Linear ion trap with an imbalanced radio frequency field
AssigneeLeco Corporation
InventorAnatoli N. Verentchikov
Life of this patent
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Abstract
An imbalanced radio frequency (RF) field creates a retarding barrier near the exit aperture of a multipole ion guide, in combination with the extracting DC field such that the barrier provides an m/z dependent cut of ion sampling. Contrary to the prior art, the mass dependent sampling provides a well-conditioned ion beam suitable for other mass spectrometric devices. The mass selective sampling is suggested for improving duty cycle of o-TOF MS, for injecting ions into a multi-reflecting TOF MS in a zoom mode, for parallel MS-MS analysis in a trap-TOF MS, as well as for moderate mass filtering in fragmentation cells and ion reactors. With the aid of resonant excitation, the mass selective ion sampling is suggested for mass analysis.
Claims29
A method of mass dependent ion sampling, comprising steps of:
- introducing ions into a substantially two-dimensional multipole radio frequency (RF) field;
- providing an extracting DC field at an exit of the multipole RF field;
- and
- creating a non-zero axial RF field at the exit of the multipole RF field.
An ion trap comprising:
- an RF multipole ion guide supplied with two radio frequency (RF) phases of an RF signal;
- and
- an exit electrode,
- wherein the two RF phases are brought out of balance.
Dependencies are inferred from the claim text.