AN ION TRAP STORAGE TIME-OF-FLIGHT MASS-SPECTROMETER

An ion tmp/time-of-flight (TOF) mass spectrometer combination has been developed in order to combine the storage capabilities of an ion trap with the speed and resolution of a time-of-flight device. The ion tmp is an rf quadrupole tmp which operates in the total storage mode, i.e., with the dc voltage=0 on the end caps and rf voltage on the ring electrode. The trap has an ion storage time of > 2 s at an rf potential of 310 V(pp). The stored ions are ejected into the time-of-flight device using a -150 V dc pulse on the exit end cap which causes the ion trajectories in the trap to become unstable. The ions are mass analyzed using either a linear or reflectron TOF. In the linear mode the resolution is 240 while in the reflectron mode a resolution of 1300 at m/z 93 is achieved. The storage capabilities of this device may have important applications towards enhancing sensitivity, the study of very slow metastable decay, and photodissociation mass spectrometry and spectroscopy.