Fig. 7: Energy level structure variation of the CDs by the protonation treatment. | Nature Communications

Fig. 7: Energy level structure variation of the CDs by the protonation treatment.

From: Photoluminescence mechanism of carbon dots: triggering high-color-purity red fluorescence emission through edge amino protonation

Fig. 7: Energy level structure variation of the CDs by the protonation treatment.

a−c full-scale ultraviolet photoelectron spectroscopy (UPS), near Fermi energy (low binding energy) and secondary electron cut-off (high binding energy) regions of CDs before the protonation; d−f UPS, near Fermi energy and secondary electron cut-off regions of CDs after the protonation. g UV−Vis spectra, h one-photon fluorescence spectra; i two-photon fluorescence spectra of CDs before and after the protonation. (P-CDs: CDs after the protonation treatment).

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