Patent ID: 8618475

Claim:
An ion mobility spectrometer comprising: a source of purely buffer gas, a drift tube defining a drift tube inlet configured to receive ions and a drift tube outlet, the drift tube receiving the buffer gas therein from the source of buffer gas, a first ion gate separate from and positioned between the drift tube inlet and the drift tube outlet, the drift tube defining a first drift tube region between the drift tube inlet and the first ion gate, the first drift tube region responsive to a first set of voltage signals to separate ions in time as a function of ion mobility, the first ion gate responsive to a first ion gate control signal to impede passage of ions from the first drift tube region through the first ion gate and to a second ion gate control signal to allow passage of ions from the first drift tube region through the first ion gate, a first set of voltage sources to produce the first set of voltage signals, a first ion activation region positioned between the first ion gate and the drift tube outlet, the drift tube defining a second drift tube region between the first ion activation region and the drift tube outlet, the second drift tube region responsive to a second set of voltage signals to separate ions as a function of ion mobility, the first ion activation region responsive to a third set of voltage signals to selectively establish an electric field in the first ion activation region that induces structural changes in at least some of the ions that pass through the first ion gate by inducing changes in the shapes of at least some of the ions via collisions with the buffer gas without fragmenting the at least some of the ions, a second set of voltage sources to produce the second set of voltage signals, a third set of voltage sources to produce the third set of voltage signals, and a processor electrically coupled to the first ion gate and producing the first and second ion gate control signals.