A new technique for time-resolved daughter ion mass spectrometry on the microsecond to millisecond time scale using an electrostatic ion storage ring.

A new method for time-resolved daughter ion mass spectrometry is presented, based on the electrostatic ion storage ring in Aarhus, ELISA. Ions with high internal energy, e.g., as a result of photoexcitation, dissociate and the yield of neutrals is monitored as a function of time. This gives information on lifetimes in the microsecond to millisecond time range but no information on the fragment masses. To determine the dissociation channels, we have introduced pulsed supplies with switching times of a few microseconds. This allows rapid switching from storage of parent ions to storage of daughter ions, which are dumped into a detector after a number of revolutions in the ring. A fragment mass spectrum is obtained by monitoring the daughter ion signal as a function of the ring voltages. This technique allows identification of the dissociation channels and determination of the time dependent competition between these channels.