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Progress In The Development Of An Infrared Ion Beam Spectrometer

Progress In The Development Of An Infrared Ion Beam Spectrometer. Outline. Why molecular ion beam First generation SCRIBES instrument. Improvements Development of the second generation SCRIBES Prospects. S ensitive C old R esolved I on BE am S pectrometer. High resolution spectroscopy

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Progress In The Development Of An Infrared Ion Beam Spectrometer

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  1. Progress In The Development Of An Infrared Ion Beam Spectrometer

  2. Outline • Why molecular ion beam • First generation SCRIBES instrument • Improvements • Development of the second generation SCRIBES • Prospects Sensitive Cold Resolved Ion BEam Spectrometer

  3. High resolution spectroscopy • Fingerprint for molecular ions Δω depends on √1/Ufloat voltage Andrew Mills, WH02 at 2:05pm Why Use Molecular Ion Beam? • Why molecular ions • Astrochemistry • Combustion • Carbocation chemistry • Fundamental insterest • Why fast ion beam • Kinematic compression

  4. First Generation SCRIBES Instrument Electron Multiplier • Modular • Low ion beam current • Overlap of the laser Anode • Development of TOF-MS Cathode Iris Pulser Plate Ion Optics Ringdown Mirrors InSb Ion Optics Drift Region Quadrupoles Modeled after Saykally’s instrument (Saykally et al. J. Chem. Phys.1989, 90 (8), 3893-3894)

  5. Source Second Generation SCRIBES • Modular instrumentation • High ion beam current • Improved ion optics • Differential pumping

  6. Anode Cathode Precursor gas Fused Silica Ion Sources • Considerations for the test application • High ion density • Fast ion beam without a big energy spread • Low maintenance • Supersonic source • Cold cathode discharge source • Rotationally cold ions • Continuous source • Modular

  7. Cathode 3.5 kV Anode 7.5 kV Source Extraction plate Ground N2 plasma Uncooled Cold Cathode Source with N2 Plasma ISource = 30 µA IBeam = 10 µA IOverlap = 1.5 µA

  8. Einzel Lens Side view Frontal view Ion Optics

  9. Laser path Neutrals Ions only V+ V- Cavity Region 3 mm 3 mm

  10. Output Input Quadrupoles +V -V Collimated beam +V -V Diverging beam

  11. Output parallel beam Input focused beam Asymmetrical Deflector Plates (+)V (-)V

  12. Time-of-Flight Mass Spectrometer Mass Selecting Region • Identity of the masses • Beam energy • Beam energy spread • Characterization method • TOF mass spectrometer

  13. Laser Collision Cell CO2 gas at 30 mTorr Ringdown mirror

  14. Mass Spectrometer

  15. Mass Spectrum of N2 Plasma Ion beam energy = 3580 V ± 10 V Power supply output = 3574 V

  16. Velocity modulated cavity enhanced spectroscopy cw-Cavity ringdown spectroscopy Ion modulated cavity ringdown spectroscopy 1st Generation SCRIBES 2st Generation SCRIBES Growth of SCRIBES Supersonic source H3+ band (fundamental) Test N2+ Meinel lines DFG laser

  17. Acknowledgement • McCall Group • Funding

  18. Questions?

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