Patent ID: 8742333

Claim:
A method for generating product ions, the method comprising: providing ions from an ion source through an inlet into an ion injection pathway having ion injection pathway ion optics; transmitting the ions along a first direction away from the inlet through the ion injection pathway into an ion selection device having ion selection device ion optics; selecting a subset of the ions in the ion selection device; wherein the subset of the ions have a preselected range of mass-to-charge ratios; and transmitting the subset of the ions having the preselected range of mass-to-charge ratios along a second direction toward the inlet through the ion injection pathway; wherein the ion injection pathway ion optics have an RF voltage component and a DC voltage component which are under independent control with respect to the ion selection device ion optics; wherein the ion injection pathway ion optics comprise two or more multipole RF devices and one or more ion lens devices, wherein the multipole RF devices and the ion lens devices are provided between the inlet and the ion selection device and wherein at least one ion lens device is provided between adjacent multipole RF devices; and wherein the subset of the ions transmitted along the second direction interact with one or more gases at a pressure greater than 0.01 Torr in the inlet or ion injection pathway and undergo dissociation, thereby fragmenting at least a portion of the subset of the ions having the preselected range of mass-to-charge ratios to generate the product ions.