THE INFINITY CELL - A NEW TRAPPED-ION CELL WITH RADIOFREQUENCY COVERED TRAPPING ELECTRODES FOR FOURIER-TRANSFORM ION-CYCLOTRON RESONANCE MASS-SPECTROMETRY

The excitation event in Fourier transform ion cyclotron resonance mass spectrometry is optimized in order to obtain more reliable relative signal intensities and enhance the ion-selection performance in multi-tandem mass spectrometric experiments. Standard trapped-ion cells suffer from the undesirable ejection of ions along the symmetry axis (z-axis) of the cell, which is oriented parallel to the magnetic field lines. This z-ejection effect is difficult to predict, and thus difficult to avoid, especially when complicated broad-band excitation schemes are applied to the ions. An improved trapped-ion cell design, referred to as the 'Infinity Cell', is discussed which eliminates z-ejection. The Infinity Cell concept is based on the finding that it is possible to model the electric excitation field of an infinitely long cell with a cell of finite dimensions. The virtual elimination of z-ejection effects is demonstrated in several suitable experiments by comparing the operation of the standard cell and the Infinity Cell.