Electrostatic ion mirrors
AssigneeLeco Corporation
InventorsAnatoly N. Verenchikov, Mikhail I. Yavor, Timofey V. Pomozov
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Abstract
An electrostatic ion mirror is disclosed providing fifth order time-per-energy focusing. The improved ion mirror has up to 18% energy acceptance at resolving power above 100,000. Multiple sets of ion mirror parameters (shape, length, and voltage of electrodes) are disclosed. Highly isochronous fields are formed with improved (above 10%) potential penetration from at least three electrodes into a region of ion turning. Cross-term spatial-energy time-of-flight aberrations of such mirrors are further improved by elongation of electrode with attracting potential or by adding a second electrode with an attracting potential.
Claims40
An electrostatic isochronous time-of-flight or ion trap analyzer comprising:
- two parallel and generally aligned grid-free ion mirrors separated by a drift space, wherein the ion mirrors are substantially elongated in one transverse direction to form a two-dimensional electrostatic field either of a planar symmetry or a hollow cylindrical symmetry, and wherein the ion mirrors includes one or more mirror electrodes having parameters that are selectively adjustable and adjusted to provide less than 0.001% variations of flight time within at least a 10% energy spread for a pair of ion reflections by said ion mirrors.
An electrostatic isochronous time-of-flight or ion trap analyzer comprising:
- two parallel and aligned grid-free ion mirrors separated by a drift space, wherein at least one of the ion mirrors includes at least three electrodes with retarding potential, and wherein the ion mirrors are substantially elongated in one transverse direction to form a two-dimensional electrostatic field, and further wherein the electrostatic field has a symmetry that is either planar or hollow cylindrical;
- and
- at least one electrode with an accelerating potential compared to the drift space, wherein sizes of the at least three electrodes with retarding potential are selectively adjustable and adjusted to provide potential penetration within a middle electrode window, on optical axis and in a middle region between adjacent electrodes above one tenth of their potential, and wherein, for the purpose of improving resolving power of said electrostatic analyzer, wherein the electrodes of the ion mirrors have parameters that are selectively adjustable and adjusted to provide less than 0.001% variations of flight time within at least a 10% energy spread for a pair of ion reflections by said ion mirrors.
A method of mass spectrometric analysis in isochronous multi-reflecting electrostatic fields comprising the following steps:
- forming two regions of electrostatic fields between ion mirrors that are separated by field-free space, wherein the ion mirror field is substantially two-dimensional and extended in one direction to have either planar symmetry or a hollow cylindrical symmetry;
- forming at least one region with an accelerating field;
- within at least one ion mirror field, forming a retarding field region with at least three electrodes at a reflecting end, wherein the three electrodes include retarding potentials such that at the turning point of ions, the mean kinetic energy provides potential penetration above 10%;
- and
- adjusting an axial distribution of said ion mirror field to provide less than 0.001% variations of flight time within at least 10% energy spread for a pair of ion reflections by said mirror fields.
A planar ion mirror of an electrostatic isochronous analyzer, comprising:
- a first mirror electrode forming a first end of the ion mirror, said first mirror electrode being set with a retarding potential;
- a second mirror electrode residing adjacent to said first mirror electrode, said second mirror electrode being set with a retarding potential and said second mirror having a length (L) to window height (H) ratio between 0.2 and 0.5;
- a third mirror electrode residing adjacent to said second mirror electrode, said third mirror electrode being set with a retarding potential and said third mirror having a length (L) to window height (H) ratio between 0.6 and 1.0;
- and
- a fourth mirror electrode being set with an accelerating potential,
- wherein each of said mirror electrodes have the same window height (H).
A planar ion mirror of an electrostatic isochronous analyzer, comprising:
- a first mirror electrode forming a first end of the ion mirror, said first mirror electrode being set with a retarding potential;
- a second mirror electrode residing adjacent to said first mirror electrode, said second mirror electrode being set with a retarding potential and said second mirror having a length (L) to window height (H) ratio between 0.01 and 0.1;
- a third mirror electrode residing adjacent to said second mirror electrode, said third mirror electrode being set with a retarding potential and said third mirror having a length (L) to window height (H) ratio between 0.5 and 0.7;
- a fourth mirror electrode residing adjacent to said third mirror electrode, said fourth mirror electrode being set with a potential equal to that of a field-free region of the electrostatic isochronous analyzer to decouple a retarding electrostatic field formed by the first, second, and third ion mirrors of the mirror from the accelerating electrostatic field formed by the fifth ion mirror of the mirror;
- and
- a fifth mirror electrode being set with an accelerating potential,
- wherein each of said mirror electrodes have the same window height (H), wherein a first gap is formed between said first mirror electrode and said second mirror electrode, wherein a second gap is formed between said second mirror electrode and said third mirror electrode, and wherein the length (L) of the second mirror electrode is smaller than lengths of both said first gap and said second gap.
Dependencies are inferred from the claim text.