Creating an evanescent ion/ion reaction region within a low-pressure linear ion trap

► A new environment for conducting ion/ion reactions within a linear ion trap (LIT) mass spectrometer is proposed. ► The method uses transitory application of RF and DC voltages, as well as pulsed cooling gas, to create the ion/ion reaction region. ► This “evanescent” ion/ion reaction region can be used to perform electron-transfer dissociation (ETD) with equivalent efficiency to “static” high-pressure ion/ion reaction regions.