Claims
- 1. A method of measuring a mass spectrum of sample material which comprises the steps of
- defining a three-dimensional electrical inharmonic quadrupole ion storage field in which ions with mass-to-charge ratios in a range of interest can be simultaneously trapped;
- introducing or creating sample ions into the quadrupole field whereby ions of interest are simultaneously trapped and perform mass-to-charge specific secular movements;
- changing this quadrupole field so that simultaneously and stably trapped ions of consecutive mass-to-charge ratios encounter a nonlinear resonance of their secular movements, will increase thereby their secular movement amplitudes, and then leave the trapping field; and detecting the ions of sequential mass-to-charge ratios as they leave the trapping field.
- 2. A method of claim 1 in which the inharmonic quadrupole ion storage field is generated by the superposition of an exact quadrupole field with a finite or infinite sum of co-axial multipole fields.
- 3. Apparatus for measuring a mass spectrum of a sample material in which a storage field is generated by a QUISTOR of the type having a ring electrode and spaced end electrodes whereby the inharmonic quadrupole field is generated by the shape of the electrode surfaces being in the shape of two rotation-symmetric hyperbolic end caps and a rotation-symmetric hyperbolic torrid with an angle of the inscribed asymptotic double-cone deviating from 1:1.414.
- 4. Apparatus as in claim 3 with a cone angle between 1:1.34 and 1:1.410.
- 5. Apparatus as in claim 4 characterized in that the ions stored in the field are generated outside the exact center of the field.
- 6. Apparatus as in claim 5 in which the ions are generated in a distinct location outside the center of the field.
- 7. Apparatus as in claim 6 in which the ion generation is located in the r-plane in a distance from the field center of about 1/8 to 1/6 of the inner diameter of the ring electrode.
- 8. Apparatus as in claim 6 in which the ion generation is located in the field axis in a distance of about 1/8 to 1/4 of the distance between the end electrodes.
Priority Claims (1)
Number |
Date |
Country |
Kind |
8910285 |
Feb 1989 |
DEX |
|
GOVERNMENTAL INTEREST
The Government has rights in this invention pursuant to Contract No. DAAA-15-87-C-0008 awarded by the U.S. Army.
US Referenced Citations (5)