Nuclear-spin relaxation rates resulting from shape fluctuations of unilamellar quasispherical vesicles are calculated. We show that in the kHz range these fluctuations yield—in contrast to previous conclusions on planar membranes – a relaxation rate proportional to the inverse Larmor frequency and provide direct information on the bending rigidity of membranes.

• Received 31 March 2001

DOI:https://doi.org/10.1103/PhysRevE.64.022902