Secondary ion mass spectrometry
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- This article describes a type of spectrometry; for the video games, see List of Sim games.
Image:SIMS instrument scheme 600x600.png
The process known as secondary ion mass spectrometry (SIMS) involves bombarding the surface to be tested with a stream of ions. The test piece then emits particles, some of which are themselves ions. These secondary ions are measured with a mass spectrometer to determine the quantitative elemental or isotopic composition of the surface. SIMS is the most sensitive surface analysis technique, but is more difficult to accurately quantify than some other techniques.
The history of SIMS is largely developed in the book Secondary Ion Mass Spectrometry: Basic Concepts, Instrumental Aspects, Applications, and Trends: The first observation of ion-induced neutrals and positive ions was made by J.J.Thomson in 1910. Fundammental for SIMS was pioneered by Herzog and Viehboek, in 1949, at the University of Vienna, Austria. Two SIMS instruments were developed independently in the early 1960's. An American project, led by Liebel and Herzog was sponsoreed by the NASA at GCA Corp, Massachusetts, with the target of analyzing moon rocks. A French project was initiated at the University of Orsay by Raimond Castaing in the framework of the PhD thesis of Georges Slodzian. Both instruments were further manufactured respectively by GCA Corp and Cameca, in the Paris area which is still involved SIMS instrument in 2005. These first instruments were based onto a magnetic double focusing mass spectrometer. In the earliest 1970's, SIMS instruments were developed with Quadrupole spectrometers, firstly by Alfred Benninghoven at the University of Munster, Germany and K.Wittmack in the Munich area. In the earliest 1980's SIMS Instruments based on Time of Flight spectrometers were developed at the University of Munster by Benninghoven, Niehus and Steffens.
Detection limits for most trace elements are between 1012 and 1016 atoms per cubic centimeter. Because the primary beam erodes the surface, a depth profile (e.g., 1 micrometer deep) may be obtained from a time trace. The lateral resolution is determined by the width of the primary beam and can be better than 50 nanometers.
In the field of Surface Analysis, it is usual to distinguish Static SIMS and Dynamic SIMS. Static SIMS is the process involved in surface atomic monolayer analysis, while Dynamic SIMS is the process involved in bulk analysis, closely related to the sputtering process.
See also
Evans Analytical Group has excellent tutorial pages for SIMS theory and instrumentation, where the book Secondary Ion Mass Spectrometry: Basic Concepts, Instrumental Aspects, Applications, and Trends, by A. Benninghoven, F. G. Rüdenauer, and H. W. Werner, Wiley, New York, 1987 (1227 pages), is cited as "the best SIMS reference". For a presentation describing Time of Flight SIMS see TOF SIMS presentation.it:Spettrometria di massa di ioni secondari ja:二次イオン質量分析法