| 摘要 |
An unbalanced radio frequency voltage is supplied between two pairs of conductive rods (10a, 10c; 10b, 10d) of a quadrupole mass filter of a mass spectrometer system. Means (S2) are provided for d.c. voltage polarity reversal for monitoring positive and negative ions. The d.c. voltage is derived by rectification of the radio frequency voltage. |
