EPR investigation of atoms in chemical traps

• Published in: Carbon (New York) Vol. 38; no. 11; pp. 1635 - 1640
• Main Authors: Dinse, K.-P, Käß, H, Knapp, C, Weiden, N
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 2000; Elsevier Science
• Subjects: A. Fullerene; B. Doping; C. EPR; Color centers and other defects; Condensed matter: electronic structure, electrical, magnetic, and optical properties; D. Electronic structure; Electron paramagnetic resonance and relaxation; Electron-nuclear double resonance (endor), electron double resonance (eldor); Exact sciences and technology; Magnetic double resonances and cross effects; Magnetic resonances and relaxations in condensed matter, mössbauer effect; Physics; D. Electronic structure; B. Doping; C. EPR; A. Fullerene; Paramagnetic center; Spin relaxation; ESR; Doping; Fullerenes; Nitrogen additions; Experimental study; ENDOR
• ISSN: 0008-6223; 1873-3891
• DOI: 10.1016/S0008-6223(00)00092-0

By performing high-resolution EPR and ENDOR experiments on nitrogen atoms encapsulated in C 60, the capability of the quartet spin system to sense small local fields at the site of the atom is demonstrated. Such symmetry lowering can either be induced by chemical modification of the cage or by a phase transition in polycrystalline C 60. Additional line splittings in the EPR spectrum indicate the presence of a non-vanishing zero-field-splitting. Freezing of cage rotation can be observed via the magnetic dipole interaction with 13C nuclei of the carbon shell resulting in broadening of ENDOR transitions. Fluctuating magnetic fields originating from additional paramagnetic species in solution can also be detected by their influence on the spin relaxation times.