| 摘要 |
A method of pulsing gas in a quadrupole ion trap to reduce excess internal energy of ions formed externally to the trap at high-vacuum conditions is disclosed. With pulsed gas introduction, pressures greater than those with which traps are normally operated can be achieved over a few milliseconds. Kinetic energy damping via collisional cooling at these higher pressures is also more efficient. Minimization of uncontrolled fragmentation (thermalization) and enhanced sensitivity are observed. After the gas is pumped out of the system, ions can be selectively isolated, dissociated and finally mass analyzed at the lower pressures either by using the quadrupole ion trap as a mass spectrometer or by ejecting ions into a time-of-flight analyzer. |
