Ion trap with spatially extended ion trapping region
AssigneeMicromass UK Limited
InventorsKevin Giles, Martin Raymond Green, Daniel James Kenny, David J. Langridge, Jason Lee Wildgoose
Life of this patent
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Abstract
A mass or mass to charge ratio selective ion trap is disclosed which directs ions into a small ejection region. A RF voltage acts to confine ions in a first (y) direction within the ion trap. A DC or RF voltage acts to confine ions in a second (x) direction. A quadratic DC potential well acts to confine ions in a third (z) direction within the ion trap. The profile of the quadratic DC potential well progressively varies along the second (x) direction.
Claims15
A mass or mass to charge ratio selective ion trap comprising:
- a first device arranged and adapted either to:
- (i) generate a radially asymmetric pseudo-potential barrier or well which acts to confine ions in a first (y) and a second (x) direction within said ion trap, or to;
- (ii) generate a pseudo-potential barrier or well which acts to confine ions in a first (y) direction and a DC potential barrier or well which acts to confine ions in a second (x) direction within said ion trap;
- a second device arranged and adapted to generate a substantially quadratic DC potential well which acts to confine ions in a third (z) direction within said ion trap;
- and
- a third device arranged and adapted to excite ions in said third (z) direction so as to mass or mass to charge ratio selectively eject ions in said second (x) direction or in said third (z) direction from an ion ejection region of said ion trap;
- wherein a profile of said substantially quadratic DC potential well progressively varies along two directions, said second (x) direction and said third (z) direction, so that an electric field is maintained along said second (x) direction, wherein a magnitude of the electric field in said second (x) direction varies with position in said third (z) direction so that said electric field urges, channels or directs ions towards said ion ejection region wherein said electric field causes ions to experience substantially different acceleration fields in said second (x) direction dependent upon a relative position of said ions in said third (z) direction.
A method of mass or mass to charge ratio selective ejection of ions from an ion trap comprising:
- either:
- (i) generating a radially asymmetric pseudo-potential barrier or well which acts to confine ions in a first (y) and a second (x) direction within said ion trap, or
- (ii) generating a pseudo-potential barrier or well which acts to confine ions in a first (y) direction and a DC potential barrier or well which acts to confine ions in a second (x) direction within said ion trap;
- generating a substantially quadratic DC potential well which acts to confine ions in a third (z) direction within said ion trap, wherein a profile of said substantially quadratic DC potential well progressively varies along two directions, said second (x) direction and said third (z) direction, so that an electric field is maintained along said second (x) direction, wherein a magnitude of the electric field in said second (x) direction varies with position in said third (z) direction so that said electric field urges, channels or directs ions towards an ion ejection region of said ion trap wherein said electric field causes ions to experience substantially different acceleration fields in said second (x) direction dependent upon a relative position of said ions in said third (z) direction;
- and
- exciting ions in said third (z) direction so as to mass or mass to charge ratio selectively eject ions in said second (x) direction or in said third (z) direction.
Dependencies are inferred from the claim text.