• Optical properties (quantum effects)

The optical properties of the nanoparticles of some metals such as gold, silver and semiconductors are produced by the interaction between their plasmon surface and the incident electromagnetic wave (natural light, laser), producing a quantum effect as a consequence of the change of the electronic structure induced by the size and shape of the nanoparticle.

The color that acquires a nanoparticle on which a white ray of light (in which all the wavelengths in the visible spectrum 400-700 nm, with a similar intensity are present) is white color; If the nanoparticle absorbs some wavelength (color), it will change the color of the nanoparticle perceived by the naked eye and the color of the transmitted light. The absorbed wavelength is that whose energy causes the plasmon on the surface of the nanoparticles to vibrate at the same wavelength as the absorbed wave. The wavelength of the electron pool of the surface (plasmon) can be varied with the size and shape of the nanoparticles (surface plasmon resonance).

The red color of the stained-glass windows of cathedrals occurs when the contained gold nanoparticles have the appropriate size and shape (10-20 nm), to absorb the photons corresponding to the wavelengths of the received light, which correspond with the colors blue and green.

Conclusions

A nanomaterial differs from a conventional polycrystalline material not only because of the size of its structures, but also in the way we can use it. The electronic, optical, magnetic, chemical, and mechanical properties are substantially affected by the scale of a material’s features.

Fundamental material properties that were long considered constants (melting temperature, electrical conductivity, ductility, etc.) are suddenly subject to manipulation. We can tailor these properties by engineering the dimensions of a material’s features. QUIERO PONER QUE LAS NANOPARTÍCULAS SE PUEDEN MANIPULAR CONOCIENDO SUS PROPIEDADES Y DISEÑAR NUEVOS MATERIALES.

if the dimensions of a material are reduced, its properties are modified and accordingly materials with properties on demand can be designed.

Control questions

1. What does Nanoscience mean?

2. Give the definition of Nanochemistry.

3. How nanomaterials can be classified?

4. Explain which are the reasons for the differences in nanomaterials properties and bulk properties.

5. Mention some characteristics of nanomaterials.