In a control experiment, solutions of caged fluorescein were irradiated with a 365 nm LED, which led to photolysis of caged fluorescein and visible changes from transparent to yellow (Fig. , top row). An absorbance peak near 490 nm emerged and grew with increased UV irradiation, indicating increased concentrations of uncaged fluorescein (Fig. ). The absorbance spectrum was consistent with the spectrum of fluorescein, the uncaged product. Samples containing caged fluorescein and ppy2-only micelles (non-upconverting) did not change color (Fig. , middle row)