Black canyons for ions stored in an ion‐trap mass spectrometer

Effects from higher order non‐linear resonances, ‘black canyons’, have been observed for ions stored within the quadrupole ion‐trap mass spectrometer. At specific q z values, higher‐order field effects were observed to cause decreased intensity of chemical ionization (CI) reagent ions, due to ineffcient storage, as well as collision‐induced dissociation. Efects have been observed, whether or not the CI reagent ions are mass‐selected, and exibit increased severity with longer storage times. Previous reports have shown ‘black holes’ due to inefficient storage of product ions in tandem (MS/MS) spectra, but have reported no such effects in normal mass spectra. Without employing resonant excitation, higher‐order field effects were investigated and found to occur continuously along iso‐β z lines for β z = 1/3, 1/2, and 2/3. Described in this paper are the directs from higher‐order fields on ions stored at specific a z values, and indirec effects by those ions. Also described in this paper is new evidence for ‘black canyons’ occurring at β z = 1/3 at negative a z values.