Tecnai g2 f20 tmp

Laser-generated NPs were characterized using transmission electron microscopy (TEM) and UV-Vis absorption spectroscopy. High-resolution images and electron-diffraction patterns were measured with an analytical TEM “Tecnai G² F20 TMP” from FEI (Laboratory of Nano and Quantum Engineering, Leibniz University Hannover, Hannover, Germany). The UV-Vis absorption spectra were measured in quartz cuvettes using the “Shimadzu UV–1900i” double beam spectrophotometer (Institute of Quantum Optics, Leibniz University Hannover, Hannover, Germany).

TEM images were obtained using a FEI Tecnai G2 F20 TMP (Cs = 2 mm, CC = 2 mm) equipped with a 200 kV field-emission gun. The samples were purified 3–4 times via precipitation with methanol/ethanol and re-dispersion in toluene/hexane prior to TEM grid preparation. Subsequently, one drop of the purified sample was placed on a carbon coated copper TEM grid and dried under ambient conditions. The obtained TEM pictures are shown in Fig. 6c,g,k. The schematic diagrams in those figure as red and yellow represent CdSe (core) and CdS (shell/crown) respectively. The QDs have a diameter of 5.94 nm ± 0.46 nm, the QRs have diameter of 5.87 nm ± 0.59 nm with length of 33.10 nm ± 2.84 nm and the NPLs have length of 38.1 nm ± 5.2 nm with width of 13.6 nm ± 2.1 nm. The NPLs have a thickness of only 5 monolayer (≈1.5 nm).

Samples were visually assessed using a transmission electron microscope (TEM, instrument: Tecnai G2 F20 TMP from FEI, voltage: 200 kV, Frankfurt am Main, Germany) and a scanning electron microscope (SEM, instrument: Helios G4 CX from FEI, voltage: 5 kV, Frankfurt am Main, Germany). Between 50 µL and 150 µL of the suspensions were dropped onto a copper grid for TEM measurements and onto a membrane filter (Whatman^® Nuclepore™ Track–etched polycarbonate membranes with pore diameter of 0.2 µm, Dassel, Germany) and dried in atmospheric air. The membrane filters for the SEM measurements were then glued to a copper grid and sputtered with 4 nm platinum.