Secondary ion mass spectrometry

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This article describes a type of spectrometry; for the video games, see List of Sim games.

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. Fundamental for SIMS was pioneered by Herzog and Viehböck, 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 Münster by Benninghoven, Niehus and Steffens and also by Charles Evans & Associates (Redwood City, CA, USA).

Detection limits for most trace elements are between 10¹² and 10¹⁶ atoms per cubic centimeter. Achievable detection limits are highly dependent on the type of instrumentation used, the primary ion beam used and the analytical area, amongst other factors. Depending on the current (pulsed or continuous) and dimensions of the primary ion beam (often Cs⁺, O^- or Ga⁺) then the analysis may be extremely surface sensitive or could go very deep into the sample, eroding a crater in realtime.

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, usually with a pulsed ion beam and a time of flight mass spectrometer, while Dynamic SIMS is the process involved in bulk analysis, closely related to the sputtering process, using a DC primary ion beam and a magnetic sector or quadrupole mass spectrometer.

The COSIMA instrument on board of the Rosetta is the first instrument to determin the composition of cometary dust with secondary ion mass spectrometry.^[1]

[edit] See also

• SHRIMP

[edit] External links

• 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.
• SIMS workshop, site includes a literature database [1]

[edit] References

1. ^ C. Engrand, J. Kissel, F. R. Krueger, P. Martin, J. Silén, L. Thirkell, R. Thomas, K. Varmuza. "Chemometric evaluation of time-of-flight secondary ion mass spectrometry data of minerals in the frame of future in situ analyses of cometary material by COSIMA onboard ROSETTA". Rapid Communications in Mass Spectrometry 20: 1361-1368. DOI:10.1002/rcm.2448.