Optical oxygen pressure sensing based on triplet-triplet quenching of fullerene-polystyrene film using laser flash photolysis: Soccerballene C₆₀ versus rugbyballene C₇₀

An optical oxygen-sensing system based on the triplet lifetimes of fullerenes C₆₀ and C₇₀ in polystyrene (PS) under different oxygen pressures was developed using laser flash photolysis. The lifetime of the photoexcited triplet state of fullerene-PS film decreases with increasing oxygen pressure. The photoexcited triplet state of fullerene-PS film was effectively quenched by oxygen. The quenching rate constant of the photoexcited triplet state of C₆₀ and C₇₀ in PS film by oxygen, k(q), were estimated to be 6.6x 10² and 1.4 x 10³ Torr^-1 s^-1, respectively (1 Torr = 133.322 Pa). The linearity of a Stern-Volmer plot of C₆₀-PS film (r² = 0.999) is superior to that of C₇₀-PS film (r² = 0.992). These results show that C₆₀- and C₇₀-PS films are highly sensitive for oxygen in the total oxygen pressure region and in the low oxygen pressure region, respectively.