Chemistry, surface changes

In summary, these SIMS studies have shown that reproducible measurements of some surface chemistry changes are possible following very early attack of glass surfaces by water. Early depletions of sodium and more surprisingly, boron, are indicated even after a few minutes of leaching time. The apparent effects of surface hydration on the SIMS relative ion yields also warrants further investigation. 

Successfully developing a surface engineering strategy based on surfactant behavior at interfaces requires surface characterization techniques that can validate and quantify surface chemistry changes. This review describes the role of two surface chemistry analysis techniques that have proven highly successful in surfactant analysis x-ray photoelectron spectroscopy (XPS) and static secondary ion mass spectrometry (SSIMS). In Section II, the methods by which these techniques analyze surface chemistry are described. In Section III, recent examples of their application in surfactant-based surface engineering are described. 

The chemical modification of alumina both by alkali and acid leads to the textural as well as surface chemistry changes on the surface of alumina. The total Lewis acidity and Bronsted acidity and basicity are altered to the desired levels. The textural changes like surface area and pore size distribution can be deduced from the adsorption and desorption of N2 at 77K on the four alumina samples. The surface area calculated by BET method for the four adsorbents is given in Table 3. 

N.M. Stark and L.M. Matuana, Surface chemistry changes of weathered HDPE/wood-flour composites studied by XPS and FTIR spectroscopy. Polym. Degrad. Stabil. 86, 1-9 (2004). 

Ducheyne, P. and Healy, K., "Titanium Immersion-Induced Surface Chemistry Changes and the Relationship to Passive Dissolution and Bioactivity, The Bone-Biomaterial Interface, J. E. Davies, Ed., University of Toronto Press, 1991, pp. 62-67. 

The results presented in this chapter demostrated that the minimum amount of carbon needed to achieve a specific mercury removal efficiency by sorbent injection into a flue gas stream can be predicted by assuming mass transfer limitations. Mercury removal effectiveness can be increased by decreasing the size of the carbon injected, increasing the residence time, or the amount of carbon injected. If mercury removal is limited by the reactivity and capacity of the carbon (i.e. not mass transfer limited), then significantly more carbon than the amount predicted by mass transfer limitations may be needed for effective mercury removal unless the reactivity and capacity of the carbon can be improved through structural and surface chemistry changes. Intraparticle diffusion is not important because of the small carbon sizes normally used for injection. 

Ellipsometiy is another common technique in the semiconductor industry. It provides an accurate measure of the film thickness. Since many resist shrink iqx>n deprotection due to a loss of volatile components, ellipsometry has been used do monitor the extent of deprotection in the resist. However, the technique does not provide direct infotmation about chemical bonding. Fourier transform infiared (FTIR) spectroscopy provides die best detail about chemical bonding, however it is a bulk technique widi little surfiice sensitivity. Moderate surface sensitivity can be achieved by utilizing total internal reflection FTIR, however the evanescent field will still propagate 500 nm away fix>m die surface making it difficult to detect true surface chemistry changes in a resist film. 

Stark, N.M., Matuana, D.P. Surface chemistry changes of weathered HDPE/wood-flour composites studied by XPS and ETIR spectroscopy. Polym. Degrad. Stab. 86, 1-9 (2004) Stark, N.M., Matuana, L.M. Surface chemistry and mechanical property changes of wood-flour/high-density-polyethylene composites after accelerated weathering. J. Appl. Polym. Sci. 94, 2263-2273 (2004)... 

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