| UV–Vis–NIR absorption spectroscopy, cleaned QDs dissolved in spectroscopic-grade hexane, Perkin Elmer spectrometer, 1 nm step size, 10 mm path-length quartz cuvette, prominent broad optical-resonance band | 500 nm |
|---|---|
| Time-resolved surface-enhanced Raman spectral monitoring of adsorbed BPE under modest laser illumination | No discernible fluctuations in peak positions; the chemisorption state remained stable |
| Pristine-substrate Raman and photoluminescence baseline, 800–1800 cm⁻¹ | No background Raman or photoluminescence signals |
| Transmission electron microscopy, JEM 1011 from JEOL, Japan, 100 kV accelerating voltage, and dynamic light scattering, Malvern Instruments Ltd. Zetasizer, as-synthesized nanocrystals | Faceted nanocrystals; average particle size 10 nm |
| Powder X-ray diffraction, PANalytical Empyrean, Bragg–Brentano geometry, Cu Kα radiation (λ = 1.5419 Å), programmable divergence and anti-scatter slit, large Ni-beta filter, PIXcel1D detector in continuous mode with 3.0061° active length, 2θ = 10–80°, step size 0.0131°, 40 kV, 40 mA, sample rotation time 1 s | Peak positions matched the tetragonal chalcopyrite phase of CuFeS₂, indicating high crystallinity and phase purity |
| Energy-dispersive X-ray spectroscopy, JEOL 2200FS, 200 kV | Cu, Fe, and S were present in appropriate ratios, consistent with the expected CuFeS₂ composition; no peaks from oxidized phases or impurities were detected; the Ni peak originated from the TEM grid |
| Raman spectroscopy, bare CuFeS₂ nanocrystals dried on Si | Chalcopyrite lattice vibrations at 250–350 cm⁻¹; no impurity of different phases or defects was observed in the spectra |
Shashank K. Gahlaut, Biswajit Bhattacharyya, Guilherme Carraro Carella, Gino Wegner, Evgenii Titov, Felix Stete, Laura Baier, Radwan M. Sarhan, Peter Saalfrank, Andreas Taubert, Matias Bargheer, Kurt Busch, Ilko Bald. “Light-driven electron-transfer catalysis on earth-abundant CuFeS₂ nanocrystals probed by operando SERS.” ChemRxiv (). https://doi.org/10.26434/chemrxiv.15007925/v2
Excitation-dependent SERS signal-performance comparisons were not retained. The paper describes additional Supporting Information, but no separate Supporting Information file was available on the ChemRxiv article page when acquired
| Electronic absorption in the visible region | None |
|---|---|
| Surface-enhanced Raman spectroscopy of 1 µM BPE adsorbed on CuFeS₂ nanocrystals, 488 nm excitation | 1600 and 1640 cm⁻¹ |
| Characteristic surface-enhanced Raman bands: NTP (e.g.); DMAB | NTP NO₂ stretching vibration at 1335 cm⁻¹; under near resonant excitation conditions, distinct DMAB azobenzene stretching vibrations appeared near 1140, 1390, and 1442 cm⁻¹, including the a₍g₎ modes of DMAB at 1442 cm⁻¹ |
|---|---|
| Time-series surface-enhanced Raman spectroscopy, 457 nm excitation | The DMAB bands appeared in addition to the NTP signals and progressively intensified with illumination time; temporal evolution of normalized SERS intensities for the reactant band at 1335 cm⁻¹ and product band at 1442 cm⁻¹ was extracted from the spectra |
| High laser power densities | Carbonization and a distinct “burning” of the sample were observed; the characteristic DMAB vibrational modes decreased while two broad Raman bands centered at approximately 1350 and 1580 cm⁻¹ emerged, assigned to the D (disorder) and G (graphitic) bands of amorphous carbon, respectively |