with atmospheric pressure ionization mass spectrometer.

摘要

PURPOSE:To dissociate and remove cluster ions easily and efficiently by setting an electrical drift field at the intermediate pressure section while simultaneously arranging an electrode for setting the pressure gradient at the intermediate pressure section while touching it tightly with an electrode for partitioning an atmospheric pressure ion source from the intermediate pressure section. CONSTITUTION:Sample gas 15 containing trace constituent is led through a sample lead-in tube 1 to an ion source 3 and is subject to primary ionization through corona discharge at the tip of a needle electrode 2. As secondary ionization is performed, charge transfer reaction from main component ions having high ionization potential to the target trace constitution molecules having low ionization potential is performed to ionize the trace constitution molecules. Cluster ions in the ions led into the intermediate pressure section 6 are excited by the collision with neutral molecules at the intermediate pressure section 6 and transformed to be dissociated molecular ions or quasi-molecular ions. The ions will move in the electrical drift field and impinge against the neutral molecules so that the kinetic energy is converted into the inner energy, and many times of impingement will cause sufficient excitation of the inner energy resulting in dissociation of cluster coupling.