MASS SPECTROMETER WITH SECONDARY ION

摘要

PURPOSE:To suppress electrification on sample surface and to improve accuracy of mass spectrometry by pulsing primary ion and irradiating a sample with the pulse ions. CONSTITUTION:When primary ion 2 collides against a sample 1, secondary ion 3 and secondary electron 6 are released. A shutter 13 may be an electrical shutter or mechanical shutter. In other words, any shutter is usable as far as the shutter can convert the continuous primary ion 2 to impulsive primary ion 2a. The pulse width of the primary ion 2a is equal to the open time (t) of the shutter 13 and the open time (t) is so determined that the product it of the current (i) flowing in the sample 1 and the time (t) attains a constant or below. If the pulse interval of the primary ion 2a is taken substantially long, the charge accumulated in the sample 1 is discharged and the surface potential V of the sample 1 is maintained low by which the exact mass spectrometry is accomplished.