1
vote
3answers
94 views

Do atoms of a surface excite to reflect the light?

How do surfaces reflect certain colours and absorb the others?
2
votes
2answers
73 views

Photon emission and absorption by atomic electrons

Assume a photon is produced by an atomic electron making a transition down from a certain energy level to another. Can that photon only be absorbed by another atomic electron making exactly the ...
2
votes
3answers
100 views

Atomic Physics: stimulated emission

I'm studying a chapter about atomic physics right now but there's thing I just don't seem to understand. When stimulated emission occurs, there's an incoming photon which stimulates the atom to go an ...
2
votes
0answers
61 views

Laser Transverse/Longitudnal Modes

When we say Laser transverse modes. Is that mean what we will get at the output spot of laser beam ? secondly In practice , what TEM01 or TEMnm means ?
0
votes
1answer
183 views

Thermionic emission and delayed emission

I want to understand the concepts behind the thermionic emission. In thermionic emission, the energy randomization occurs and the energy may be split to electronic or roto-vibrational states. If this ...
28
votes
5answers
2k views

If photon energies are continuous and atomic energy levels are discrete, how can atoms absorb photons?

If photon energies are continuous and atomic energy levels are discrete, how can atoms absorb photons? The probability of a photon having just the right amount of energy for an atomic transition is ...
3
votes
1answer
94 views

Why, in EXAFS spectrum, does the absorption coefficient monotonically decrease with increasing photon energy?

In atomic physics, it is common knowledge that following the absorption edge, where the photon energy equals the binding energy of a core electron, a monotonic decrease in the absorption coefficient ...
8
votes
1answer
887 views

Why are noble gases used for lights?

I know that neon is used in advert signs due to its inertness. However, I am not entirely sure how the inertness is exploited. I think it is because Ne being inert means that after electricity frees ...