研究目的
To study the photophysics of water-soluble carbon dots (CDs) dispersed in different pH solutions using time-resolved photoluminescence emission, focusing on the ? 100 ps time-scale dynamics and the impact of pH on emission characteristics.
研究成果
The study reveals that the emission characteristics of CDs are deeply influenced by the pH of the solution, with deprotonation of surface acidic groups leading to significant changes in emission properties. The CDs exhibit potential as optical pH sensors, especially at pH ranges where deprotonation of -COOH and phenolic -OH groups occurs. The findings provide insights into the photophysics of CDs and their application in sensing technologies.
研究不足
The study focuses on the ? 100 ps time-scale dynamics, which may not capture all aspects of the photophysical processes in CDs. The interpretation of τi values from multi-exponential fits is limited by the lack of supporting evidence for their physical significance.
1：Experimental Design and Method Selection:
The study employed time-resolved photoluminescence emission spectroscopy to investigate the photophysics of CDs at different pH levels. The method of Time-Resolved Area Normalized Emission Spectra (TRANES) was used to distinguish between different emitting species in the excited state.
2：Sample Selection and Data Sources:
CDs were synthesized using L-ascorbic acid (AA) and Cu(OAc)2.H2O as precursors. A series of solutions with varying pH levels were prepared from the as-prepared CD solution.
3：H2O as precursors. A series of solutions with varying pH levels were prepared from the as-prepared CD solution.
List of Experimental Equipment and Materials:
3. List of Experimental Equipment and Materials: Equipment included a HITACHI UV spectrophotometer (U-3501), Perkin Elmer (LS 55) spectrofluorimeter, a time correlated single photon counting (TCSPC) system with a picosecond diode laser, and a Transmission Electron Microscopy (TEM) instrument (JEOL JEM 2100 HR).
4：Experimental Procedures and Operational Workflow:
Photoluminescence spectra were recorded at various excitation wavelengths. Time-profiles of emission were recorded using TCSPC at specific excitation wavelengths. TRANES curves were constructed to analyze the emission characteristics.
5：Data Analysis Methods:
The time-profile curves were fitted using multi-exponential decay functions to analyze the emission dynamics.
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