1 research outputs found
Unravelling the Multiple Emissive States in Citric-Acid-Derived Carbon Dots
Steady-state and time-resolved fluorescence
spectroscopy techniques
were used to probe multifluorescence resulting from citric-acid-derived
carbon dots (C-dots). Commonly, both carboxyl-/amine-functionalized
C-dots exhibit three distinct emissive states corresponding to the
carbon-core and surface domain. The shorter-wavelength fluorescence
(below 400 nm) originates from the carbon-core absorption band at
∼290 nm, whereas the fluorescence (above 400 nm) is caused
by two surface states at ∼350 and 385 nm. In addition to three
emissive states, a molecular state was also found in amine-functionalized
C-dots. Time-resolved emission spectra (TRES) and time-resolved area
normalized emission spectra (TRANES) were analyzed to confirm the
origin of excitation wavelength-dependent fluorescence of C-dots.
The surface functional groups on the C-dots are capable of regulating
the electron transfer to affect the multifluorescence behavior. The
electron transfer takes place from the carbon-core to surface domain
by the presence of −COOH on the surface and <i>vice versa</i> for the case of −NH<sub>2</sub> present on the surface. To
the best of our knowledge, this is the first report that the multiemissive
states are probed in C-dots systems using TRES and TRANES analyses,
and related fluorescence mechanisms are verified clearly