Ultra-High Vacuum SIMS: A Pilgrim’s Journey Through History

Many people no doubt remember that Secondary Ion Mass Spectrometry (SIMS) contributed a great deal to the early days of the space age by playing a major role in the microanalysis of lunar rocks returned from the Apollo missions of the United States. By successfully using either argon or oxygen as the primary ion species, many applications focussed on the identification of oxides and other chemical states. SIMS has also been widely used to analyze ferrous and non-ferrous alloys required by heavy industry, in a period roughly starting around 1964. In these instances, a primary argon ion beam has been enhanced with a small oxygen jet or the actual primary beam used oxygen ions. In all of these techniques mentioned so far, the SIMS technique could be carried out without the need for an ultra-high vacuum (UHV) environment.