Orpheus n

For fs-TA spectroscopy, the fundamental output from Yb:KGW laser (1030 nm, 220 fs Gaussian fit, 100 kHz, Light Conversion Ltd) was separated into two light beams. One was introduced to NOPA (ORPHEUS-N, Light Conversion Ltd) to produce a certain wavelength for the pump beam (here we use 520 nm for the Au₂₄, 550 nm for Au₁₄Cd, and 750 nm for the Au₂₄’), the other was focused onto a YAG plate to generate white light continuum as the probe beam. A 1030-nm laser was used to generate visible and NIR probe light, therefore the scattering region between 900 and 1050 nm in the data map is removed. The experiment set-up for the probes at 500–900 nm and 1050–1300 nm were different and used different pump power and pump laser beam size. Therefore, corrections are made to the pump fluences in the reported data. The pump and probe overlapped on the sample at a small angle <10°. The transmitted probe light from sample was collected by a linear CCD array. DCM or hexane solutions of nanoclusters in 1 mm path length cuvettes were excited by the pump. Transient differential transmission signals were obtained by the equation shown below: $\frac{\mathrm{\Delta }T}{T}=\frac{T\left(\mathrm{pump}-\mathrm{on}\right)-T\left(\mathrm{pump}-\mathrm{off}\right)}{T\left(\mathrm{pump}-\mathrm{off}\right)}$

We used BST-MH, BST-NT, and BST-NS films for TA measurement. For the TA measurement (Time-Tech Spectra, TA100), the fundamental output from Yb:KGW laser (1030 nm, 100 kHz, 220 fs Gaussian fit, Light Conversion Ltd) was separated into two light beams. One beam was introduced to the optical parametric amplifier (ORPHEUS-N, Light Conversion Ltd) to produce a 460 nm pump beam, and the other was focused onto a YAG plate to produce a white light continuum probe beam. A linear array detector was used to collect the transmitted probe light from the sample.

To carry out femtosecond transient absorption spectroscopy, the fundamental output from a Yb:KGW laser (1030 nm, 220 fs Gaussian fit, 100 kHz, Light Conversion Ltd) was separated into two light beams. One was introduced into a NOPA (ORPHEUS-N, Light Conversion Ltd) to produce a specific wavelength for the pump beam (here, we used 900 nm), the other was focused onto a YAG plate to generate a white light continuum as the probe beam. The pump and probe overlapped on the sample at a small angle lesser than 10°. The probe light transmitted by the sample was collected by a linear CCD array and a spectrograph (Princeton Instruments) with a liquid-N₂-cooled CCD (PrLoN-IR) at −100 °C.