Dear all, I have two questions for you: 1: As in known, in the case for transition and rare earth elements, different valences lead to totally different properties. It is said that XRF can only detect the concentration of a certain element, but can not distinguish the valences of this element. Is there any one who can tell me why? Because the wavelength of the fluorescence emission depends on the difference between the core and outer energy state and in different combined state i.e. different valences of the element, this difference between the core and outer energy state should also be different. Is that because the resolution of detector can not tell this slim difference? 2: In the case of laser-induced breakdown spectroscopy, the electrons are excited to quasi-free electrons due to the ionization during that breakdown process, can this state of electrons be described as sth. similar to Bosse-Einstein state as for photons? The excited electrons will come back to the valence state afterwards, this valence state should be different in different combined state? If yes, then the wavelength of emission should also be different, and if this difference detectable using high resolution spectrograph? Thanks so much!