Reflection ellipsometry

Reflectance ellipsometry is concerned with the measurement of the polarizing properties of an interface, i.e., with the measurement of tanif) and A, or of (R /R ) for the "clean" and covered surface. Defining the elliJBsometric reflectance absorbance according to... 

Fig. 4.2. The schematic experimental setup for reflection ellipsometry. The light from the laser source is guided through the polarizer (P) and PEM with its optical axis at an angle of 45° with respect to the direction of the polarization. The light beam is reflected from the lower side of the prism and is detected after passing through the analyzer, which is crossed with respect to the analyzer. DC, 1st and 2nd harmonic of the modulated light intensity are simultaneously measured, using the lock-in amplifier and computer for data acquisition. The prism has been used to eliminate parasite reflection from the air-glass interface. The x axis is parallel to the s polarization of light.

The state of polarization of light, reflected from an interface, depends strongly on the profile of the dielectric constant across that interface. This simple principle is used in the Brewster angle reflection ellipsometry (BAE), where one measures the ellipticity coefficient of light, reflected from an interface. The method is sensitive enough to detect extremely small changes in the structure of liquid crystalline-solid interfaces. Subnanometer resolution of the adsorption parameter is routinely achieved. The method is therefore very useful for the study of liquid crystal interfaces, where the surface-induced variation of the order can be observed [5,25,33-41]. 

UV-Visible Spectroscopy of Surface Species Specular Reflectance, Ellipsometry, Internal Reflection, and Waveguides... 

The progress in this area is, to a significant degree, linked to the exploitation of specialized experimental techniques such as neutron reflection, ellipsometry, fluorescence... 

The optical constant such as refractive index, and the thickness of a film are determined by ellipsometry. For polymer thin films the reflection ellipsometry technique is commonly used. This technique is especially useful in the wavelength regions where the materials are strongly absorbing so that the transmission measurements are precluded. 

Neuschaefer-Rube U., Hozapfel W., Wirth F. Surface measurement applying focusing reflection ellipsometry configurations and error treatment. Measurement 2003 33 163-171... 

This chapter summarizes the optical principles involved in ellipsometry and reviews some typical applications in electrochemical systems. Newly developing areas of application and recent developments in the experimental approach and instrumentation will also be dealt with. Some emphasis will be on modified techniques, including the combined reflectance-ellipsometry method. Ellipsometry is a broad field that includes various techniques and a wide range of applications. The chapter is mostly devoted to showing what can be done with ellipsometry for the purpose of investigating electrochemical interfaces. Readers are referred to other sources of information on specific subjects. A thorough treatment of polarized light and ellipsometry has been published by Azzam and Bashara. The technique as applied to electrochemistry has also been subject to various reviews " and symposia. 

Combined Reflectance-Ellipsometry (Three-Parameter Ellipsometry) Method... 

The optical principles and equations used in the technique are concisely summarized. The combined reflectance-ellipsometry (three-parameter ellipsometry) method and spectroscopic ellip-sometry are expected to be applied to an increasing number of studies in interfacial electrochemistry. The importance of proper experimental conditions, especially the proper choice of incidence angle is emphasized. Instrumentation, experimental methods, and error and sensitivity problems are dealt with. Some typical and recent applications in electrochemistry are reviewed. 

In general, Ss f Sp, and therefore if the incident linearly polarized wave, has both s- and p-components, the reflected wave is elliptically polarized. The parameters of the polarization ellipse are determined by the optical constants of both media and can be measured with high accuracy. This principle forms the basis of reflection ellipsometry (see Section 5.1). For historical reasons one often represents the ratio of the reflection coefficients, p, in terms of the ellip-sometric angles, Y and A, as... 

Although there are many methods available to determine e(ar) for a crystal from spectra of transmissivity, external reflection, ellipsometry, etc., they are in general nonversatile and useful only for a limited range of optical constants. The advantage of surface polariton spectroscopy is that it provides a direct... 

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