Dear everyone: Ihave some questions about the interpretation of "white line", from anarticle (https://doi.org/10.1038/s41467-021-27116-8) and the figure was attached. In the article, it is said that “the sample was fully reduced to Ni (0) state at ~480 °C judging from the edge position and ‘white-line’ profiles”. First, we assumed that the metal was coordinated with the same anion. We all know that K-edge transition in 3d and 4d metalis' spin forbidden, so it may be inappropriate to conclude that the intensity of the "white line" is correlated with metals' oxidation states. But in other words, the probability for s→d transition may be proportional to thenumber of empty d orbitals, so it seems like if the the intensity of "white line" is higher, the oxidation state is higher. So, how should we correctly interpret the “white line” and edge energy from XAS spectrum of metals’ K-edge and L-edge? Thank you in advance for your time. Marco Wang
