Figure 3. a) The UV/Vis absorbance (black line), FL emission (red line) andexcitation (blue line) spectra of the URTP CDs in water (inset: water dispersionunder daylight and UV lamp (365 nm)). b) phosphorescence emission spectraat different excitation wavelengths and excitation spectrum at emission of535 nm of the URTP CDs powder under ambient conditions. c) Phosphorescence decay spectrum and fitting curve (red line) of the URTP CDs powderunder ambient conditions (excitation and emission wavelengths were set at340 nm and 535 nm, respectively). d) Proposed FL and phosphorescenceemission processes of the URTP CDs powder and aqueous solution (theabsorption processes were omitted for clarity).