Fig. 2: Single particle spectroscopic characterization of nanorods: comparison of directional growth of active shell and inert shell.
a Single particle upconversion emission intensity evolution with increased excitation power density from 7 × 104 to 3 × 107 W cm−2. b Power-dependent enhancement factors of total upconversion intensity, comparing directional growth of active or inert shells to the core sample CR. c Power-dependent upconversion enhancement factors for each peak, investigating the enhancement origin of AR3@OA sample. Error bars represent the SD calculated from measurements of 20 individual nanoparticles for each sample. Colors in panels (a, b) differentiate the sample groups: yellow shades correspond to AR samples, gray shades to IR samples, and light yellow to CR. In (c), colors indicate emission wavelengths: cyan for 504 nm, dark green for 541 nm, light green for 557 nm, and red for 654 nm. Source data are provided as a Source data file.
