Photoluminescence of carbon dots from mesoporous silica
| Autor: | A. N. Starukhin, Valery G. Golubev, D. A. Kurdyukov, B. S. Razbirin, E. Yu. Stovpiaga, D. A. Eurov, D. K. Nelson |
|---|---|
| Rok vydání: | 2016 |
| Předmět: |
Photoluminescence
Materials science Analytical chemistry chemistry.chemical_element 02 engineering and technology 010402 general chemistry 01 natural sciences Molecular physics Inorganic Chemistry Electrical and Electronic Engineering Physical and Theoretical Chemistry Spectroscopy Organic Chemistry Mesoporous silica 021001 nanoscience & nanotechnology Fluorescence Atomic and Molecular Physics and Optics 0104 chemical sciences Electronic Optical and Magnetic Materials Dipole chemistry 0210 nano-technology Phosphorescence Luminescence Carbon Excitation |
| Zdroj: | Optical Materials. 59:28-33 |
| ISSN: | 0925-3467 |
| Popis: | Photophysical properties of carbon dots were investigated under various excitation conditions and over a wide temperature region – from room to liquid helium temperatures. The carbon dots (CDs) were synthesized using mesoporous silica particles as a reactor and (3-aminopropyl)triethoxysilane (APTES) as a precursor. The photoluminescence spectra of CDs exhibit a strong dependence on the excitation wavelength and demonstrate a significant inhomogeneous broadening. Lowering sample temperature reveals the doublet structure of the spectra, which is associated with the vibronic structure of radiative transitions. The vibration energy ∼1200 cm −1 is close to the energy of C O stretching vibration. Long-lived phosphorescence of carbon dots with its decay time ∼0.2 s at T = 80 K was observed. The fluorescence and phosphorescence spectra are shown to be spectrally separated. The long-lived component of the emission was ascribed to optically forbidden triplet-singlet transitions. The value of the singlet-triplet splitting was found to be about 0.3 eV. Photo-induced polarization of the luminescence of carbon dots was revealed. The degree of the linear polarization is dependent on the wavelengths of both excitation and emitted light. The effect indicates a hidden anisotropy of optical dipole transitions in the dots and demonstrates the loss of the dipole orientation during the electron energy relaxation. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|
Full Text from ScienceDirect