NEUTRALIZATION OF SAMPLE CHARGING IN SECONDARY ION MASS-SPECTROMETRY VIA A PULSED EXTRACTION FIELD

A technique has been developed for preventing surface charging of electrically nonconducting samples in secondary ion mass spectrometry (SIMS) when a negative ion or neutral primary beam (but not a positive ion primary beam) is used. Positive and negative particles are alternately extracted from the sample by rapidly reversing the polarity of the secondary Ion extraction voltage such that the emission of positive and negative charge is balanced and the sample remains neutral. The technique is nonintrusive, is applicable to all materials, and will permit the Interlaced acquisition of positive and negative secondary ion spectra. The technique is demonstrated with a static-SIMS static-SIMS Instrument utilizing a negative ion and neutral molecular primary beam. Both positive and negative secondary ion spectra of several highly nonconducting samples are shown. © 1990, American Chemical Society. All rights reserved.