Browsing by Author "Seboka, Cherinet"

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    Determination of Optical Constants and Thickness of 3-Octylphenylthiophene/Popt by Rotating Angle Ellipsometry
    (Addis Ababa University, 2007-07) Seboka, Cherinet
    When a plane polarized light is reflected from the surface of an organic sample or thin film mounted on a glass substrate called Poly 3-Octylphemylthiophene/POPT at some different angles of incidence around the brewster angle of the sample in between 570 up to 610 ,then the reflected light which is elliptically polarized and its intensity is detected by photodetector.From its intensity curve the Fourier coefficients a and b are collected by fitting to Fast Non Linear Curve Fitting.Based on the Fourier Coefficients the ellipsometric angle , and the amplitude coefficients (Fresnel Coefficients) for parallel and perpendicular light rs and rp from the upper and bottom surface of the film are computed.From the ellipsometric angles and Fresnel coefficients the optical parameters of the sample such as refractive index, extinction coefficients and the film thickness are determine[5]