This dataset contains transient absorption spectroscopy data on carbon nanodots. The formation of the methyl viologen radical is used as an indicator of electron transfer (a highly absorbing species at 600 nm). The performance of a variety of electron donors is assessed.

Short-time (100 fs - 2 ns) transient absorption measurements were carried out using the second harmonic of a Ti:sapphire amplifier (Spectra-Physics Solstice) as the pump beam (90 fs pulse width, 500 Hz repetition rate, 3.1 eV photon energy). The probe spectrum was generated using a home-built noncollinear optical parametric amplifier, pumped by the second harmonic of the same Ti:sapphire amplifier. A motor-driven delay stage was used to mechanically vary the pump-probe delay. Long-time (ns – ms) transient absorption measurements were carried out in two different configurations:

Configuration 1: The third harmonic of an electro-optical Q-switched laser (InnoLas picolo AOT) was used as the pump beam (< 800 ps pulse width, 500 Hz repetition rate, 3.49 eV photon energy). The probe spectrum was generated using a home-built noncollinear optical parametric amplifier, pumped by the second harmonic of the aforementioned Ti:sapphire amplifier. A delay generator was used to electronically vary the pump–probe delay.

Configuration 2: The second harmonic of a Ti:sapphire amplifier (Spectra-Physics Solstice) was used as the pump beam (90 fs pulse width, 500 Hz repetition rate, 3.1 eV photon energy). The probe spectrum was generated by a broadband supercontinuum source (Leukos Disco). A delay generator was used to vary the pump–probe delay electronically.

Data is provided as mOD against wavelength (at specific times) or mOD against time (at specific wavelengths). The file metadata.txt contains detailed information.