G‐SIMS: relative effectiveness of different monatomic primary ion source combinations

Abstract

An analysis is made of the characteristics of monatomic primary ion sources to generate G-SIMS (gentle SIMS) spectra. In previous studies, this is resolved into the parameter beta that describes the relative intensities of ions in the series C(n)H(n+2-i) as i changes. For this, data from polystyrene are most extensive. It is found that the experimental beta values, which relate to the emitted secondary ion fragment surface plasma temperatures, are accurately described by an empirical fit involving the ratio of the sputtering yield and the mass of the primary ion. This description covers data for Ar(+), Bi(+), Cs(+), Ga(+), Mn(+) and Xe(+) monatomic primary ions with energies in the range 4 to 25 keV, placing them in a coherent framework, and permits the performance of any other monatomic primary ion to be predicted. This shows that, of all monatomic primary ions, Bi will yield the highest beta values and Mn the lowest. Since the G-SIMS spectra are ratios, a ratio involving spectra using these primary ions gives the maximum signal quality possible and these are therefore recommended for use. The previous choice of these ions for a combined G-SIMS source, based on practical considerations, is thus shown to be optimum.

Universal Equation for Argon Cluster Size-Dependence of Secondary Ion Spectra in SIMS of Organic Materials

“…In 2000, Gilmore and Seah established the G-SIMS technique 5 which showed that the spectra for different primary ion sources were related and that the way that spectra changed from source-to-source depended on the source and its ion impact energy. 6 Later, it was shown 7 that secondary ion spectra from Irganox 1010 for Ar + , Bi + , Bi 3 + , and Bi 5 + primary ion sources could all be related, over many orders of magnitude, to an accuracy of 2.3% for 389 fragment peaks. These spectra involved the product of just two spectra, one representing a low degree of fragmentation and one a high degree.…”

Cluster Primary Ion Sputtering: Secondary Ion Intensities in Static SIMS of Organic Materials

“…Thus, if the intensity ratios, F 12,i of two spectra, I(1,m/z) and I(2,m/z) were plotted, it was seen that the data exhibit linear regions when F 12,i is plotted on a log 10 scale. This was interpreted to show that 21,22 where β* is given by † Part of the Barbara J. Garrison Festschrift. * To whom correspondence should be addressed.…”

“…Studies using many different primary ions have been made using polystyrene, (CH 2 -CHPh) q , where Ph is a pendant phenyl ring and q shows the number of repeat groups or the degree of polymerization. 21,23 The spectra are referenced to that for argon at 7 keV beam energy and values of β () 0.431β*) 22 can then be measured. In polystyrene, in the mass range 12 e m/z e 160 u, for which 1 e j e 12 and for 0 e i e 10, it is found that β is effectively constant.…”

Water‐Soluble Self‐Assembled Butadiyne‐Bridged Bisporphyrin: A Potential Two‐Photon‐Absorbing Photosensitizer for Photodynamic Therapy

“…The G‐SIMS spectra are then generated as where g , the g index, was originally taken as 13 63. Elsewhere, we show how the different monatomic primary ions may be ranked for their efficiency in generating G‐SIMS spectra 79. Good primary ions for the low d E /d x spectrum are Ar + , Ga + and Mn + and for the high dE/dx spectrum, Bi + and Au + , with Cs + , In + and Xe + being useful intermediate primary ions.…”