Generation of multiple charged ions: Photoemission electron impact ionization

Delayed pulsed electric field was used to investigate the generation mechanism of multiple charged ions produced in the interaction of laser, metal surface and electric field on time-of-flight mass spectrometer (TOF MS). A special photoelectron generator was designed to control the energy and timing of the photoelectron beam. This modification made it possible to separate the photoionization process from photoelectron impact ionization. The experiment showed that the multiple charged ions could be produced only by the photoelectron impact, ionized step by step. A design of dual ionization configuration was presented, which could be used to study either multiphoton ionization or photoemission electron impact ionization.