Orientational anisotropic studies by field rotation technique: near zero-field pulsed EPR experiments of pentacene doped in p-terphenyl |
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Authors: | Lang Jun Sloop David J Lin Tien-Sung |
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Affiliation: | Department of Chemistry, Washington University, St. Louis, MO 63130-4899, USA. |
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Abstract: | We report a new technique to map the orientational anisotropy of paramagnetic systems without physically changing the crystal orientations in near zero-field (NZF) pulsed EPR experiments. By implementing three sets of orthogonal coils around the sample, we are ble to create a magnetic vector up to 2 mT in any three-dimensional orientation in space. In NZF region, the hyperfine tensor elements are comparable to the electronic Zeeman interaction energy, thus very rich spectral patterns can be obtained by "dialing" in a magnetic field vector without moving the sample. The technique further allows us to examine the site symmetry of organic crystals and powdered solids doped with chromophores which can be photo-excited to the triplet state by laser light. The technique is exemplified in the study of pentacene in p-terphenyl crystals. |
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Keywords: | Pulsed EPR Near zero-field Field rotation technique Triplet state Organic crystals |
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