The simplex algorithm is a natural choice in applications requiring the analysis of spectra by curve fitting. The kinds of spectra which have been analyzed in this way include: positron lifetime spectra, NMR spectra for which overlap of lines made the use of the computer program LAOCN3 unsuitable, energy dispersion spectra, Mössbauer spectra, spectra recorded with the use of heterodyne detection, and spectra consisting of multiple overlapping Gaussian components. Beckwith and Brumby used the simplex algorithm to simulate ESR spectra with the aim of determining the spectral parameters precisely. They applied their method to the analysis of ESR spectra of free radicals in solution, but stressed the generality of the method. Fajer <i>et al.</i> similarly used the simplex algorithm for the fitting of ESR spectra.
Steven Brumby, "ESR Spectrum Simulation: The Simplex Algorithm with Quadratic Convergence and Error Estimation," Appl. Spectrosc. 46, 176-178 (1992)