Patent ID: 7893401

Claim:
A mass spectrometer including: a pulsed ion source, a first ion trap for trapping ions generated by the pulsed ion source and for locating trapped ions for subsequent ejection from the first ion trap, a gas inlet means for introducing a pulse of cooling gas into said first ion trap at a peak pressure suitable for enabling the first ion trap to trap said ions, a pump means for reducing a pressure of said cooling gas before the trapped ions are ejected from the first ion trap, and a second ion trap for receiving and analyzing ions ejected from the first ion trap, said pulsed ion source including a flat sample plate on which a sample is deposited and which forms an end wall of the first ion trap, whereby said pulsed ions are generated inside the first ion trap, and said gas inlet means including a valve having an opening time less than the pump down time constant achieved by said pump means.