Charged particle extraction arrangement
AssigneeKratos Analytical Limited
InventorsStephen P. Thompson, Mark G. Dowsett
Life of this patent
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Abstract
An arrangement is described for extracting charged particles which have been emitted from a sample due to the impact of a primary ion beam. The arrangement comprises an electrode arrangement effective to produce an electric potential which is non-linear along a chosen direction of travel of the particles. A system of einzel lenses is effective to match the trajectories of the particles passing from the electrode means to the analyser of a mass spectrometer.
Claims18
An apparatus for extracting charged particles which have been emitted from a solid or liquid sample comprising electrode means for producing an electric potential which is non-linear along a chosen direction of travel of the particles, the resultant electric field being substantially confined to the region of the electrode means, the field being such that the initial potential gradient experienced by the emitted particles is small compared to the final potential gradient due to the non-linearity of the electric field, and a focusing means effective to match the trajectories of the particles passing from the electrode means to the input of a charged particle analyser means.
An apparatus according to claim including means for performing post ionisation, for example electron impact or laser, in a volume close to the sample containing a substantially small electric field so that the post ionised ions enter the mass spectrometer with a small energy spread.
A method for extracting charged particles which have been emitted from a sample comprising producing an electric potential which is non-linear along a chosen direction of travel of the particles, the resultant electric field being substantially confined to the region of the electrode means which produces the electric potential, the field being such that the initial potential gradient experienced by the emitted particles is small compared to the final potential gradient due to the non-linearity of the electric field, and focusing the particles so as to match the trajectories of the particles passing from the electrode means to the input of charged particle analyser means.
Dependencies are inferred from the claim text.