The Resolution Enhancement of Electron Spin Resonance Spectra by Self-Deconvolution with a Finite Impulse Response Operator

The method of self-deconvolution is applied to the resolution enhancement of electron spin resonance spectra (ESR). The component lineshapes of ESR spectra are basically Lorentzian, but they often carry strong Gaussian perturbations. Deconvolution with a finite impulse response operator filter to enhance the resolution of Lorentzian and Gaussian ESR band envelopes is discussed and a more general function is derived for Gauss-Lorentz convolute (Voigt) lineshapes. The method is applied initially to the simulated isotropic ESR spectrum of the ethyl radical in the liquid state and to a simulated anisotropic spectrum of a crystalline powder. Application to real spectra is illustrated by the anisotropic spectrum of bis(acetylacetonato)-copper(II) [Cu(AcAc)₂] in ethanol solution at 140 K in order to resolve the hyperfine lines. The perpendicular component of this spectrum is notable for its poor resolution.