A strategy for substantially reducing powder-pattern linewidths in ESEEM spectra of spin 1 2 nuclei is demonstrated in the 4 to 12 GHz ESEEM spectra of the radical anion of para-nitrobenzo-15N-nitrile. Line-broadening associated with axial hyperfine interactions can be eliminated in one branch of the ESEEM powder-pattern by optimal selection of external field strength. This line-narrowing strategy extends the applicability of ESEEM spectroscopy to systems with arbitrarily large dipolar couplings. 15N hyperfine coupling constants of the studied radical are evaluated from the multifrequency ESEEM spectra. The impact of rhombic hyperfine couplings on the spectra is discussed and explicitly considered in the quantitative analysis of the experimental results.
ASJC Scopus subject areas
- Physics and Astronomy(all)
- Physical and Theoretical Chemistry