Mass spectrometer system and mass spectrometry method

A mass spectrometry method in a mass spectrometer system that comprises a chamber having an ion emitting unit to emit metal ions in said chamber with a communicating hole;

• a molecule introduction unit which introduces neutral molecules into the chamber;
• a gas introduction unit which introduces another gas into the chamber;
• and a mass analyzer which analyzes a mass of the neutral molecules having the metal ions attached and emitted from the communicating hole, the method comprising the step of controlling a temperature of a region where the metal ions attach to the neutral molecules in the chamber,
• wherein in the controlling step, plotting an attachment energy of the metal ions attached to the neutral molecules in the chamber along an abscissa and the temperature of the region where the metal ions attach to the neutral molecules along an ordinate, the temperature of the region is adjusted so as to make the temperature fall within a range obtained by excluding a range corresponding to the temperature of the region from 150° C. to 200° C. (both inclusive) from a range surrounded by the temperatures of the region [° C.]=150×attachment energy [eV], 100×attachment energy [eV]−50, and 20° C., and attachment energies [eV]=2.1 and 0.5.