Silicon carbide

Catalysis

Raman spectroscopy

Oxide

Metallurgy

Materials science

Nuclear physics

Optical fiber

Diffuse reflectance infrared fourier transform

Silicon

Polymer

Physics

Organic chemistry

Irradiation

Optics

Composite material

Analytical Chemistry (journal)

Chemistry

Fluorine

Photocatalysis

Optoelectronics

Radiation Physics and Chemistry

This paper reports an increase in the optical reflectivity of two kinds of copolymers used in contact lenses, with different proportions of silicon and fluorine derivatives, when irradiated with 4.1 MeV alpha particles from an 241Am source. The fiber-optic reflectance technique showed that the lens with a higher proportion of silicon and fluorine content and a lower proportion of methyl-methacrylate is more susceptible to alpha radiation. X-Ray photoelectron spectroscopy and Raman spectroscopy have revealed the formation of silicon oxide and carbide species as a result of chain scission and recombination in the 20 μm thick irradiated regions of lens materials. It is presumed that the high (260 eV/nm) linear energy transfer of alpha particles in polymers creates trapped gas “Bubbles”, and the observed increase in the optical reflectivity with increased irradiation time is explained on the basis of diffuse reflectance caused by the scattering of light from the hard surfaces of these “Bubbles”.

The effects of alpha irradiation on the optical reflectivity of composite polymers