Color emulation
There are several ways to make a material have color.
Contents
Local origins of color
The electons in molecules are layered over one another since they are fermions and thus obey paulis exclusion principle. Light can only be absorbed when at least the energy to the next higher allowed energy level is reached (and some further restrictions are obeyed). In simple molecules like dinitrogen (air) very high photo energies are needed to excite an electron (hard UV?). The problem is that the excited electron was responsible for the bond between the two atoms so the molecule falls apart.
Creating chains of double-bonded carbon atoms creates a big shared space for the participating electrons. Since they now have more spacial freedom according to heisenbergs uncertainty principle their impulse can be smaller. This has the nice effect that you gain some energy levels that are higher than the unexcited "sea level" of molecule orbital electrons[1] but are still low enough such that the electrons still fulfill their responsibility of holding the molecule together. (the molecules shape may change though sometimes)
Visible light with its low energy can be absorbed by lifting electrons into these intermediate energy levels. The remaining light appears in a certain color.
[note 1] also known as HOMO - for highest occupied molecular orbital) meaning that
At the short blue wavelengths such chains become so short that the discreteness of the number of bond becomes problematic.
metal complexes can do that
Chain like molecules may be hard to mechanosythesize (or not).
- Pigments: [1]
- Color centers: [3]
Bigger scale origins of color
Color form wave interference
- like the ones butterflies use or simpler ones like ...
- Wikipedia: Structural coloration & Iridescsnce & Diffraction gratings
- Wikipedia: Interferometric modulator display
Color from plasmonic surface effects
[Todo: check inhowfar quantum dots are related]
