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Robert J. Cotter - One of the best experts on this subject based on the ideXlab platform.

  • Ideal velocity focusing in a Reflectron time-of-flight mass spectrometer.
    Journal of the American Society for Mass Spectrometry, 1999
    Co-Authors: Vladimir M. Doroshenko, Robert J. Cotter
    Abstract:

    A single-stage ion mirror in a time-of-flight (TOF) mass spectrometer (MS) can perform first order velocity focusing of ions initially located at a start focal plane while second order velocity focusing can be achieved using a double-stage Reflectron. The situation is quite different when an ion source extraction field is taken into account. In this case which is common in any practical matrix-assisted laser desorption/ionization (MALDI) TOF-MS a single-stage Reflectron, for example, cannot perform velocity focusing at all. In this paper an exact, analytic solution for an electric field inside a one-dimensional Reflectron has been found to achieve universal temporal focusing of ions having an initial velocity distribution. The general solution is valid for arbitrary electric field distributions in the upstream (from the ion source to the Reflectron) and downstream (from the Reflectron to an ion detector) regions and in a decelerating part of the Reflectron of a Reflectron TOF mass spectrometer. The results obtained are especially useful for designing MALDI Reflectron TOF mass spectrometers in which the initial velocity distribution of MALDI ions is the major limiting factor for achieving high mass resolution. Using analytical expressions obtained for an arbitrary case, convenient working formulas are derived for the case of a Reflectron TOF-MS with a dual-stage extraction ion source. The special case of a MALDI Reflectron TOF-MS with an ion source having a low acceleration voltage (or large extraction region) is considered. The formulas derived correct the effect of the acceleration regions in a MALDI ion source and after the Reflectron before detecting ions.

  • Sequencing peptides without scanning the Reflectron: Post-source decay with a curved-field Reflectron time-of-flight mass spectrometer
    Rapid communications in mass spectrometry : RCM, 1995
    Co-Authors: Marcela M. Cordero, Timothy J. Cornish, Robert J. Cotter, Ihor. Lys
    Abstract:

    A time-of-flight mass spectrometer has been developed using a Reflectron in which the voltages placed on the lens elements correspond to a function describing the arc of a circle. This curved-field Reflectron enables acquisition of focused product-ion mass spectra at a single Reflectron voltage. In this paper, we present results from this instrument for the amino acid sequencing of several peptides and describe the method of mass calibration.

  • a curved field Reflectron for improved energy focusing of product ions in time of flight mass spectrometry
    Rapid Communications in Mass Spectrometry, 1993
    Co-Authors: Timothy J. Cornish, Robert J. Cotter
    Abstract:

    A new type of curved-field Reflectron has been developed for the energy focusing of ions formed after initial acceleration in time-of-flight (TOF) mass spectrometers. These include ions generated in the dissociation region of a tandem TOF, as well as metastable decay products formed in the field-free drift region prior to their reflection. Unlike conventional linear-field Reflectrons, which focus product ions to different focal lengths that are proportional to the mass (energy) of the fragment, the new curved-field Reflectron energy focuses all ions to within a small region near the exit of the Reflectron. Thus, the collection of resolved fragment peaks is possible without scanning or stepping the potential gradient of the Reflectron, enabling faster acquisition of the production spectrum and, more importantly, true multiplex recording of the spectra from each ionization event. Theoretical considerations of the design are discussed along with an evaluation of collision-induced dissociation data, demonstrating the performance of the new Reflectron in a tandem TOF instrument.

  • A curved‐field Reflectron for improved energy focusing of product ions in time‐of‐flight mass spectrometry
    Rapid communications in mass spectrometry : RCM, 1993
    Co-Authors: Timothy J. Cornish, Robert J. Cotter
    Abstract:

    A new type of curved-field Reflectron has been developed for the energy focusing of ions formed after initial acceleration in time-of-flight (TOF) mass spectrometers. These include ions generated in the dissociation region of a tandem TOF, as well as metastable decay products formed in the field-free drift region prior to their reflection. Unlike conventional linear-field Reflectrons, which focus product ions to different focal lengths that are proportional to the mass (energy) of the fragment, the new curved-field Reflectron energy focuses all ions to within a small region near the exit of the Reflectron. Thus, the collection of resolved fragment peaks is possible without scanning or stepping the potential gradient of the Reflectron, enabling faster acquisition of the production spectrum and, more importantly, true multiplex recording of the spectra from each ionization event. Theoretical considerations of the design are discussed along with an evaluation of collision-induced dissociation data, demonstrating the performance of the new Reflectron in a tandem TOF instrument.

Timothy J. Cornish - One of the best experts on this subject based on the ideXlab platform.

  • Sequencing peptides without scanning the Reflectron: Post-source decay with a curved-field Reflectron time-of-flight mass spectrometer
    Rapid communications in mass spectrometry : RCM, 1995
    Co-Authors: Marcela M. Cordero, Timothy J. Cornish, Robert J. Cotter, Ihor. Lys
    Abstract:

    A time-of-flight mass spectrometer has been developed using a Reflectron in which the voltages placed on the lens elements correspond to a function describing the arc of a circle. This curved-field Reflectron enables acquisition of focused product-ion mass spectra at a single Reflectron voltage. In this paper, we present results from this instrument for the amino acid sequencing of several peptides and describe the method of mass calibration.

