Claims
- 1. A time-of-flight direct recoil ion scattering spectrometer, comprising:
- means for producing a paraxial beam of ions;
- means for pulsing said beam of ions, said pulsing means operative to dynamically adjust the interval between successive beam pulses in accordance with the combination of ion beam mass and energy to maximize repetition rate consistent with resolved data separation, said means for pulsing comprising a plurality of pulsed deflection plates separated from each other by an ion drift space for removing ions with laterally directed velocities;
- means for detecting particles emitted from a sample bombarded by said pulsed beam of ions; and
- means for providing differential pumping of an incoming ion beam path and an outgoing beam path of said spectrometer.
- 2. The spectrometer as defined in claim 1 wherein said pulsed deflection plates are coupled to means for applying a different voltage to different ones of said pulsed deflection plates.
- 3. The spectrometer as defined in claim 2 wherein said detector comprises a channeltron multiplier.
- 4. The spectrometer as defined in claim 3 wherein said channeltron multiplier comprises at least one smaller area detector and a segmented anode collector.
- 5. The spectrometer as defined in claim 2 wherein said detector comprises at least one detector disposed for detecting backscattered ones of said particles emitted from said sample.
- 6. The spectrometer as defined in claim 5 further including a detector disposed for detecting forward scattered ones of said particles emitted from said sample.
- 7. The spectrometer as defined in claim 6 further including a segmented anode collector.
- 8. The spectrometer as defined in claim 1 wherein said pulsing means includes means for directing signal events per ion beam pulse of consecutive signal events to separate data accumulation means.
- 9. The spectrometer as defined in claim 8 further including means for processing said consecutive signal events by adjusting time scale of each spectrum.
- 10. The spectrometer as defined in claim 1 wherein said differential pumping means includes a small aperture at the entrance to said means for detecting particles.
- 11. A method of performing time of flight direct recoil ion scattering spectrometry on a sample in a spectrometer, comprising the steps of:
- producing a pulsed paraxial beam of ions and further including the steps of dynamically adjusting at least one of the interval between successive beam pulses and beam width, said paraxial beam of ions being transmitted through apertures of a plurality of deflection plates by selected timed removal of deflection voltages applied to said deflection plates;
- detecting particles emitted from a sample bombarded by said pulsed beam of ions; and
- providing differential pumping of an incoming ion beam path and an outgoing beam path of said spectrometer.
- 12. The method as defined in claim 11 further including the step of aligning a sample area for analysis by said beam of ions by casting a bright pinpoint of light from a light source located on the detector axis onto an identifiable area of the sample to be examined.
- 13. The method as defined in claim 11 wherein said spectrometer includes an ion deflection region and deflection plates running the entire length of said ion deflection region thereby avoiding introduction of longitudinal velocity components to said ion beam.
- 14. The method as defined in claim 13 further including the step of forming a well-defined beam spot using ion beam focus means.
- 15. The method as defined in claim 14 wherein the beam spot size ranges upward from 1 micron in diameter.
- 16. The method as defined in claim 14 wherein said step of detecting particles includes using a coaxial detector having a segmented anode and a hole in the center and centered on the axis of said ion beam, and the hole allowing said beam of ions to scatter from a sample backward to said coaxial detector.
- 17. The method as defined in claim 16 wherein said coaxial detector comprises a segmented detector.
- 18. The method as defined in claim 14 wherein said ion beam focus means comprises an einzel lens capable of focusing said ion beam to a small spot, thereby providing high spatial resolution for performing high resolution surface analysis.
- 19. The method as defined in claim 11 where said step of producing a pulsed beam of ions includes executing a computer program by a computer to establish an ion beam pulse frequency based on ion beam mass and energy.
- 20. The method as defined in claim 11 wherein said step of detecting particles includes detection of more than one signal event per ion pulse by routing each said signal event to separate channels of a multi-channel input scaler.
- 21. The method as defined in claim 11 further including the step of ion beam analyzing a thin film during deposition.
- 22. The method as defined in claim 21 wherein said method is carried out at high pressure using a single differential pumping aperture plate disposed before the detector.
- 23. The method as defined in claim 11 further including the ability to perform depth profiling between performing time of flight scattering by the step of stopping pulsing of said beam of ions by removing deflection voltages applied to said deflection plates thereby applying a DC current of said beam of ions to the sample.
- 24. The method as defined in claim 11 further including the step of analyzing data produced by detecting the particles, including the steps of designating different portions of a memory for different detectors of said spectrometer and applying an offset to each detector signal and adding data characteristic of the detector signal into designated portions of said memory.
- 25. A time-of-flight direct recoil ion scattering spectrometer, comprising:
- means for producing a paraxial beam of ions;
- means for detecting particles emitted from a sample bombarded by said pulsed beam of ions;
- a plurality of deflection plates for applying deflection fields to said beam of ions, said deflection plates separated from each other by an ion drift space for removing ions with laterally directed velocities; and
- means for providing differential pumping of an incoming ion beam path and an outgoing beam path of said spectrometer.
Government Interests
This invention was made with Government support under Contract No. W-31-109-ENG-38 awarded by the Department of Energy. The Government has certain rights in this invention.
US Referenced Citations (7)