Surface and Thin Film Characterization

A very common and useful approach to studying the plasma polymerization process is the careful characterization of the polymer films produced. A specific property of the films is then measured as a function of one or more of the plasma parameters and mechanistic explanations are then derived from such a study. Some of the properties of plasma-polymerized thin films which have been measured include electrical conductivity, tunneling phenomena and photoconductivity, capacitance, optical constants, structure (IR absorption and ESCA), surface tension, free radical density (ESR), surface topography and reverse osmosis characteristics. So far relatively few of these measurements were made with the objective of determining mechanisms of plasma polymerization. The motivation in most instances was a specific application of the thin films. Considerable emphasis on correlations between mass spectroscopy in polymerizing plasmas and ESCA on polymer films with plasma polymerization mechanisms will be given later in this chapter based on recent work done in this laboratory. 

Some of the modern surface analysis methods have been used to study the surface chemistry of both plasma etched surfaces and plasma polymerized thin films. Much of this work has involved exposure of these surfaces to air as the samples are transferred from the plasma system to the surface analysis system. However, in a few cases surface analysis has been performed in the plasma system after the plasma gas has been pumped away. This work will be discussed in more detail later in this chapter. 

---

The contributions of this volume were presented at the meeting and selected for publication in Progress in Colloid and Polymer Science covering a representative spectrum of surface sensitive techniques and their application to polymer surface and thin film characterization as well as recent examples of technologically relevant materials and process development. 

Also of interest to electrochemistry is SIMS, which is another ex situ UHV method for surface and thin-film characterization (93, 103, 128, 129). This approach involves the bombardment of a surface with a high-energy primary ion beam (e.g., 15 keV Cs" ), which etches the surface by sputtering and produces secondary ions derived from the sur-... 

Vol. 144. Surface-Launched Acoustic Wave Sensors Chemical Sensing and Thin-Film Characterization. By Michael Thompson and David Stone... 

Macrocyclic Compounds in Analytical Chemistry. Edited by Yury A. Zolotov Surface-Launched Acoustic Wave Sensors Chemical Sensing and Thin-Film Characterization. By Michael Thompson and David Stone Modern Isotope Ratio Mass Spectrometry. Edited by T. J. Platzner High Performance Capillary Electrophoresis Theory, Techniques, and Applications. Edited by Morteza G. Khaledi... 

Nonlinear optical techniques are extremely useful in characterizing the chiral properties of materials, as is pointed out by Verbiest and Persoons in Chapter 9. These authors give an in-depth discussion of this tool, both from an experimental and theoretical point of view, paying special attention to the characterization of chiral surfaces and thin films. In the second part of their contribution they highlight the role chiral materials can play in the field of nonlinear optics and photonics, which opens the way for a variety of applications. 

In Chapter 13 we discussed methods available for the characterization of surfaces and thin films. These were shown to be of practical importance mainly before and/or after the plating process. It is no less important to discuss the methods that are available to characterize, study, understand, and thus control the plating operation in situ that is, while the plating process is taking place. 

Thompson M, Stone DC (1997) Surface-launched acoustic wave sensors chemical sensing and thin-film characterization. Wiley, New York... 

Considerable progress has been made in studying tribofilms in the last decade. A number of important surface and thin film techniques have been developed in recent years, which are contributing to a better understanding of at least some tribochemical processes of boundary lubrication. In recent years, X-ray absorption near edge structure XANES spectroscopy, a powerful technique for tribofilm characterization, was used to identify a layered structure (surface and bulk) of tribofilms. The chemistry of tribofilms generated by the combination of zinc dialkyldithiophosphate (ZDDP) and molybdenum dialkyldithiocarbamate (MoDTC) has been examined. 

Characterization of surfaces and thin films has been revolutionized by the invention of scanning probe microscopes, i,e, scanning force microscopy, scanning tunnelling microscopy, and scanning near field optical microscopy [262-264], These methods not only allow imaging of molecular and supramolecular details, but can also be employed to probe and to manipulate chemical properties on a nanoscopic or molecular scale, e,g., mechanical SFM [265], chemical SFM [266], electrochemical STM [267,268],... 

As we mentioned, oxide surfaces are important in the field of nanocatalysis by supported metals. In practical applications, the support has the crucial role of stabilizing small metallic particles, which act as the actual catalysts in a chemical process. Once the oxide surface is sufficiently well characterized, one can deposit small metal clusters and study their reactivity as a function of the support, of the metal, of the size of the cluster, etc. In this way, complex catalytic processes can be divided into a series of substeps, which allow a more detailed microscopic characterization. Despite the fact that only recently well-defined metal clusters have been deposited under controlled conditions on oxide surfaces and thin films, great advances have been obtained in the understanding of the mechanisms of adhesion and growth of the metal particles to the oxide surface. In this process, the role of theory is quite substantial. 

Thompson M. and Stone D. C., Surface-launched Acoustic Wave Sensors (Chemical Sensing and Thin-Film Characterization) (New York John Wiley and Sons, 1997). 

---