Axial ejection in a multipole mass spectrometer
US6177668A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jun 1, 1998 |
| Grant date | Jan 23, 2001 |
| Priority date | — |
| Expiry date | Jun 1, 2018 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01J49/427
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A method of operating a mass spectrometer having an elongated multipole rod set, in which a two dimensional RF field radially contains trapped ions in a mass to charge range of interest, and in which the ions are contained axially by a barrier field on an end lens and to which a low voltage DC is applied. Trapped ions are axially mass selectively ejected by taking advantage of the mixing of the degrees of freedom induced by the fringing fields and other anti-harmonicities in the vicinity of the end lens. Thus, ions can be mass selectively ejected at the exit end at the same time as ions are being admitted into the entrance end of the rod set, thereby taking better advantage of the ion flux from a continuous ion source. The axial mass selective ejection is performed by applying an auxiliary AC voltage to the end lens, or to the rods themselves, or both, and by scanning either the auxiliary AC voltage or the RF voltage on the rod set. Trapped ions can be concentrated near the exit lens by applying an axial field in the direction of the lens, or can be depleted by applying the axial field in the opposite direction. The axial field can be oscillated to dissociate trapped ions.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.