I was looking at the excitation spectrum of a few elements in the first page of this document: http://www.amptek.com/pdf/Choosing%20the%20anode%20material%20in%20an%20x-ray%20tube.pdf In particular I was looking at Rhodium. I was wondering where does the continuum for Rhodium above k-alpha and k-beta peaks come from(k-alpha for Rh is 20.2kev and k-beta is 22.7kev)?
Is the reason that the two peaks for k-alpha and k-beta highest because the probability of an electron from the L-shell and M-shell filling the ejected k-shell electron is higher? If so, does that mean the continuum past the two peaks is the result of electrons from the outer shells(N,O,etc...) filling the k-shell, but it's just a lower probability of that happening hence there are no peaks, just a continuum? Or is the continuum a result of electrons from N-shell and O-shell filling ejected L-shell electrons? or a combination?