Is the Energy Band of Wood vs Crystals similar?

[rodsika]

　

Is the Energy Band of Wood vs Crystals similar?

　

As I understand it. In crystals the interaction of the atoms are more intimate.. meaning all the atoms in the crystals can influence one another which produced solid energy band. While in wood, the distance are further and hence the interaction are not as intimate and the energy band is not as packed or solid. However, someone in the google newsgroup mentions the following which implies the energy band is the same. Is he correct?

He wrote:

"Even amorphous substances can have energy bands. For example, there is
not a great a change of electronic conductivity when a metal like
mercury changes from a solid to a liquid.

UYou may know that when two atoms are in proximity, they couple to split
the levels. Three or more adjacent atoms can interact to mutually split
levels. It is this splitting that is an energy band.

The reason crystal are often used as examples of splitting and band
formation is because of their regularity. This means that an electron
will not collide often with the lattice. that is, the crystal
periodicity leads to high mobility and conductivity but not to the bands
themselves. That is why small impurity and work hardening in copper can
significantly reduce the conductivity. Lattice vibrations, phonons, are
also lattice defects and reduce conductivity.

Bill "

 

[StandardAuNP]

Hmmm...Where to start?

Similar in what way?

 

[DrDu]

　

Is the Energy Band of Wood vs Crystals similar?

　

As I understand it. In crystals the interaction of the atoms are more intimate.. meaning all the atoms in the crystals can influence one another which produced solid energy band. While in wood, the distance are further and hence the interaction are not as intimate and the energy band is not as packed or solid. However, someone in the google newsgroup mentions the following which implies the energy band is the same. Is he correct?

He wrote:

"Even amorphous substances can have energy bands. For example, there is
not a great a change of electronic conductivity when a metal like
mercury changes from a solid to a liquid.

UYou may know that when two atoms are in proximity, they couple to split
the levels. Three or more adjacent atoms can interact to mutually split
levels. It is this splitting that is an energy band.

The reason crystal are often used as examples of splitting and band
formation is because of their regularity. This means that an electron
will not collide often with the lattice. that is, the crystal
periodicity leads to high mobility and conductivity but not to the bands
themselves. That is why small impurity and work hardening in copper can
significantly reduce the conductivity. Lattice vibrations, phonons, are
also lattice defects and reduce conductivity.

Bill "

I think he is correct. The main difference between the energy levels of periodic and aperiodic substances is that the former ones can be labeled by the reciprocal vector k.
In the case of aperiodic substances, this is not possible. The spectrum of the effective one-electron hamiltonian may nevertheless be very similar.

 

[asheg]

If you mean difference between periodic and aperiodic array of atoms, in periodic systems we have clean and well defined bands but in aperiodic systems we have a dirty band diagram which means many energy states in energy gap regions which number of such states depends on the number of irregularities in atomic structure. You can see band diagram of amorphous silicon as an example.
But I'm not sure that one can consider wood as amorphous crystal since (I think) it's a very porous and organic material.