Abstract: There is provided a quadrupole ion trap mass spectrometer of the type having a plurality of ring electrodes and defining a trapping volume. The quadrupole potential faults arising from apertures in the electrodes are corrected by an apertured shim electrode placed within and spaced from the walls of the electrode apertures.

Abstract: There is provided a quadrupole ion trap mass spectrometer of the type having a plurality of ring electrodes and defining a trapping volume. The quadrupole potential faults arising from apertures in the electrodes are corrected by an apertured shim electrode placed within and spaced from the walls of the electrode apertures.

Abstract: There is described a method of generating product ions in a quadrupole ion trap in which the amplitude of the applied excitation voltage for an ion of a given mass-to-charge ratio (m/z) is linearly related to its mass-to-charge ratio (m/z).

Abstract: An external ion source assembly in which ion are formed in an ion volume by the interaction of energetic electrons and gas molecules. The effective energy of the electrons entering the ion volume is controlled by changing the voltage between the electron source (filament) and the ionization volume whereby ions having sufficient energy for ionizing atoms and molecules leave the electron source and enter the ionization volume only during an ionization period. The ion source assembly can be used both for electron impact ionization (EI) and for chemical ionization (CI).

Abstract: A method and apparatus is described which determines a plurality of spaced discrete frequencies covering the range of frequencies of the characteristic motion of unwanted ions and processes said discrete frequencies to generate a plurality of time dependent voltage amplitude values which vary throughout the time domain such that the frequency content of said plurality of time dependent voltage amplitude values is relatively uniform over the entire time domain, and such that the magnitude associated with the discrete frequencies is relatively uniform over the frequency domain.

Abstract: An apparatus having a signal conducting line with first and second ends is provided. The signal conducting line is configured to allow changes of impedance at space locations therealong. The signal conducting line is supported by a substrate. A signal generator is operably connected to the first end of the signal conducting line, the signal generator generating a measuring signal along the signal conducting line. The measuring signal has a predetermined characteristic, over a plurality of time intervals, when the measuring signal is undisturbed. When a disturbance is created in the measuring signal by, for example, the touching of the signal conducting line by a fingertip, the characteristic of the measuring signal varies from a predetermined deviation. Processing circuitry is operably connected to the first end of the signal conducting line so that the time interval at which the measuring signal is disturbed can be determined.

Abstract: An improved method of mass analyzing a sample in a three-dimensional quadruple ion trap with varying fields is disclosed. The dynamic range and sensitivity of previous methods is increased by controlling the number of sample ions formed in the ion trap to avoid saturation and space charge.

Abstract: A chromium or oxidized chromium surface for use in sample analyzing and ionizing apparatus, such as an ion trap or ionization chamber, which does not degrade or decompose a sample in contact with the surface.

Abstract: A filament assembly which includes spaced posts with slotted ends for positioning a filament. The ends of the filament are secured to the posts in tapered holes which receive a pin or screw to provide electrical contact and tension the filament.