Optical oxygen sensing based on triplet-triplet decay of platinum octaethylporphyrin-polystyrene film using time-resolved spectroscopy by laser flash photolysis

Abstract

Optical oxygen sensing system based on the quenching of the photoexcited triplet state of platinum octaethylporphyrin, PtOEP in polystyrene (PS) by means of time-resolved spectroscopy using laser flash photolysis has been developed. The decays of the triplet-triplet reflectance of PtOEP in PS consisted of two components (faster and slower lifetimes) in the absence and presence of oxygen. In both of faster and slower components, the lifetime decreases with increasing oxygen concentration and a Stern-Volmer plot of PtOEP-PS film exhibits linearity. However, k(q) in faster component is larger than that of slower component, indicating that two different oxygen- accessible sites exist in PtOEP -PS film. The faster and slower components are attributed to oxygen-accessible sites on the surface and bulk of PtOEP film, respectively. The contribution of different oxygen-accessible sites in PtOEP-PS film for oxygen sensing is clarified by this technique.