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Studying the Molecular Dynamics of Deuterium Molecules Trapped Inside a Simple Clathrate Hydrate Using High Resolution Raman Spectroscopy

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Studying the Molecular Dynamics of Deuterium Molecules Trapped Inside a Simple Clathrate Hydrate Using High Resolution Raman Spectroscopy American University in Cairo AUC Knowledge Fountain Theses and Dissertations 2-1-2014 Studying the molecular dynamics of deuterium molecules trapped inside a simple clathrate hydrate using high resolution Raman spectroscopy Mohamed Ibrahim Moussa Ibrahim Follow this and additional works at: https://fount.aucegypt.edu/etds Recommended Citation APA Citation Ibrahim, M. (2014).Studying the molecular dynamics of deuterium molecules trapped inside a simple clathrate hydrate using high resolution Raman spectroscopy [Master’s thesis, the American University in Cairo]. AUC Knowledge Fountain. https://fount.aucegypt.edu/etds/1284 MLA Citation Ibrahim, Mohamed Ibrahim Moussa. Studying the molecular dynamics of deuterium molecules trapped inside a simple clathrate hydrate using high resolution Raman spectroscopy. 2014. American University in Cairo, Master's thesis. AUC Knowledge Fountain. https://fount.aucegypt.edu/etds/1284 This Thesis is brought to you for free and open access by AUC Knowledge Fountain. It has been accepted for inclusion in Theses and Dissertations by an authorized administrator of AUC Knowledge Fountain. For more information, please contact [email protected]. The American University in Cairo School of Sciences & Engineering "Studying the Molecular Dynamics of Deuterium Molecules trapped inside a Simple Clathrate Hydrate Using High Resolution Raman Spectroscopy" A Thesis submitted to The Physics Graduate Program In partial fulfillment of the requirements for the degree of Master of Science By Mohamed I. Mousa Supervisor: Prof. Salah El.Sheikh Physics Department, The American University in Cairo Co-Advisors: Dr. Lorenzo Ulivi, Dr. Milva Celli Institute of Complex Systems, National Research Center, Florence, Italy September 2013 DEDICATION "I dedicate this research to the all innocent people that died in Egypt at the last events followed ousting of Mohamed Morsi, especially, my friends Habiba Ahmed Abdel Aziz and Abdel Hameed Sobeah" II ACKNOWLEDGEMENTS Thanks to Allah for all his support in my life. Thanks to my parents for your continuous encourage and help to finish this dissertation. Without you, nothing would be done. I promise I will always make you proud of me. To Dr. Salah El-Sheikh, you have assisted me to join the program, to pursue my experimental work in Italy. Without your guidance and persistence help this dissertation would not have been possible. You are my godfather. To Dr. Lorenzo Ulivi and Dr. Milva Celli, you have hosted me in your laboratory, allowed me to use your equipment, taught me how to be a good experimentalist, and helped me to analyze the experimental data. It is a pleasure for me to know you and to work with you. To Moaaz El Ghazaly, you are the best companion. We have experienced every moment in our careers together. Hope that if we can get the PhD together. To Mohamed Zaghloul, thank you for your information that you have provided. Without you, the stay in Italy would be harder. Great thanks to my colleagues and friends in physics department. It was a pleasure for me to work, laugh, discuss III with you. You have helped me a lot and I will never forget you. To my sisters Mona and Maha, thanks a lot for your patience, love, and kindness. Especial thanks to Mona for lending me her laptop. Thanks to my fiancée, Yasmin, that encouraged me to do this research. You have afforded my hard times. Without your motivation, the thesis will take more time to be finished. Thanks to Yasmin's family, Nevin, Hisham, uncle Ezzat, aunt Taghred, for your solid support. Thanks to the all people that help me to get this final form of the thesis. IV ABSTRACT As the energy resources running out, scientists are trying to provide sustainable energy. They move toward the hydrogen economy although it has large technical difficulties that need to be solved. Hydrogen is considered as a clean fuel. Storing hydrogen using clathrate hydrates is one of the promising ways to provide required energy. The high hydrogen content in sII clathrate hydrate proposes some applications like replacing gasoline to fuel vehicles, using as a gas separation substance, and transporting some dangerous gases. In addition, clathrate hydrate is found in nature in huge amounts. Generally speaking, it is approximated that about 3000 billion tons of carbons of clathrate hydrates exist as a worldwide reserves. This large amount can replace usual fossil fuel like oil and coal, and be a new energy source. All what we need is to investigate these compounds and find the ways to make use of them. Clathrate hydrates are inclusion compounds, physically resembles ice, can