I'm learning about atomic energy levels and atomic spectra at the moment but there is something I don't quite understand.

 

When a sample of gas at low pressure was bombarded:

(1)-by a beam of electrons, what would be the possible energies of the electrons after passing through the gas?

(2)-by a beam of electrons, what photon energies would be observed coming from the gas?

(3)-by a beam of photons of known energy, what would be the possible energies of photons coming from the gas?

 

I got a lot of questions of these 3 types but the problem is I don't quite understand what the difference is between passing a beam of electrons and a beam of photons. Can someone explain it to me with examples.

 

When they ask for what the photon energies coming from the gas are, does that mean they want the value of the amount of energy emitted by making an electron drop down one (or more) energy level/s?

 

Can someone explain the difference between the 3 types of questions I have listed with examples plz?

What are the possible interactions an electron or photon can undergo?

depending upon the the energy the electron stream was at and the gas used, the ionisation of the gas could be anything from 0 to 7`th ionisation states as an example.

 

each gas requires different energy levels for excitation to allow photon emmision.

 

without specifics, a conclusive answer is impossible