First Chapter focuses on deformation mechanisms in nanocrystalline metals, specifically focusing on the role of grain boundaries and dislocations. Nanocrystalline metals are materials with extremely small grain sizes, typically in the nanometer range, which can exhibit unique mechanical propertiesSecond Chapter underscores the diverse range of applications and advantageous properties of gold nanoparticles, making them a valuable and promising material in various scientific and technological fieldsThird Chapter explores the phenomenon of Electron Magnetic Resonance (EMR) in nanoparticles and discusses its unique characteristics. EMR, also known as Electron Paramagnetic Resonance (EPR), is a spectroscopic technique that investigates the behavior of unpaired electrons in materials.