Computer enhancement of CW-EPR experimental spectra resolution as a new method in investigation of molecular dynamics in pyridinium tetrafluoroborate

Abstract

The present paper reports an application of the computer method for enhancing resolution of complex CW-EPR spectra. The computer resolution enhancement method (CREM) is based on the Fourier transform, convolution and deconvolution of functions and permits determination of the fundamental parameters of the spectra: the number of resonance lines, their positions, core width parameter, and relative ratios of intensities. Thanks to the use of a simulation procedure performed with the earlier determined parameters of the spectra, we were able to find the temperature changes of the widths of individual spectral lines. An example illustrating the advantages of the CREM is the possibility of investigation of molecular dynamics and phase transitions by the CREM-aided CW-EPR. Dynamics of the radical in a complex of pyridine with tetrafluoroboric acid is reflected in changes in the hyperfine structure, core width parameter and width of individual lines in the spectrum. These changes are detectable for the complex in both powdered and single-crystal form.