The Rising Sun Envelope Method: an automatic and accurate peak location technique for XANES measurements

TL;DR

The Rising Sun Envelope Method is an innovative algorithm that automatically identifies peaks in XANES spectra without derivative reliance, improving analysis accuracy and applicability to related spectroscopic techniques.

Contribution

It introduces the first automatic peak detection method for XANES spectra that preserves peak information without derivative-based computations.

Findings

Accurately locates peaks in XANES spectra

Works with experimental and simulated data

Applicable to EELS and Raman spectra

Abstract

The lack of theoretical understanding of X-Ray Absorption Near Edge Structure (XANES) spectroscopy makes the development of analysis tools for its study a necessity. Here, an algorithm for judicious choice of local minima and maxima points of XANES spectrum (experimental or simulated) is proposed, without any loss of information on peaks location nor on peak strength. We call it the Rising Sun Envelope Method, since it is based on successive regularizations of the spectral measurement that, according to parameter choices that are intrinsic to the measurements, keep peaks location and strength as invariants. This is the first method that finds peaks in XANES automatically, without depending on first derivative information. Nevertheless, a direct computation of Absorption-Edge is provided, where we avoid the issue inflection point computations based on the XANES second derivative, dealing instead with simpler computations of inflection points of higher quality cubic spline approximation. Besides applications of the algorithm to XANES, we illustrate further applications in Electron Energy Loss Spectroscopy (EELS) and Raman spectra.