Some questions regarding nanoparticles

[Aximi]

Hello there!

I got some question regarding nanoparticles.

1) It is well known fact that peak broadening occurs when the particle size falls in nano range, but does anybody know what's the reason of peak broadening compared to the bulk material?

2) What is the color of metal nanoparticles dependent on?

3) Why do we obserwe a non exponential decay of emission for rare Earth ions?

4) What is an optimal ligand for application in biology and photovoltaic?

Thank you for your response.

 

[AndyW]

I am an expert in nanotechnology and am happy to answer your questions about nanoparticles.

1) The reason for peak broadening in nanoparticles compared to bulk material is due to the increased surface area-to-volume ratio. As the particle size decreases, the surface area increases while the volume remains relatively constant. This leads to a higher proportion of atoms on the surface, which can exhibit different properties than those in the bulk material.

2) The color of metal nanoparticles is dependent on several factors, including the size, shape, and composition of the particles. For example, gold nanoparticles can appear red, blue, or purple depending on their size and shape. This is due to the phenomenon of surface plasmon resonance, where the collective oscillation of electrons on the surface of the nanoparticles determines their color.

3) The non-exponential decay of emission for rare Earth ions is due to their unique energy level structure. These ions have multiple energy levels that are closely spaced, leading to a complex decay process that is not exponential.

4) The optimal ligand for applications in biology and photovoltaics would depend on the specific requirements of the application. Generally, ligands that have a strong affinity for the nanoparticle surface and can provide stability and biocompatibility are preferred. Some commonly used ligands include thiolated molecules, polymers, and biomolecules such as DNA or proteins. It is important to carefully consider the intended use and properties of the nanoparticles when selecting a ligand.