Study of Stable L-Alanine Radicals by W-Band EPR Spectroscopy

Stable L-alanine radicals, SAR1 and SAR2, induced by γ-irradiation of the L-alanine crystal have been investigated by electron paramagnetic resonance (EPR) technique at W-band (94 GHz) frequency. The study provides assignment of radical centers detected by continuous-wave EPR, saturation transfer mode and echo-detected field-swept EPR at W-band frequencies. The phase memory time, Tm, which was measured simultaneously at X-band (9.5 GHz) and W-band frequencies for different spectral components has been employed to estimate rotation correlation times of CH3 protons and an effective correlation time related to the local dynamics of the entire SAR1 center at room temperature.