Mass spectrometer and mass spectrometry

A spectrometry method, comprising:

• a sample introducing step, of introducing a sample to a dielectric unit, the dielectric unit having a sample introducing unit and a sample discharging unit, and the dielectric unit being provided between a first electrode and a second electrode;
• a voltage applying step, of applying an alternating current voltage to either one of the first electrode and the second electrode, by using a power source;
• an ionizing step, of ionizing the sample in the dielectric unit, while using an irradiation controlling unit to irradiate light to an area between the first electrode and the second electrode;
• and
• an analyzing step, of analyzing the ionized sample after a dielectric barrier discharge in the sample discharging unit of the dielectric unit.