In another set of experiments, we explored the potential impact of the cylindrical capillary holder's surface. While previous experiments utilized a non-refractive black surface for this cylinder, optimizing energy utilization could involve making this surface reflective to increase photon absorption. This enhancement would manifest in two primary ways: firstly, by amplifying the received flux, and secondly, by extending the effective path length of the previously received irradiation. The enhanced flux would arise from initially missed irradiation being reflected back towards the capillary, offering another opportunity for interaction with the absorbing medium. In contrast, the extended path length would come from transmitted irradiation -already passed through the reaction mixture -being reflected for another pass. Simulations with a reflective supporting cylinder, assuming lossless specular reflection, indeed showed an increase in total received photon fluxes for both power settings, reaching 1.0 and 2.2 μmol s -1 (equivalent to 0.33 and 0.69 W optical power received by the reaction mixture), representing a 22% boost of the photon flux due to the reflective material. When combining these fluxes with experimental data, the effective optical path length extended to approximately ~2.3 mm (see Supplementary Figure ).