The interaction of ozone with polyphenylsulfide thin films studied by ellipsometry and SPR

Thin films of polyphenylsulfide (PPS) have been deposited onto silicon wafers and gold-coated glass slides by the method of spin coating. Ellipsometry and surface plasmon resonance (SPR) were performed in order to determine film thickness and index of refraction. It was found that the derived film thickness depends on spin speed as omega(-s), with s varying between 0.5 and 0.6, depending on the concentration of PPS solution, which was in good agreement with hydrodynamic theory. An accurate value of films' index of refraction of n = 1.59 was determined. The index of refraction of PPS films was found to increase on exposure to 2 ppm ozone. These results can be exploited for further development of real-time detection systems for ozone at low concentration based upon more sensitive optical techniques, such as integrated optic interferometry.