Dear Crystallographers, I have had only a vague understanding of what specific things are happening with shell electrons at anomalous edges. Specifically, for example, to what energy of electron-transition does the x-ray k-edge correspond in terms of orbitals, and is that transition energy actually equal to the energy of the photon, suggesting that the photon is absorbed (or disappears?) in elevating the electron? I don't think we say it is absorbed, so how does the energy come back out, from the electron's falling back down, right? So then there's a new photon created, or the same one comes back out? Where was it?
Further, I also have heard that the emerging anomalous/resonance photons are of the same wavelength as the incident radiation, but usually there is something lost in transitions (even non-fluorescence ones) I thought? Has it ever been definitively shown that the anomalous photons are of the same energy as the incident radiation? In the case of L-edges, why are there three separate edges? Further, if the resonance occurs when the energies are equal, why does resonance occur at energies greater than the edge? I don't think this happens in other resonance phenomena, or does it? If projects a middle-C-tone into a piano, do all of the lower notes resonate as well, according to the Kramers-Kronig relation? I think it may actually happen in the mammalian cochlea's travelling wave, but is it completely general to resonance phenomena? Just interested, and have wondered these things for a long time in the background of my mind... Jacob Keller ******************************************* Jacob Pearson Keller, PhD Looger Lab/HHMI Janelia Research Campus 19700 Helix Dr, Ashburn, VA 20147 email: kell...@janelia.hhmi.org *******************************************
