EPR of Marine Diesel

Marine diesel was studied by electron paramagnetic resonance (EPR) spectroscopy at X-(9 GHz) and W-bands (94 GHz). The experiments were performed at room temperature (about 300 K). X-band spectra exhibited isotropy, resolved lines and negligible noise, whereas the W-band spectra exhibited a poorer signal-to-noise ratio and anisotropy in g and in hyperfine interactions. Viscosity at room temperature (2.5 · 10⁻³ kg/m · s) and the tumbling correlation time for free radicals (about 10⁻⁷ s) justified the high mobility of free radicals in marine diesel and consequently, the septet-quartet EPR spectrum of organic radicals with parameters g = 2.0028 ± 0.0005, proton hyperfine couplings A = 6.31 ± 0.01 G (septet) and A′ = 1.80 ± 0.01 G (quartet) at X-band. The perinaphthenyl radicals are probably responsible for the septet-quartet EPR spectrum of this oil by-product. Authors' address: Eduardo Di Mauro, Laboratório de Fluorescência e Ressonancia Paramagnética Eletr?nica, Centro de Ciências Exatas, Universidade Estadual de Londrina, C.P. 6014, CEP 86051-970 Londrina, Paraná, Brasil