What Happens When an 11 eV Photon Collides with a Hydrogen Atom?

[gnome]

Given that, for Hydrogen, the ground state energy is -13.6 eV and the first excited state energy is -3.40 eV, and the second excited state energy is -1.51 eV I conclude that:

- if a 15 eV photon encounters a ground-state hydrogen atom, the photon can be absorbed by the hydrogen electron, freeing it from the nucleus & sending it away with kinetic energy of 1.4 eV.

- if a 10.2 eV photon encounters a ground-state hydrogen atom, it can be absorbed by the hydrogen electron, raising it to the first excited state.

- if a 8 eV photon encounters a ground-state hydrogen atom, it can either sail by (or through) unaffected at all, or it can collide elastically and be scattered but retain its initial energy (except for a tiny fraction to conserve momentum).

(Please correct me if I'm wrong about any of the above.)

But what happens if an 11 eV photon collides with such an atom? Does it
a. collide elastically just like the 8 eV photon?

or

b. give up 10.2 eV of its energy to raise the electron to the 1st excited state and continue on its way with its energy reduced to 0.8 eV?

(b) seems reasonable, but with this quantum stuff, obviously "reasonable" isn't good enough. So which is it?

 

[swansont]

- if a 8 eV photon encounters a ground-state hydrogen atom, it can either sail by (or through) unaffected at all, or it can collide elastically and be scattered but retain its initial energy (except for a tiny fraction to conserve momentum).

(Please correct me if I'm wrong about any of the above.)

But what happens if an 11 eV photon collides with such an atom? Does it
a. collide elastically just like the 8 eV photon?

or

b. give up 10.2 eV of its energy to raise the electron to the 1st excited state and continue on its way with its energy reduced to 0.8 eV?

(b) seems reasonable, but with this quantum stuff, obviously "reasonable" isn't good enough. So which is it?

(b) won't happen. The photon is either absorbed, scattered, or it doesn't interact.

 

[M98Ranger]

Based on the given information, it is most likely that the 11 eV photon will be absorbed by the hydrogen electron and raise it to the first excited state, leaving the photon with reduced energy. This is because the energy of the photon (11 eV) is closer to the energy difference between the ground state and the first excited state (-13.6 eV to -3.40 eV) than to the ground state energy (-13.6 eV). This means that the photon is more likely to be absorbed and raise the electron to the first excited state rather than just passing by unaffected.

However, it is also possible that the photon could collide elastically with the hydrogen atom and be scattered with its initial energy. This would depend on the specific conditions of the collision and is less likely to occur.

In quantum mechanics, it is not always possible to predict the exact outcome of a collision with 100% certainty. The behavior of particles at the quantum level is described by probabilities, so both scenarios (absorption and elastic scattering) are possible, but with different probabilities.