Abstract: The invention relates to ion-optical RF-operated electrode systems such as ion guide systems, ion fragmentation systems, ion filtering systems or ion storage systems which require additional DC potential gradients by means of DC voltages on resistance systems. The invention consists in supplying the DC voltages via center taps between several separate secondary windings of an RF transformer generating the RF voltage.

Abstract: A method and a device for the mass selective excitation of the secular oscillations of selected ion types in an RF quadrupole ion trap, including the simultaneous excitation of more than one ion type, is disclosed. The secular oscillation frequency is excited by resonances with specific frequencies of the frequency bands of the additional alternating fields, the frequency bands being generated digitally at a basic pulse rate .OMEGA.. Interfering frequency side bands .OMEGA.-.omega., .OMEGA.+.omega., 2.OMEGA.-.omega., 2.OMEGA.+.omega., etc. arise, however, for each frequency .omega. within the frequency bands. These side bands can excite and eliminate other ions, which are not to be eliminated, in an undesired manner. The invention comprises forming the side bands in such a way that they only excite the selected ions.

Abstract: The measuring process for generating mass spectra using a sequentially-scanned quadrupole ion trap mass spectrometer, is improved by controlling the measurement of the ion packages ejected from the ion trap so that measurement takes place starting at the anticipated exit times of the ion packages and measurement continues only as far as possible for a time duration corresponding to the length of the ion packages. Measuring only during ion package ejection enables a measurement for the total number of ejected ions having a selected mass to be obtained by means of digital addition of the individual package measurements. Subsequent processing of the data can be carried out with practically only the fluctuations of normal ion counting statistics.

Abstract: For mass-spectroscopic examinations of gas mixtures a mass spectrometer is used which comprises a quistor in which ions of the gas mixture whose charge-to-mass ratio is located in a predetermined range are stored by generating an electromagnetic field. By varying the field parameters, the ions are forced successively to leave the ion trap. The intensity of the ion flow leaving the ion trap is measured as a function of the variation of the field parameters. For improving the resolution, one uses a quistor of the type where the distance-related ratio Q of the radii of the inscribed vertex circles of the electrodes comply with the condition Q.ltoreq.3.990, wherein ##EQU1## R.sub.e being the radius of the cross-section of the vertex of the end electrodes (3,5);R.sub.r being the radius of the cross-section of the vertex of the annular electrode (4);z.sub.o being the distance between the vertex of each end electrode (3,5) and the center of the quistor; andr.sub.

Abstract: A method for the measurement of mass spectra by three dimensional quadrup fields (QUISTORs) is presented, in which the ions are mass-to-charge selectively ejected by a selected nonlinear resonance effect in an inharmonic QUISTOR. In order to enhance scan speed and mass resolution, the ejection of a single kind of ions can be confined to a very small time interval, either by the generation of ions within a small volume outside the field center, or by an excitation of the secular amplitudes by an additional RF voltage across the end electrodes, shortly before the ions encounter the sum resonance condition. An instrument for this method is described.

Abstract: In a quadrupole ion store (QUISTOR), a sample is analyzed by increasing the mplitude of the harmonic, or "secular", oscillations of selected stably trapped ions so that they leave the trapping field. In a preferred embodiment, deviations from the ideal electrode geometry are incorporated into the QUISTOR to produce resonance phenomena between the r and z secular oscillations, thereby increasing the amplitude of oscillations in the z direction.