Abstract: An ICR ion trap comprises electrically conductive side plates (1) extending in parallel to one axis (Z), and electrically conductive end plates (5,6) extending perpendicularly to the said axis (Z). Additional electrode plates (8,9) are arranged at a certain spacing from the said end plates (5,6) and can be supplied with trapping potentials of a polarity opposite to the polarity of the potentials applied to the said end plates so that an outer space is defined in which electrodes of opposite sign are trapped. Following analysis and elimination of the ions contained in the inner space, the ions of opposite sign can be trapped in the inner space for subsequent analysis. The arrangement provides also the possibility to observe recombination reactions between ions of different signs.

Abstract: A method of operating an ICR spectrometer comprising a measuring cell (1) having a plurality of side walls (3, 4) designed as rf electrodes and arranged symmetrically to an axis (2) extending in parallel to the field direction of a magnetic field, and further electrically insulated trapping electrodes (5, 6) arranged on both sides of the cell, viewed in the direction of the axis, which trapping electrodes can be supplied with trapping potentials of the polarity of the ions under examination in order to prevent, to a large extent, the ions from leaving the measuring cell (1) in the direction of the axis, provides that, in order to minimize the components of the electric rf field directed in parallel to the axis, which act upon the ions in the measuring cell (1), additional electric rf signals are applied to at least one said trapping electrode (5) on both sides of the said measuring cell (1).

Abstract: An ICR ion trap comprises electrically conductive side plates (1) extending in parallel to one axis (Z), and electrically conductive end plates (5,6) extending perpendicularly to the said axis (Z). Additional electrode plates (8,9) are arranged at a certain spacing from the said end plates (5,6) and can be supplied with trapping potentials of a polarity opposite to the polarity of the potentials applied to the said end plates so that an outer space is defined in which electrodes of opposite sign are trapped. Following analysis and elimination of the ions contained in the inner space, the ions of opposite sign can be trapped in the inner space for subsequent analysis. The arrangement provides also the possibility to observe recombination reactions between ions of different signs.

Abstract: Method and apparatus for introducing ions into an ion trap of an ion cyclotron resonance spectrometer, the ion trap being arranged in a constant homogeneous magnetic field and comprising walls which are designed as electrodes and extend in parallel and/or perpendicularly to a symmetry axis having the direction of the magnetic field and which are supplied with electric trapping potentials retaining the ions in the ion trap, one of the walls which extend perpendicularly to the magnetic field being provided with a hole, the method including the steps of generating the ions outside the ion trap, forming the ions into an ion beam, directing the ion beam upon the hole in the one wall of the ion trap, in the direction of the magnetic field, and reducing thereafter the velocity component, in the direction of the magnetic field, of the ions which have passed the hole and entered the ion trap, below the value determined by the trapping potentials which is needed by the ions for leaving the ion trap, characterized in th