Revisiting the Question of Information Content of EXAFS Spectra through a Bayesian Approach

Over the last several decades the Shannon-Nyquist criterion has been widely used as a measure of the maximum information content in EXAFS spectra and provided an upper limit on the number of parameters used in fitting data. However, the criterion implicitly assumes independent parameters which is never the case in EXAFS analysis. Here we introduce a new criterion to measure the information content in EXAFS based on Bayesian approach that lifts the above condition. We test the new criterion by fitting the EXAFS spectrum of liquid gallium and demonstrate that not only it does constitute a superior measure of the data information content, but can also provide guidance in data analysis to differentiate between various fitting strategies.