Apparatus and methods for spatially and temporarily sorting ions using rf travelling waves

A mass spectrometer system comprising:

• an ion source configured to generate a plurality of ions by ionization of a sample, the ions comprising a plurality of mass-to-charge ratio (m/z) values;
• an ion guide having, therein, a gas at a pressure that is greater than or equal to 0.01 Torr and comprising:
• an ion inlet configured to receive a stream of the ions from the ion source;
• an ion outlet;
• and
• a series of electrodes disposed between the ion inlet and the ion outlet, the series of electrodes defining an ion occupation volume and an axis of the ion guide between the ion inlet and the ion outlet;
• and
• one or more power supplies electrically coupled to the series of electrodes, the one or more power supplies configured to:
• apply a set of radio-frequency (RF) voltage waveforms to the series of electrodes that confine the ions within the ion occupation volume and that generate a plurality of moving pseudopotential wells that exert forces on the ions that urge the ions to migrate either from the inlet end to the outlet end or from the outlet end to the inlet end;
• and
• apply, simultaneously with the application of the set of RF voltage waveforms, a set of direct-current (DC) electrical potentials to the series of electrodes or to two or more auxiliary electrodes that generate forces on the ions within the ion guide that are independent of mass-to-charge ratio (m/z) and that oppose the forces exerted by the moving pseudopotential wells.