# PHOTON EMISSION DURING x RAY IONIZATION PROCES

#### marck

Dear mates:

During ionization with radiant energy there is a photon emission (see http://hyperphysics.phy-astr.gsu.edu/hbase/mod3.html). I know photon emission occurs by a decay of radiant energy from a excited state and what is confusing to me (I can't find a logical conection) is that the expulsed electron from ionization takes all the radiant energy and leaves the atom with out excited levels for energy decayment.

Marco Uscanga

#### MBW

When an atom interacts with a photon it is acually the electrons that do (almost) all the interacting.
However the electrons have very precise "resonant" frequencies such that they only interact with particular wavelength photons.
In certain circumstances, they can totally absorb the photon and enter an exited state.
At some later time they may re-emit a photon (of the same frequency) and drop back to the original non-excited state.
They can also absorb the photon, and jump up several levels to a very excited state, then emit a lower frequency photon and jump down only part way to the original state.
If the amount of energy imparted by the photon to the electron is big enough then the electron will jump up so many energy levels it will jump totally out of the atom completely, leaving the atom ioniosed.

#### marck

Ok MBW I think you are alright

As you say If the adequated quantum photon energy is given , ionization may occur.

Quantum mechanics tells you that there is also a probability that a photon is emitted as a result of this collision, which would carry off some of the momentum/energy. You don't necessarily have to have excited bound electrons in order to create a photon; so ionization process that requires collision may create photons.

Am I right?

With all the best

Marco Uscanga

#### MBW

I interpreted the Compton scattering as the photon having enough energy to ionise the atom, but still have some left over.
So the electron takes as much energy as it can from the photon, leaves the atom, and the unused energy travels on as a lower energy photon.