Fig. 2.

Representative transient absorption spectra of aminated (A) and thiolated (B) Au NP samples (expectation value 〈N〉 = 2 photons per particle), at a series of time delays after photoexcitation: 1.5–4.5 ps, with 0.6-ps intervals. The dashed red lines are the best fits to each differential spectrum (the difference between the plasmon absorbance at elevated electronic temperature and the plasmon absorbance at room temperature) with temperature-dependent Mie theory using fixed and floating parameters described in the text. From each fit, we extract the electronic temperature of the system at the corresponding time delay. SI Text contains additional TA spectra and fits.