Reflection of different metals

1. sophieyeomans

1
1. The problem statement, all variables and given/known data
Having done an experiment measuring the intensity of light reflected from copper, lead, zinc and iron, i found that copper reflected the most light, then iron, then zinc, then lead.

Now i have to explain it and I dont really know how to !

3. The attempt at a solution

I was thinking perhaps something to do with the fact that each of the metal atoms has different structures, and so different allowed quantum energies with which to absorb and emit light, so thats why they are all different?

But then I'm measuring light intensity, and doesn't intensity relate to the number of photons emitted, not the energy of each photon??

I'm really confused!

And what about the fact that they are not single atoms, but a lattice, with freely moving electrons?

2. interested_learner

214
Look at the different metals. Is the light being scattered from their surfaces different colors? What does this say about the frequencies of scattering? Quantum states?

Now look at the standard dispersion equation which is:

$$n = 1+\frac {q_e^2}{2m \epsilon }\sum_k \frac {N_k} {\omega_k^2 - \omega^2 + i\gama_k \omega}$$

Now the what happens when the $$\omega_k$$ of the metal approaches the $$\omega$$ of the source light? Under what conditions does the absorption peaks? how about scattering peaks?

What affect does the $$i\gama_k \omega}$$ electron damping factor have on the above questions? Why do you think that when the surface oxidizes (which sends the $$\omega_k$$ all over the place) do we get a dull surface?

Also think about interference. How does that affect the scattering? Why do we get a lot of scattering at certain angles and not at others?

Last edited: Mar 24, 2007