Page 202 - Inorganic Mass Spectrometry - Fundamentals and Applications

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Energy distribution of Al+, A1 l,+ ions sputtered from aluminum tar-
get. An energy window of 4 eV was used. (From Ref. 85,)

attempts at ~uanti~cation based on various theories of sputtering and ion foma-
tion have met with limited success. The use of standards and relative sensitivity
factors for calibration of instruments and procedures has proved more successful.
Each of these is discussed briefly.
The ion yield Si (ions per incident ion) of element i in a sample matrix M
under ion bombard~ent may be expressed as
si = aiCiYM (4.2)

where a is the ratio of the secondary ions of element i to the total number of i
atoms sputtered. Ci is the atomic concentration of i in the sample. YM is the total
sputter yield of the sample. The secondary ion current, I, of isotopej of element i
is given by