In my opinion and from my experience in Surface analysis techniques I think in this particular case to determine the full surface coverage of silane, would be recommended to use a method or technique of high surface sensitivity , ie a high-resolution in depth technique.

More than lateral or spatial resolution, it is necessary to have a technique that provides in-depth information and the depth of analysis should be less than the typical thickness of the silane layer. Since the analysis depth of the TOF-SIMS also called Static SIMS (S-SIMS) is approximately a nanometer, the technique is particularly suitable for this type of analysis. As already discussed previously Professor Sebastian Feliu, also the technique of angle-resolved XPS (AR-XPS), could be used successfully.

Furthermore, the TOF-SIMS technique is capable of providing molecular information that will help in this particular case.

Why is necessary a high resolution in depth?

Considering the layer is uniformly and homogeneously distributed on the substrate and covers the entire surface, if the technique employed, extracts information from areas of greater depth than the silane layer itself, will be detected signals from the substrate, but not necessarily are due to a lack of the layer on the surface, but because the technique extract information from more depth than the desirable depth or volume, with the added difficulty that both layer and substrate share elements in its composition as silane and silicon oxide from the substrate.

There are published studies, using TOF-SIMS and other surface analysis techniques as XPS(X-Ray Photoelectron Spectroscopy), AES (Auger Electron Spectroscopy) and ISS (Ion Scattering Spectroscopy) for the study of various materials and surfaces modified with silanes, which could be of great help, I indicate some references I founded:

1) A dissertation from the University of Uppsala: Surface Characterisation Using

ToF-SIMS, AES and XPS of Silane Films and Organic Coatings Deposited on Metal Substrates. You can access this document freely through the following link: http://uu.diva-portal.org/smash/get/diva2:162811/FULLTEXT01

2) Characterization of films of Organofunctional silanes by TOFSIMS and XPS

Journal of Adhesion Science and Technology Volume 5, Issue 10, 1991

3) Estimation of Silane Functionalized Coverage perfluoropolyether

Layer by using Time of Flight Secondary Ion Mass Spectrometry,

Atomic Force Microscopy and Ion Scattering Spectroscopy Journal of Surface Analysis, Vol.12 No.2 (2005)

4)Characterization of films of organofunctional silanes by ToF-SIMS. Part II. Films of γ-APS, AEAPS and FPS on cold-rolled steel and cold-rolled zinc substrates†

Surface and Interface Analysis

Volume 20, Issue 5, pages 475–484, 15 May 1993

5)Time-of-flight SIMS characterization of hydrolysed organofunctional and non-organofunctional silanes deposited on Al, Zn and Al–43.4Zn–1.6Si alloy-coated steel

Surface and Interface Analysis

Volume 35, Issue 11, November 2003, Pages: 880–887,

I hope it can help

In my opinion and from my experience in Surface analysis techniques I think in this particular case to determine the full surface coverage of silane, would be recommended to use a method or technique of high surface sensitivity , ie a high-resolution in depth technique.

More than lateral or spatial resolution, it is necessary to have a technique that provides in-depth information and the depth of analysis should be less than the typical thickness of the silane layer. Since the analysis depth of the TOF-SIMS also called Static SIMS (S-SIMS) is approximately a nanometer, the technique is particularly suitable for this type of analysis. As already discussed previously Professor Sebastian Feliu, also the technique of angle-resolved XPS (AR-XPS), could be used successfully.

Furthermore, the TOF-SIMS technique is capable of providing molecular information that will help in this particular case.

Why is necessary a high resolution in depth?

Considering the layer is uniformly and homogeneously distributed on the substrate and covers the entire surface, if the technique employed, extracts information from areas of greater depth than the silane layer itself, will be detected signals from the substrate, but not necessarily are due to a lack of the layer on the surface, but because the technique extract information from more depth than the desirable depth or volume, with the added difficulty that both layer and substrate share elements in its composition as silane and silicon oxide from the substrate.

There are published studies, using TOF-SIMS and other surface analysis techniques as XPS(X-Ray Photoelectron Spectroscopy), AES (Auger Electron Spectroscopy) and ISS (Ion Scattering Spectroscopy) for the study of various materials and surfaces modified with silanes, which could be of great help, I indicate some references I founded:

1) A dissertation from the University of Uppsala: Surface Characterisation Using

ToF-SIMS, AES and XPS of Silane Films and Organic Coatings Deposited on Metal Substrates. You can access this document freely through the following link: http://uu.diva-portal.org/smash/get/diva2:162811/FULLTEXT01

2) Characterization of films of Organofunctional silanes by TOFSIMS and XPS

Journal of Adhesion Science and Technology Volume 5, Issue 10, 1991

3) Estimation of Silane Functionalized Coverage perfluoropolyether

Layer by using Time of Flight Secondary Ion Mass Spectrometry,

Atomic Force Microscopy and Ion Scattering Spectroscopy Journal of Surface Analysis, Vol.12 No.2 (2005)

4)Characterization of films of organofunctional silanes by ToF-SIMS. Part II. Films of γ-APS, AEAPS and FPS on cold-rolled steel and cold-rolled zinc substrates†

Surface and Interface Analysis

Volume 20, Issue 5, pages 475–484, 15 May 1993

5)Time-of-flight SIMS characterization of hydrolysed organofunctional and non-organofunctional silanes deposited on Al, Zn and Al–43.4Zn–1.6Si alloy-coated steel

Surface and Interface Analysis

Volume 35, Issue 11, November 2003, Pages: 880–887,

I hope it can help

Dear Sebastian:

It will be a pleasure to collaborate with you.

Regarding the TOF-SIMS, I think is a very powerful technique that offers possibilities, which are not possible with other surface analysis techniques, such as high resolution in depth much better than the XPS, the ability to provide molecular information , parallel detection (not sequential as in the case of XPS) and excellent detection limit.

But of course all techniques have strengths and weaknesses, so that not everything is perfect, that's why I always advocate for the complementary character of the surface analysis techniques and for that reason, in our service we have more than one of these techniques.

In the case of TOF-SIMS one of the weaknesses of the technique is the difficulty to perform quantification ( in XPS, is much more intuitive, although we know that also involves complexities and difficulties, it is possible to approach values ​​closer to the reality of the material more easily, at least on the order of magnitude)., in the case of TOF-SIMS is difficult due to matrix effects, and the need for reference materials (standards). Also the analysis of the results is more complex especially in the case of products of organic origin.

Many of the TOF-SIMS users also use the XPS to analyze their material because the complementarity of both techniques provides a comprehensive look at the surface.

It is true that this technique is not as widespread as the XPS, and therefore but it is a much newer techniqueand therefore is not as popular as XPS or AES.

Every year manufacturers improve equipment, designing new developments that enhance and extend its capabilities.

I hope that in the future you have the opportunity to evaluate the potential of TOF-SIMS.

Regards