AcknowledgementsFirst and foremost, all the praises and thanks are due to ALLAH for endowing me withhealth and guiding me to the right path that enable me to complete my thesis in despite of allchallenges and dif?culties.Acknowledgement is due to the King Saud University represented by the deanship ofgraduate studies and the department of physics and astronomy that provided me with all thefacilities throughout of my academic career and supported me to carry out this research work.I wish to express my deep gratitude for my supervisor, Dr. Andreas Lyras, for inspiration,guidance, freedom and con?dence given for me to suggest the topic of my project and itsideas. In addition, my sincere gratitude is also due to my co-supervisor Prof.
MohammadAlSalhi the head of physics and astronomy department for continuous encouragements,logistical help and trust he had shown in me which excited me to do my best.I hardly express my gratitude for Prof. Zain Yamani, the director of the King FahdUniversity of Petroleum and Minerals center of excellence in Nanotechnology, and thevice president of saudi physical society for honest feedback, constructive comments, usefuldiscussions and the time giving for me through his review of my drafts.Finally, my deepest gratitude and warmest appreciation are due to my family for love,care, encouragements and prayers throughout my academic career.
