To measure in EtOH, we used 1,3-diphenylisobenzofuran (DPBF) as a singlet oxygen scavenger as described in with methylene blue as a standard (Φ∆=0.50 ). The initial absorbance of DPBF (at 410 nm) was matched to ~0.84, whereas the absorbance of dyes was matched to ~0.03 at 500 nm. In both experiments, single 500 nm LED was used. The results were corrected for the non-zero width of excitation spectrum.