1：Experimental Design and Method Selection:

The study involved synthesizing UCNPs with different dopants (Tm3+ or Er3+ as activators, Yb3+ as sensitizer) and azobenzene surfactants (C4-Azo and NO2-Azo). The experimental design focused on using NIR light (976 nm) to excite UCNPs, which emit visible light to induce cis-trans isomerization of the surfactants. Methods included absorption spectroscopy to monitor isomerization kinetics.

2：Sample Selection and Data Sources:

Samples were prepared by dissolving surfactants and UCNPs in chloroform or water. Surfactant concentrations were set below critical micelle concentration (0.05-0.1 mM), and UCNP concentrations were 5-10 mg/ml. Data were sourced from UV-vis absorption measurements.

3：05-1 mM), and UCNP concentrations were 5-10 mg/ml. Data were sourced from UV-vis absorption measurements. List of Experimental Equipment and Materials:

3. List of Experimental Equipment and Materials: Equipment included a UV-Vis-NIR spectrometer (Cary5000, VARIAN), TEM (JEM 1011, Jeol Ltd), NIR laser (975 ± 5 nm, 6 W, SheauPac, Laser Components), UV lamp (UV Inspector 380 R, Goehler HPLC Analysetechnik), and blue LED lamp (LED Spot Luxeon Royal blue). Materials included NaYF4-based UCNPs, azobenzene surfactants, chloroform, and water.

4：Experimental Procedures and Operational Workflow:

Samples were first irradiated with UV light to convert trans to cis isomers, then exposed to NIR light (976 nm) at varying intensities. UV-vis spectra were recorded at intervals to monitor absorption changes at specific wavelengths (e.g., 376 nm for C4-Azo). Control experiments included thermal relaxation in dark, NIR irradiation without UCNPs, and UCNPs in dark.

5：Data Analysis Methods:

Data were analyzed using first-order kinetics equations (e.g., Ct(A) = C0(A) * e^{-kt}), with rate constants derived from linear fits of logarithmic absorption changes over time.