Patent ID: 8237109
Filing Date: 2012-08-07
Classification: H01J

Abstract:
1. A method for fragmenting ions comprising: (a) retaining the ions in an ion-confinement region of an ion trap for a retention time; (b) creating a non-steady-state pressure increase within the ion-confinement region by delivering a neutral gas into the ion trap for at least a portion of the retention time to raise the pressure in the ion-confinement region to a varying first elevated-pressure in the range between about 5.5×10 (c) exciting at least a portion of the ions within the ion-confinement region by subjecting them to an auxiliary alternating electrical field having an amplitude of less than about 500 mV (d) reducing the pressure within the ion trap to a first restored-pressure value prior to the end of the retention time; and (e) ejecting the ions from the ion trap at the end of the retention time.