The shapes of NMR absorption lines, free induction decays, and Jeener echoes in systems such as lyotropic liquid crystals have been investigated theoretically and experimentally. For a system having an axis of symmetry for the molecular motion which makes an angle Vthgr; with the external magnetic field, the secular part of the dipolar Hamiltonian lang;Hdrang; (Vthgr;) is proportional to (1/2)(3thinsp;cos2Vthgr;minus;1). This leads to the characteristic logarithmic absorption line shape for nonoriented systems. The experimental consequences are illustrated with measurements on nonoriented samples of potassium palmitatendash;water in the lamellar liquid crystal phase.
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