Positron annihilation study of
the free volume changes in bifocal contact lenses
Chem.
Met. Alloys 4 (2011) 13-17
https://doi.org/10.30970/cma4.0137
Jacek FILIPECKI, Piotr KORZEKWA, Katarzyna FILIPECKA, Małgorzata HYLA, Dominika KORZEKWA, Edmund GOLIS, Witold KORZEKWA
Positron lifetime spectroscopy has been applied
to study free volume related properties of bifocal contact lenses. The
measurements were made on new lenses and then after one, two, and three weeks
wearing. The longest lifetime, obtained via three-component analyses of the
spectra, was associated with the pick-off annihilation of ortho-positronium trapped in the
free volume. After wearing of the lenses, changes in the ortho-positronium lifetimes and
the relative intensity of the longest component were observed. The results are
discussed on the basis of a free volume model.
Typical curve of spectrum lifetime
for the measured samples of bifocal lenses.
Keywords
Positron annihilation / Contact lenses / Positronium / Free volumes