  • a curved field Reflectron for improved energy focusing of product ions in time of flight mass spectrometry
    Rapid Communications in Mass Spectrometry, 1993
    Co-Authors: Timothy J. Cornish, Robert J. Cotter
    Abstract:

    A new type of curved-field Reflectron has been developed for the energy focusing of ions formed after initial acceleration in time-of-flight (TOF) mass spectrometers. These include ions generated in the dissociation region of a tandem TOF, as well as metastable decay products formed in the field-free drift region prior to their reflection. Unlike conventional linear-field Reflectrons, which focus product ions to different focal lengths that are proportional to the mass (energy) of the fragment, the new curved-field Reflectron energy focuses all ions to within a small region near the exit of the Reflectron. Thus, the collection of resolved fragment peaks is possible without scanning or stepping the potential gradient of the Reflectron, enabling faster acquisition of the production spectrum and, more importantly, true multiplex recording of the spectra from each ionization event. Theoretical considerations of the design are discussed along with an evaluation of collision-induced dissociation data, demonstrating the performance of the new Reflectron in a tandem TOF instrument.

  • A curved‐field Reflectron for improved energy focusing of product ions in time‐of‐flight mass spectrometry
    Rapid communications in mass spectrometry : RCM, 1993
    Co-Authors: Timothy J. Cornish, Robert J. Cotter
    Abstract:

    A new type of curved-field Reflectron has been developed for the energy focusing of ions formed after initial acceleration in time-of-flight (TOF) mass spectrometers. These include ions generated in the dissociation region of a tandem TOF, as well as metastable decay products formed in the field-free drift region prior to their reflection. Unlike conventional linear-field Reflectrons, which focus product ions to different focal lengths that are proportional to the mass (energy) of the fragment, the new curved-field Reflectron energy focuses all ions to within a small region near the exit of the Reflectron. Thus, the collection of resolved fragment peaks is possible without scanning or stepping the potential gradient of the Reflectron, enabling faster acquisition of the production spectrum and, more importantly, true multiplex recording of the spectra from each ionization event. Theoretical considerations of the design are discussed along with an evaluation of collision-induced dissociation data, demonstrating the performance of the new Reflectron in a tandem TOF instrument.

Ravi P. Singhal - One of the best experts on this subject based on the ideXlab platform.

  • A tandem Reflectron time‐of‐flight mass spectrometer for the investigation of laser photofragmentation of molecular ions
    Rapid Communications in Mass Spectrometry, 1995
    Co-Authors: W. J. Jia, Kenneth W. D. Ledingham, C. T. J. Scott, C. Kosmidis, Ravi P. Singhal
    Abstract:

    A tandem Reflectron time-of-flight mass spectrometer has been constructed for the investigation of laser photofragmentation of selected molecular ions. Ions are generated by an ablation laser and attracted by ion optics into the field-free flight region of a Reflectron time-of-flight mass spectrometer. Laser photofragmentation of selected molecular ions takes place at the turn-around point of ions in the Reflectron. Fragmentation mass calibration, parent ion selection, ion collection effects, Reflectron field effects and the mass resolution of this tandem Reflectron time-of-flight mass spectrometer are described. Furthermore it is shown that laser parameters may be used to control the fragmentation pattern.

Christie G. Enke - One of the best experts on this subject based on the ideXlab platform.

  • Method for the design of broad energy range focusing Reflectrons
    Journal of the American Society for Mass Spectrometry, 1996
    Co-Authors: Paul R. Vlasak, Douglas J. Beussman, Christie G. Enke
    Abstract:

    A novel method for the design of reflections capable of focusing large kinetic energy ranges is presented. The design method itself is a numerical approach that provides a geometrically flexible alternative to traditional analytical design solutions. This design method has been used to produce a Reflectron that provides unit mass resolution for product spectra in a tandem Reflectron time-of-flight (TOF) mass spectrometer despite a kinetic energy range of 1950–2700 eV. In this application, the systematic progression of Reflectron design results in a practical, nonlinear field Reflectron with the use of only two grids. Design improvements are proposed for more flexible systems, although geometric constraints in the current instrument limit their experimental evaluation.

W. J. Jia - One of the best experts on this subject based on the ideXlab platform.

  • A tandem Reflectron time‐of‐flight mass spectrometer for the investigation of laser photofragmentation of molecular ions
    Rapid Communications in Mass Spectrometry, 1995
    Co-Authors: W. J. Jia, Kenneth W. D. Ledingham, C. T. J. Scott, C. Kosmidis, Ravi P. Singhal
    Abstract:

    A tandem Reflectron time-of-flight mass spectrometer has been constructed for the investigation of laser photofragmentation of selected molecular ions. Ions are generated by an ablation laser and attracted by ion optics into the field-free flight region of a Reflectron time-of-flight mass spectrometer. Laser photofragmentation of selected molecular ions takes place at the turn-around point of ions in the Reflectron. Fragmentation mass calibration, parent ion selection, ion collection effects, Reflectron field effects and the mass resolution of this tandem Reflectron time-of-flight mass spectrometer are described. Furthermore it is shown that laser parameters may be used to control the fragmentation pattern.