How can X-ray energy transitions be identified?

[Gevorg]

Here is what I understand so far about x-ray energy transitions within an atom: The shells are divided up from lowest to highest as K, L, M, N, O, and so on. The X-ray associated with an electron dropping to a K shell is called K radiation. If the electron drops dropped from a shell directly above K (L, for example), it is called K-alpha radiation. If it drops from 2 shells above, then it is K-beta radiation.

Here's what I still don't understand: Where do K-alpha 1 and K-alpha 2 radiation come from? Are those corresponding to electrons dropping down from different L subshells? If so, how do I know which subshell each one came from?

I also don't quite understand the selection rules at play. I know that the change in the orbital angular momentum quantum number l must be plus or minus 1. Some sources say the change in the principal quantum number n must be at least one while another source I looked at said there are no selection rules for n. My modern physics professor showed us an energy level diagram for Bismuth, in which he only applied the selection rule on l.

 

[Lord Jestocost]

Have a look at the Siegbahn notation: https://en.wikipedia.org/wiki/Siegbahn_notation