Design and set-up of an external ion source coupled to a quadrupole-ion-trap reflectron-time-of-flight hybrid instrument

Further results of a new set-up for storing ions generated in an external i on source and trapped in a quadrupole ion trap in combination with a reflec tron time-of-flight mass spectrometer (ReTOF) are presented. As a result of this set-up, jet-cooled molecules are introduced as neutrals into the exte rnal ion source and ionized by multiphoton absorption processes. A selected mass range of the generated ions can be accelerated into the ion trap to b e stored without any buffer gas, The ions are not dispersed for a time dura tion of several milliseconds in the ion trap, but remain coherent in space and kinetic energy and move in narrow ion clouds describing Lissajous traje ctories. The advantage of the external ion source and its influences on the parameters of both the external ion source and the ion trap will be discus sed with respect to the signals obtained and compared with SIMION calculati ons.