Fragment ion



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Fragment ion 

  • Fragment ion 

  • An electrically charged dissociation product of an ionic fragmentation. Such an ion may fragmentate further to produce other electrically charged molecular or atomic moieties of successively lower formula weight.

  • Fragmentation  Break Of Covalent Bond











Typical reagent gases (ex. CH4, isobutane, or NH3) are present in a millionfold excess with respect to the analyte.

  • Typical reagent gases (ex. CH4, isobutane, or NH3) are present in a millionfold excess with respect to the analyte.

  • Analyte is ionized by ion-molecule chemical reactions:

    • Primary Ion Formation:
      • CH4 + e-  CH4+ + 2e-
    • Secondary Reagent Ions:
    • CH4 + CH4+  CH5+ + CH3
    • CH4 + CH3+  C2H5+ + H2
    • Product Ion Formation:
      • M + CH5+  CH4 + [M + H] + (protonation)
      • AH + CH3+  CH4 + A+ (H− abstraction)
      • M + CH5+  [M+ CH5] + (adduct formation)
      • A + CH4+  CH4 + A+ (charge exchange)


Material to be analyzed is mixed with a non-volatile chemical protection environment called a matrix

  • Material to be analyzed is mixed with a non-volatile chemical protection environment called a matrix

  • This is bombarded under vacuum with a high energy (4 – 10 keV) beam of atoms.

  • Atoms are typically an inert gas (Ar or Xe)





















































In this device, positive ions strike a conversion cathode liberating electrons which are then accelerated and multiplied’ via a series of up to twenty dynodes. This type of detector is extremely sensitive, having a gain of up to 108. Aluminium-based dynodes have improved performances of the traditional materials (Cu/Be alloys) which age rather badly in the residual atmosphere of the spectrometers, or during non working periods (returning to atmospheric pressure).

  • In this device, positive ions strike a conversion cathode liberating electrons which are then accelerated and multiplied’ via a series of up to twenty dynodes. This type of detector is extremely sensitive, having a gain of up to 108. Aluminium-based dynodes have improved performances of the traditional materials (Cu/Be alloys) which age rather badly in the residual atmosphere of the spectrometers, or during non working periods (returning to atmospheric pressure).





The ions are directed towards a collector whose entrance, in the form of a horn, is made of a lead doped glass with which acts as the conversion cathode. The ejected electrons are attracted towards a positive electrode and their collisions against the internal walls give rise to multiplication, as with the separated dynodes. The assembly is usually mounted off-axis to avoid the impact of neutral species as well as photons emitted by the filament, equally susceptible to the removal of the electrons.

  • The ions are directed towards a collector whose entrance, in the form of a horn, is made of a lead doped glass with which acts as the conversion cathode. The ejected electrons are attracted towards a positive electrode and their collisions against the internal walls give rise to multiplication, as with the separated dynodes. The assembly is usually mounted off-axis to avoid the impact of neutral species as well as photons emitted by the filament, equally susceptible to the removal of the electrons.





They consist of the union of a large number microchanneltrons arranged like honeycombs. This resembles an electronic version of a photographic plate. Each individual detector is formed from a portion of microtube (25m diameter) whose interior is coated by a semiconductor material acting as a continuous dynode. This system preserves the spatial resolution of the input charged ions.

  • They consist of the union of a large number microchanneltrons arranged like honeycombs. This resembles an electronic version of a photographic plate. Each individual detector is formed from a portion of microtube (25m diameter) whose interior is coated by a semiconductor material acting as a continuous dynode. This system preserves the spatial resolution of the input charged ions.







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