Abstract
The structural analysis of crown ether was carried out with positron annihilation lifetime spectroscopy. The lifetime of o-Ps was increased with the number of ether group from 0.91 ns to 1.51 ns. The radius of nanoscale open space of crown ether calculated by using Tao-Eldrup equation showed good agreement with the cavity size of crown ether measured with other analytical method such as XRD etc, and this suggested that the annihilation site of o-Ps was in the cavity of crown ether. In comparison between B18C6 and DB18C6, it was found that the lifetime of o-Ps was changed from ca. 1.1 ns to ca. 1.3 ns with the number of benzene ring and the relative intensity of pick-off annihilation of o-Ps was influenced by the number of benzene ring. The change of the lifetime of o-Ps would be due to the influence of chemical modification on the shape of the crown ether ring, and the difference of the relative intensity between them seems to be caused by the inhibition of positronium generation by benzene in molecule.
