DNP and ESR at 5 T Fields
Room temperature dynamic nuclear polarization (DNP) measurements on the ID organic conductor fluoranthenyl radical cation salt (FA) are reported. Magic angle spinning (MAS) and 1h/13c cross polarization (CP) were employed to detect the enhanced 13c signals from powder samples. A enhancement factor of 8 was achieved by pulsed microwave excitation of the electronic spin system. A theoretical description of this pulsed technique has been developed and a comparison to CW method is made. ESR spectra of the P700+-donor radical of photosystem I (PS I) at room temperature demonstrate the benefits of high fields: the increased spectral resolution and measurement of small g-anisotropies.