The surface and composition study of the synthesized nanocomposites were carried using different spectroscopic methods. The XPS analysis with a binding energy of 284.8 eV for the C 1s level as an internal reference was performed with a Kratos Axis Ultra DLD spectrometer employing an Al Kα monochromatized radiation as an X-ray source. The microstructural morphologies of the samples were examined by HRTEM (JEOL JEM2100). Raman scattering spectra were collected using a Renishaw confocal Raman spectroscope (Renishaw inVia, Gloucestershire GL12 7DW, United Kingdom) with a laser operating at 514.5 nm wavelength and 10 mW power output. The studied area on the sample surface was 2 μm in diameter.
To study the optical properties, the N-CDs and CdTe/N-CDs on the Cu substrate were immersed in ethanol and sonicated for 20 min. The UV-vis absorption spectrum of the resulting solution was recorded with a Shimadzu 3600 UV-vis near-infrared spectrophotometer. The fluorescence emission was measured by a Shimadzu RF-6000 spectrofluorimeter, and the lifetime spectrum was obtained in a FM-4P-TCSPC spectrofluorimeter. The excitation wavelength was 370 nm and the emission wavelength was 428 nm. All measurements were performed at room temperature.
To study the optical properties, the N-CDs and CdTe/N-CDs on the Cu substrate were immersed in ethanol and sonicated for 20 min. The UV-vis absorption spectrum of the resulting solution was recorded with a Shimadzu 3600 UV-vis near-infrared spectrophotometer. The fluorescence emission was measured by a Shimadzu RF-6000 spectrofluorimeter, and the lifetime spectrum was obtained in a FM-4P-TCSPC spectrofluorimeter. The excitation wavelength was 370 nm and the emission wavelength was 428 nm. All measurements were performed at room temperature.