Fig. 3: Study on the structural and optical properties of CDs before and after light irradiation.
From: Photooxidation triggered ultralong afterglow in carbon nanodots
a The optical photograph of CDs in the mixed solution of water and dichloromethane before and after light irradiation. b Transmission electron microscopy images of CDs after light irradiation (scale bars: 20 nm). c 1H NMR spectra of the CDs before and after light irradiation. d Fourier transform infrared spectrum of the CDs before and after light irradiation. e Full survey XPS spectrum of the CDs before and after light irradiation. f The high‐resolution XPS O1s spectrum of the CDs before and after light irradiation. g The fluorescence spectra of the CDs before and after light irradiation. h UV‐vis absorption spectra of the CDs before and after light irradiation. i Femtosecond transient absorption (TA) spectra of CDs at indicated delay times from 0.5 ps to 5 ns. j Kinetic traces at different probe wavelength of the CDs. k Global fitting TA results of CDs without light irradiation. l TA spectra of CDs after light irradiation at indicated delay times from 0.5 ps to 5 ns. m Kinetic traces at different probe wavelength of the CDs after light irradiation. n Global fitting TA results of CDs after light irradiation. o Schematic illustration of the change in luminescence of CDs after irradiation. Note: the condition of light irradiation is kept with 660 nm, 1.5 W cm−2, 2 min. The imaging in b derived from three independent measurements.
