3 ms·
Indeed. For another example, photos like this are a classic example of how particle size can affect colour: http://education.mrsec.wisc.edu/background/quantum_
by Osmium 13y ago
Indeed. For another example, photos like this are a classic example of how particle size can affect colour:
http://education.mrsec.wisc.edu/background/quantum_dots/images/blacklight-700.jpg http://education.mrsec.wisc.edu/background/quantum_dots/imag...
(solutions of CdSe nanoparticles in order of increasing particle size)
Broadly speaking, since "colour" isn't a well defined for things like atoms, but it is for macroscopic objects, it makes sense that there's some weirdness that goes on for particles in between those two extremes.
- alokv28 13y agoThe color change of gold and CdSe particles with size are due to two different effects. CdSe is a semiconductor, and reducing the CdSe nanoparticle size increases its band gap through a process called quantum confinement. For smaller particles, it requires a photon to have higher energy (i.e. smaller wavelength) to be absorbed. Gold particles derive their color from the scattering mechanism mentioned in the parent comment.
- Osmium 13y agoCompletely agreed; I was just providing another example for how the colour of large objects does not necessarily have anything to do with the colour of small objects. Thanks for the added context :)