigate the influence of interfacial slip on the layer Instability of thin polymer bilayer (polymethylmethacrylate (PMMA)/polystyrene (PS)/solid substrate). In the case of the bilayer system with a high molecular weight (M w ) PMMA upper layer, it is found that the viscosity ratio of the two layers can greatly affect the Instability Modes of the polymer bilayer and there is a switchover of two different Instability Modes: (I) the dewetting of the PMMA upper layer on the PS under layer and (II) the dewetting of the PS under layer between the PMMA upper layer and the solid substrate. With the increase in the viscosity ratio between the PMMA upper layer and the PS under layer, the Instability Mode shifts from the Instability Mode I to the Instability Mode II. From our experimental results, it is found that the interfacial slip effect at the PMMA-PS interface is an important reason behind this switchover and the Instability of the polymer bilayer system becomes a kinetically controlled one. However, in the case of the bilayer system with a lower M w PMMA upper layer, the viscosity ratio of the two layers does not alter the Instability Mode of thin polymer bilayer and only the PMMA upper layer dewets on the PS under layers with different M w . The Instability of the polymer bilayer system is a thermodynamic controlled one.