Ion scattering spectrometer with neutralization

Claim 1

An elemental analyzing apparatus adapted to fit within an evacuatable chamber, said apparatus comprising: a. an ion beam generating means for producing and focusing a monoenergetic beam of noble gas primary ions; b. an electrically conductive target holder positioned relative to said beam generating means to support a target in the path of a said beam to have the ions of said beam impinge on a surface of said target; c. energy analyzing means positioned adjacent said target to receive primary ions scattered elastically from an atomic monolayer of a said surface for selectively transmitting the received scattered primarY ions having a preselected energy value throughout an energy spectrum; d. ion detector means for converting the transmitted ions into an electrical signal; e. a filament means for emitting electrons, said filament means being disposed adjacent said target holder and in line-of-sight with a said target thereon; f. power supply means for energizing the filament to emit electrons therefrom and to bias said filament negative with respect to said target holder; and g. circuit means connected to said target holder for sensing a change in current flowing through said target holder as a result of the ion bombardment of an insulating target and the flow of electrons from said filament and for adjusting said power supply means to stabilize the current flowing through said target holder to a predetermined value whereby a said target surface is maintained at substantially the target holder potential.

Claim 6

A method for the precise elemental analysis of a target of an electrically insulating material comprising the steps of: a. generating a monoenergetic noble gas primary ion beam; b. positioning a target on an electrically conductive target holder, positioned in the path of a said beam with a surface of said target in the path of said beam to impinge said beam of ions on said surface; c. analyzing the energy of elastically scattered primary ions throughout an energy spectrum by selectively transmitting the scattered primary ions and producing an electrical signal by ion detector means detecting the transmitted ions; d. energizing a filament disposed in line-of-sight relationship to said target to produce an electron current flow to said target holder and to place the filament potential at a few volts less than the target holder potential; e. measuring said current flow through said target holder; and f. adjusting the current flow through the filament in response to changes in the current flowing through the target holder to neutralize any charges accumulated on the surface caused by ion impingement, and to maintain the target surface and the target holder at the same stable potential.

Claim 7

A method for the precise elemental analysis of a target of an electrically insulating material comprising the steps of: a. generating a monoenergetic noble gas primary ion beam; b. positioning a target on an electrically conductive target holder, positioned in the path of a said beam with a surface of said target in the path of said beam to impinge said beam of ions on said surface; c. analyzing the energy of elastically scattered primary ions throughout an energy spectrum by selectively transmitting the scattered primary ions and producing an electrical signal by ion detector means detecting the transmitted ions; d. energizing a filament disposed in line-of-sight relationship to said target to produce an electron current flow to said target holder and to place the filament potential at a few volts less than the target holder potential; e. measuring said current flow through said target holder; and f. adjusting the current flow through the filament in response to changes in the current flowing through the target holder to neutralize any charges accumulated on the surface caused by ion impingement, and to maintain the target surface and the target holder at the same stable potential.