Time-of-flight mass spectrometer with an aperture enabling tradeoff of transmission efficiency and resolution
First Claim
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1. A time-of-flight mass spectrometer having a controllable resolution, said spectrometer comprising:
- a barrier having an aperture;
a detector;
means for producing, from a sample substance, a beam of sample ions, at least part of which passes through said aperture to said detector;
each ion being characterized by a time-of-flight extending from a time of generation of that ion until said ion is detected by said detector; and
said ions exhibiting at said aperture a time-of-flight distribution that is a function of a lateral distance from an axis parallel to said beam and located within said beam; and
means for varying the resolution by varying how much of this beam passes through said aperture.
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Abstract
A time-of-flight mass spectrometer in which sample ions are generated from a target and are focussed into an ion beam that is incident onto a detector. A barrier that defines an aperture in the path of the ion beam is positioned to block ions having an extra large deviation from an average time-of-flight of the ions, thereby improving resolution. The aperture can be adjusted to adjust a tradeoff between sensitivity and resolution. Alternatively, the position of the aperture or the bias on an einzel lens can be adjusted to control this resolution.
53 Citations
12 Claims
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1. A time-of-flight mass spectrometer having a controllable resolution, said spectrometer comprising:
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a barrier having an aperture; a detector; means for producing, from a sample substance, a beam of sample ions, at least part of which passes through said aperture to said detector; each ion being characterized by a time-of-flight extending from a time of generation of that ion until said ion is detected by said detector; and said ions exhibiting at said aperture a time-of-flight distribution that is a function of a lateral distance from an axis parallel to said beam and located within said beam; and means for varying the resolution by varying how much of this beam passes through said aperture. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A time-of-flight mass spectrometer having a controllable resolution, said spectrometer comprising:
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a barrier having an aperture; a detector; means for producing, from a sample substance, a beam of sample ions, at least part of which passes through said aperture to said detector; each ion being characterized by a time-of-flight extending from a time of generation of that ion until said ion is detected by said detector; and said ions exhibiting at said aperture a time-of-flight distribution that is a function of a lateral distance from an axis parallel to said beam and located within said beam; and means for varying the resolution by varying how much of this beam passes through said aperture; wherein said aperture has an adjustable dimension that can be changed to adjust the resolution of this spectrometer.
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12. A time-of-flight mass spectrometer having a controllable resolution, said spectrometer comprising:
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a barrier having an aperture; a detector; means for producing, from a sample substance, a beam of sample ions, at least part of which passes through said aperture to said detector; each ion being characterized by a time-of-flight extending from a time of generation of that ion until said ion is detected by said detector; and said ions exhibiting at said aperture a time-of-flight distribution that is a function of a lateral distance from an axis parallel to said beam and located within said beam; and means for varying the resolution by varying how much of this beam passes through said aperture; wherein said barrier contains a plurality of apertures of different sizes and said barrier can be translated in a direction lateral to said ion beam to selectively align any selected one of these apertures in the path of the ion beam to adjust a resolution of this spectrometer.
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Specification