الفهرس 
Theoretical BackgroundOnly 14 pages are availabe for public view
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Abstract
In this work we are interested in measuring the refractive index of some biogases (Methane, Nitrogen, Oxygen, and Sulfur hexafluoride). The measurement proceeded at different pressures range from 60 to 90 cm Hg and temperatures from 313 to 348 K. A Mach-Zehnder interferometer illuminated with (He-Ne) laser at 632.8 nm was used for measuring the refractive index and its variation with pressure and temperature. This method is based on shifting of the interference fringes pattern because of the change of the pressure (density) at constant temperature. Chapter 1 discusses the main dielectric properties of gases and their relation with the refractive index. Also, discusses spectroscopy and quantum chemical calculation of the selected gases. Chapter 2 describes the interference phenomena and the types of interference (multiple beam interference like Fabry-Berot interferometer and two- beam interference like Michelson, Rayleigh and Mach-Zehnder interferometer). ii Why we used Mach-Zehnder interferometer in this work for measuring the refractive indices of biogases as (Methane, Nitrogen, Oxygen, and Sulfur hexafluoride). Chapter 3 describes the constructed experimental tool to measure the refractive indices of gases as a function of pressure and temperature. Chapter 4 introduces the experimental results for the gases (Methane, Nitrogen, Oxygen, and Sulfur hexafluoride), and the theoretical calculations of these gases by using (Gaussian 09) program.