Scanning electron microscopy film thickness

Concerning the two-layer model, the thickness and properties of each layer depend on the nature of the electrolyte and the anodisation conditions. For the application, a permanent control of thickness and electrical properties is necessary. In the present chapter, electrochemical impedance spectroscopy (EIS) was used to study the film properties. The EIS measurements can provide accurate information on the dielectric properties and the thickness of the barrier layer [13-14]. The porous layer cannot be studied by impedance measurements because of the high conductivity of the electrolyte in the pores [15]. The total thickness of the aluminium oxide films was determined by scanning electron microscopy. The thickness of the single layers was then calculated. The information on the film properties was confirmed by electrical characterisation performed on metal/insulator/metal (MIM) structures. 

Pore dimensions may have a more subtle effect on decay rate depending on component dimensions and production method of the manufactured material. Products made from pasted starch, LDPE, and EAA (2) typically appeared as laminates of starch and plastic when examined by scanning electron microscopy (Figure 1). The dimensions of inter-laminate channels (i.e., pores) were not uniform and ranged from about 50 to 325 m in cross-section (22). Since flux is dependent on diffusional path area, the smaller pores can be an impediment to movement of solutes from the interior to the surface of the films. Figure 5 illustrates two films in which the laminate units are the same thickness, but differ in length. When the starch is removed... 

Bond failure may occur at any of the locations indicated in Fig. 1. Visual determination of the locus of failure is possible only if failure has occurred in the relatively thick polymer layer, leaving continuous layers of material on both sides of the fracture. The appearance of a metallic-appearing fracture surface is not definite proof of interfacial failure since the coupling agent, polymer films, or oxide layers may be so thin that they are not detectable visually. Surface-sensitive techniques such as X-ray photoelectron spectroscopy (XPS) and contact angle measurements are appropriate to determine the nature of the failure surfaces scanning electron microscopy (SEM) may also be helpful if the failed surface can be identified. 

HPC (Klucel E5, Hercules hydroxypropyl molar substitution, MS-3) and HPMC (Methocel E15, Colorcon hydroxypropyl molar subsitution, MS-0.23s degree of methoxyl substitution DS-1.88) were studied as a thin film of approximate thickness of 5-10 urn cast from an aqueous solution onto a clean aluminium substrate and allowing the solvent to evaporate. Scanning electron microscopy of films prepared in this manner revealed a continuous surface free from cracks and aberrations. 

The structures of the thick anodic and cathodic films produced from the working solutions with active additives and without them as well as the structure of the thin anodic film deposited from the TFE solution have been studied using scanning electron microscopy. The thin anodic film produced from the TFE solution without additives (Fig. 2, a) is porous and consists of small crystals. The... 

The ellipsometry analysis indicated that the thickness of film 1 was fairly uniform, giving an average of 2168 A. Scanning electron microscopy (SEM) showed that the film was smooth. No pattern was observed in powder X-ray diffraction of the film, indicating that the film was amorphous, a desired feature of diffusion barriers. 

The surface morphology, thickness and quality of the deposited carbon films are analyzed by scanning electron microscopy (SEM), by energy dispersive x-ray (EDx) and by Raman spectroscopy (RS). The Raman spectrum was recorded using an argon ion laser Raman microprobe. The exciting laser wavelength is 632.81 nm with a laser power equal to 1.75 mW. The instrument was operated in the multi-channel mode with the beam focused to a spot diameter of approximately 2 pm. 

As new membranes are developed, methods for characterization of these new materials are needed. Sarada et al. (34) describe techniques for measuring the thickness of and characterizing the structure of thin microporous polypropylene films commonly used as liquid membrane supports. Methods for measuring pore size distribution, porosity, and pore shape were reviewed. The authors employed transmission and scanning electron microscopy to map the three-dimensional pore structure of polypropylene films produced by stretching extended polypropylene. Although Sarada et al. discuss only the application of these characterization techniques to polypropylene membranes, the methods could be extended to other microporous polymer films. Chaiko and Osseo-Asare (25) describe the measurement of pore size distributions for microporous polypropylene liquid membrane supports using mercury intrusion porosimetry. 

The electrical properties of the films were determined on aluminium/insu-lator/gold (MIM) structures. The capacitance was measured with a LCR Meter (Agilent 4284 A) at a frequency of 1 kHz. The specific resistance and the breakdown field strength were measured using a Source-Measure-Unit (SMU, Keithley 6430). The film thickness was determined by scanning electron microscopy (SEM). 

Samples for transmission electron microscopy were prepared in the following manner. Films were grown with different current rates up to various thicknesses on platinum working electrodes. The film thickness was controlled by the period of current flow. The films were transferred onto carbon coated electron microscope grids by stripping with formvar and subsequently removing the formvar with methylene chloride. As-synthesized films were directly used for scanning electron microscopy. 

To understand the release mechanism, cryomicrotomy was used to slice 10 m-thick sections throughout the matrices. Viewed under an optical microscope, polymer films cast without proteins appeared as nonporous sheets. Matrices cast with proteins and sectioned prior to release displayed areas of either polymer or protein. Matrices initially cast with proteins and released to exhaustion (e.g., greater than 5 months) appeared as porous films. Pores with diameters as large as 100 /xm, the size of the protein particles, were observed. The structures visualized were also confirmed by Nomarski (differential interference contrast microscopy). It appeared that although pure polymer films were impermeable to macromolecules (2), molecules incorporated in the matrix dissolved once water penetrated the matrix and were then able to diffuse to the surface through pores created as the particles of molecules dissolved. Scanning electron microscopy showed that the pores were interconnected (7). 

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