Journal
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
Volume 18, Issue 5, Pages 3838-3845Publisher
ROYAL SOC CHEMISTRY
DOI: 10.1039/c5cp07558k
Keywords
-
Funding
- Research Fund for the National Basic Research Program of China (973 Program) [2013CB922200]
- National Natural Science Foundation of China [11474129, 11574115]
- China Postdoctoral Science Foundation [2014M551169]
- Graduate Innovation Fund of Jilin University [2015091]
Ask authors/readers for more resources
Ultrafast carrier relaxation dynamics in fluorescent carbon nanodots is investigated by femtosecond transient absorption spectra at different pH environments so as to understand the mechanism of fluorescence for the first time. Utilizing multi-wavelength global analysis to fit the measured signal via a sequential model, four different relaxation channels are found, which are attributed to electron-electron scattering and surface state trapping, optical phonon scattering, acoustic phonon scattering and electron-hole recombination respectively. The results reveal that the surface states are mainly composed of different oxygen-containing functional groups (epoxy, carbonyl and carboxyl) and carbon atoms on the edge of the carbon backbone and can effectively trap a large number of photo-excited electrons. The deprotonation of carboxyl groups at high pH will change the distribution of pi electron cloud density between the carbon backbone and surface states and consequently, compared with the excited electrons in the acidic and neutral environments, those in the alkaline environment can be more easily trapped by the surface within 1 ps, thereby giving rise to stronger fluorescence emission.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available