Fluorescence Turns on-off-on Sensing of Ferric Ion and L-Ascorbic Acid by Carbon Quantum Dots

Figure 3

(a) UV-vis absorbance spectrum of HP-CQDs in the solution. (b) Absorbance and emission spectrum of HP-CQDs; the excited wavelength was 350 nm. (c) Fluorescence spectrum at different excitation wavelengths. (d) Fluorescence spectra of HP-CQDs (alone), HP-CQDs: Fe³⁺, and HP-CQDs: Fe³⁺-L-ascorbic acid.

(a)

(b)

(c)

(d)