QUADRUPOLE MASS SPECTROMETER

摘要

PURPOSE:To obtain a device which has high sensitivity and less noise by providing a modulating electrode to the detecting part of a quadrupole mass spectrometer, modulating ion current by said electrode and detecting signal by a phase system. CONSTITUTION:A quadrupole mass spectrometer is constituted of an ion source part 1, a quadrupole filter part 2 and a detecting part 3. The modulating potential waveform 16 made by an oscillating circuit 13 is impressed to the modulating electrode 10 of the part 3 and the ion past the part 2 is modulated by said electrode. The modulated ion enters a collector electrode 12 and is amplified by an amplifier 14 and thereafter the amplified ion current is subjected to phase detection by a phase detector 15, by which the signal is detected. The peak value VP of the waveform 16 to be impressed to the modulating electrode is made approximately equal to the anode potential of the ion source.