Hello I measured temperature-dependent EXAFS at Pt L3 edge with Pt nanoparticles in room and high temperature(400 C). I have some questions about thermal vibration in EXAFS fit. I read that third and fourth culmulants related with phase and amplitude in anharmonic term, respectively. especially, I concerned third culmulant to relate with phase. As you know, the phase also relates with bonding length. So that, the bonding length between Pt-Pt pair considerably correlated with third culmulant. So I can't decide exact bonding length and third culmulant because their correlation. I think that the relation of both bonding length and third culmulant is similar to that of number and debye-waller factor. Is it right to find bonding length and third culmulant like finding number and debye-waller factor using k-weight?