In a tandem mass spectrometer means are provided for molecular activation
of ions prior to fragmentation. An embodiment of a tandem mass
spectrometer comprises a first collision cell receiving analyte ions
having an internal energy and a second collision cell situated downstream
from the first collision cell wherein the first collision cell increases
the internal energy of the analyte ions prior to entry of the ions into
the second collision cell, the increase in internal energy imparted in
the first collision cell alone being insufficient to fragment a
substantial portion of the analyte ions. Another embodiment includes a
collision cell with a heating device situated adjacent to the collision
cell for controlling the temperature within the collision cell.