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Theoretical and Computational Investigation of Quantum Plasmonic Properties of Nanocluster Dimers

Mahmoudi, Erfan | 2022

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 55585 (03)
  4. University: Sharif University of Technology
  5. Department: Chemistry
  6. Advisor(s): Jamshidi, Zahra
  7. Abstract:
  8. In today's era, metal nanoparticles play an important role in technologies emerging from different sciences, such as chemistry, physics, optics, material science, due to their unique characteristics. In the development of nanooptics science, it can be said that metal nanoparticles play an important role. The ability of conductive electrons collective oscillation causes surface charge density fluctuations in nanoparticles, this phenomenon is known as surface plasmons. Surface plasmons are surprisingly coupled with light and cause the significant increase in the intensity of optical fields induced in nanoparticles. Therefore, with the presence of localized surface plasmons or plasmon polariton, which increase the intensity of electromagnetic fields, the applications of nanooptics science in technology have made significant progress. Therefore, the understanding of the nature and plasmonic properties of metal nanoparticles, as well as the prediction of their behavior and performance, have been considered for a long time. At this time, most of the theoretical studies were based on classical electromagnetism, which is a suitable description of this property for nanoparticles with dimensions greater than 100 nm. Recently, with the progress of experimental methods, it is possible to synthesize smaller nanoparticles with their dimensions are less than 10 nm, in which the quantum nature of the plasmon appears, and other classical methods are not suitable for describing this property. On the other hand, when the nanoparticles are placed at a certain distance (within the limit of the quantum region), the energy and absorption intensity of the observed plasmonic property can change, and also by reducing the distance and gap between two nanoparticles to less than 1 nm, a new plasmon peak appears with energy less than the main plasmon transitions. unlike the initial plasmonic absorption, the energy of this new peak increases with the decreasing of the gap between two nanoparticles, and its intensity also increases, and it is named as the charge transfer peak.Therefore, the main focus of the current research is on the field of quantum plasmonics and analyzing its characteristics with the help of computational methods based on the time-dependent density functional theory and approximated methods based on it. In this way, we will examine the electronic transitions of gold and silver nanoparticle and silver-gold nanoparticle dimer and calculate the plasmonic property by reducing the gap distance between the two nanoparticles, and also investigate the effect of the structure and type of metals on the plasmonic property
  9. Keywords:
  10. Silver Nanoparticles ; Gold Nanoparticle ; Quantum Plasma ; Load Transform ; Tunneling ; Time Dependent Density Functional Theory

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