The present invention relates to energetic atomic beam generation, and particularly to electrically neutral molecular or atomic beam devices and methods for mass spectrometry and surface analysis, often called fast-atom bombardment mass spectrometry (FABMS).
FABMS has several advantages over secondary-ion mass spectrometry (SIMS). The primary advantage is that FABMS allows the use of a liquid matrix, which simplifies sample preparation and maintains a reservoir of undamaged molecular sample species when subjected to an atomic beam under dynamic (intense particle flux) conditions. Secondly, the use of a neutral atom beam in the FABMS avoids the problem of floating the ion gun system above the accelerating voltage of the spectrometer. Finally, sample charge buildup is reduced with this neutral particle bombardment.
Molecular SIMS is invaluable for the analysis and characterization of bulk solid surfaces, their films and molecular overlayers. The static (low particle flux) used in molecular SIMS is desirable to avoid damage to the molecular solid sample. Although conventional ion sources are capable of operation under such static conditions, attempts to charge neutralize the sample with an electron flood gun to avoid sample charge buildup are often ineffective, and they can result in bombardment-induced radiation damage and electron-stimulated desorption. The dynamic (intense particle) flux of conventional atomic beam sources quickly destroys the molecular overlayers or thin molecular film samples associated with the molecular SIMS method.