Emission spectroscopy in air of L12 liposomes in PBS supplemented with l-Asc or GSH. (a) Absorption (solid) and emission spectra (dotted: t = 0; dashed: t = 5 min) of L12 liposomes in PBS supplemented with 5 mM l-Asc. Inset shows the upconversion intensity (IUC at 474 nm) for the first 5 min of irradiation with 3 s intervals; (b) Time trace of the upconversion intensity (IUC at 474 nm, blue), phosphorescence intensity (Ip at 800 nm, red), and dissolved oxygen concentration (black) during red light irradiation of L12 liposomes in PBS supplemented with 5 mM l-Asc. The laser was turned on after 74 min in the dark, as indicated by the arrow. Exp. conditions: [DLPC] = 1 mM, [1] = 0.5 µM, [2] = 5 µM, 2.25 mL sample, T = 20 °C, 10 mW 630 nm laser excitation (80 mW/cm2) with approximately 8% of the volume simultaneously irradiated, pH 7.0–7.6.