trap a guest small non polar molecule behind walls made by water via confining the guest molecules by a definite structure. So, it isn’t a chemical storage but physical. From the historical point of view, it is thought that the hydrogen and its isotopes are very small to make clathrate compounds stable but, recently, it is used to build a simple cubic structure II with water molecules. Formation of clathrate hydrates depends on the applied high pressure, low temperature, and the guest molecule. In this research, a full detailed picture of deuterium clathrate hydtare including structure, occupancy number per cage, deuterium dynamics, and ortho-para conversion of deuterium inside the cages has been conducted. The storage of deuterium in clathrate hydrate has been tested, and basal concepts of enclathrated deuterium have been evaluated. Manifold cavity occupation and small inter-molecular separation are some new exciting aspects. The small V cages of sII structure can contain one deuterium molecule which represents deuterium content of 1.0 wt%. Raman spectroscopy is an important tool to study the dynamics of the trapped deuterium and the occupancy of deuterium inside the cages of the clathrate hydrate. It shows the vibrational and rotational bands of deuterium molecules. In sII hydrates, we have two types of cages: small cages and large cages. Enclathrated deuterium at all cages vibrates at lower frequency than free gas phase. In addition, the single deuterium occupied cages vibrates at lower frequency than multiple deuterium occupied cages. Raman spectra was collected from many samples of in-situ prepared deuterium clathrate placed in a cell to see the formation of the clathrate structure and the changes occur while applying heating and quenching cycles. Analysis of the vibrational bands of different cages has been explored and calculations regarding average occupancy number have been done. VI TABLE OF CONTENTS Chapter 1 INTRODUCTION TO CLATHRATE COMPOUNDS, CLATHRATE HYDRATES AND HYDROGEN CLATHRATES .................. 1 1.1 Clathrate Compounds ................................................................................ 1 1.2 Clathrate Hydrates..................................................................................... 2 1.3 Hydrogen Clathrates ................................................................................. 8 1.3.1 Hydrogen Hydrates as Future Fuel .............................................. 15 1.4 Hydrate Formation and Dissociation Processes ...................................... 16 1.5 Thesis Objectives and Outline ................................................................ 19 Chapter 2 THE THEORY OF RAMAN SPECTROSCOPY ........................... 20 2.1 Raman Spectroscopy ............................................................................... 20 2.2 Classical Theory of Raman Scattering .................................................... 25 2.3 Quantum Particle Explanation of Raman Scattering .............................. 30 2.4 The Quantum Agreement with the Classical Theory and Experimental Data ............................................................................................................... 36 Chapter 3 RAMAN SPECTROSCOPIC STUDIES OF HYDROGEN CLATHRATES ................................................................................................. 38 3.1 Introduction ............................................................................................. 38 3.2 Analysis of the Rotatinal Modes using Raman Spectroscopy ................ 38 3.2.1 Ortho-Para Conversion .................................................................. 43 3.3 Analysis of the Vibrational Modes using Raman Spectroscopy ............. 49 3.3.1 Vibrational Modes of H2 ................................................................ 49 3.3.2 Vibrational Modes of D2 ................................................................ 56 VII Chapter 4 THE EXPERIMENTAL PROCEDURE AND ANALYSIS OF RAMAN SPECTRUM OF SIMPLE sII DEUTERIUM CLATHRATE HYDRATES ..................................................................................................... 61 4.1 Equipment and Experimental Procedure ................................................ 61 4.1.1 Setup of the Cell ............................................................................. 62 4.1.2 Optical Path Setup ......................................................................... 69 4.1.3 Procedure ........................................................................................ 74 4.2 Results and Data analysis ........................................................................ 76 4.3 Conclusion .............................................................................................. 84 Chapter 5 APPLICATIONS AND RECOMMENDATIONS FOR FUTURE WORK .............................................................................................................
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