Question

What percentage increase in wavelength leads to a 75% loss of photon energy in a photon–free electron collision?

Answer 1

I'm wondering if there is any intuitive way to visualize how a "free" electron absorbs a photon and emits another photon of different wavelength... I know the discrete energy levels thingy applies only to the bound electron. How to visualize of this photon absorption/emission for free electrons ?

Answer 2

When I look at a mirror, the photons from my face hit the atoms in the silver paint behind the mirror, get absorbed by the electrons, and re-emitted by the electrons. Here there is no wavelength change. This allows me to conclude that the wavelength can change in a scattering/reflection only when the photons hit the free electrons...

see any flaw in my interpretation ?

Answer 3

I'm not sure, I haven't spent too much time thinking about/studying free electrons since I have a chemistry degree. I was going to ask, why do bubbles and oil slicks look like rainbows? The light is absorbed to electrons in a surface and being re-emitted and it might appear that the wavelength has changed, but really this has to do with the light constructively and destructively interfering and cancelling out part of the light rather than actually changing the wavelength of light like you're talking about here. So that's not a counterexample. Hmmm

Answer 4

yeah thin film interference is due to the difference in distance that a light beam travels; no change in wavelength occurs here... rainbow pattern is due to the fact that white light has all the visible colors and different colored light beams bend at different angles inside the thin film and spread out

Answer 5

Oh makes me worry about how reflection works... Is there any quick proof for the following :
When a ball bounces off a flat surface, the incident angle is equal to the reflected angle
\(\theta = \theta'\)