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We report pulsed Electron-Nuclear-DOuble-Resonance (ENDOR) experiments at 95 GHz and 1.2 K of single crystals of the blue-copper protein azurin and its fully 15N-enriched analogue. The nitrogen ENDOR spectra and their variation with the orientation of the magnetic field with respect to the crystals are described, and it is shown that contributions of five distant nitrogens may be distinguished. For the remote nitrogens of the copper ligands histidines-46 and -117 complete hyperfine and quadrupole tensors are presented and discussed in relation to the structure of the copper site and the extension of the wave function of the unpaired electron. Besides these nuclei three backbone nitrogens show up in the ENDOR spectra, and their hyperfine tensors are reported. One of the backbone nitrogens concerns that of cysteine-112; the others are tentatively assigned to histidine-46 and glycine-45. The wave function of the unpaired electron of oxidized azurin is found to be smeared out over both the copper ligands and parts of the protein backbone.

The W-band continuous-wave electron paramagnetic resonance (EPR) analysis of chemically induced polarons in drop-cast and spin-coated polyphenylenevinylene-type and polythiophene-type polymer films reveals rhombic g tensors in both cases. The dependence of the W-band EPR signals on the orientation of the spin-coated films with respect to the magnetic field indicates a high degree of backbone alignment with the substrate and allows a partial assignment of the g tensor orientation. The derived molecular orientations of the polymer chains in the spin-coated films show clear differences between the two types of polymers. The proton hyperfine interactions obtained from X-band HYSCORE (hyperfine sublevel correlation) and Q- and W-band pulsed ENDOR (electron-nuclear double resonance) experiments are interpreted in terms of earlier theoretical studies on the extension of the polarons.