Laser-Induced Deposition of Plasmonic Ag and Pt Nanoparticles, and Periodic Arrays

Surfaces functionalized with metal nanoparticles (NPs) are of great interest due to their wide potential applications in sensing, biomedicine, nanophotonics, etc. However, the precisely controllable decoration with plasmonic nanoparticles requires sophisticated techniques that are often multistep and complex. Here, we present a laser-induced deposition (LID) approach allowing for single-step surface decoration with NPs of controllable composition, morphology, and spatial distribution. The formation of Ag, Pt, and mixed Ag-Pt nanoparticles on a substrate surface was successfully demonstrated as a result of the LID process from commercially available precursors. The deposited nanoparticles were characterized with SEM, TEM, EDX, X-ray diffraction, and UV-VIS absorption spectroscopy, which confirmed the formation of crystalline nanoparticles of Pt (3–5 nm) and Ag (ca. 100 nm) with plasmonic properties. The advantageous features of the LID process allow us to demonstrate the spatially selective deposition of plasmonic NPs in a laser interference pattern, and thereby, the formation of periodic arrays of Ag NPs forming diffraction gratin

ZnTe Crystal Multimode Cryogenic Thermometry Using Raman and Luminescence Spectroscopy

In this study, ZnTe crystal was applied to provide precise thermal sensing for cryogenic temperatures. Multiple techniques, namely Raman and photoluminescence spectroscopies, were used to broaden the operating temperature range and improve the reliability of the proposed thermometers. Raman-based temperature sensing could be applied in the range of 20–100 K, while luminescence-based thermometry could be utilized in a narrower range of 20–70 K. However, the latter strategy provides better relative thermal sensitivity and temperature resolution. The best thermal performances based on a single temperature-dependent parameter attain Sr = 3.82% K−1 and ΔT = 0.12 K at T = 50 K. The synergy between multiple linear regression and multiparametric thermal sensing demonstrated for Raman-based thermometry results in a ten-fold improvement of Sr and a two-fold enhancement of ΔT. All studies performed testify that the ZnTe crystal is a promising multimode contactless optical sensor for cryogenic thermometry

Stoichiometry Control in Dual-Band Emitting Yb³⁺-Doped CsPbCl_<i>x</i>Br_3–<i>x</i> Perovskite Nanocrystals

Perovskite nanocrystals (NCs) are currently one of the most efficient optical materials in the visible spectral range. Much attention is paid to extending their efficiency to the near-infrared (NIR) spectral region, which will significantly benefit their applications in optoelectronics, photonics, and biomedicine. To further promote this effort, we developed a novel synthetic approach to dual-band emitting Yb3+-doped perovskite NCs, whose stoichiometry and hence the position of the visible photoluminescence can be tuned independently of the Yb3+-precursor. The intensity of the NIR emission from Yb3+ ions shows a notable nonlinear dependence on the excitation power. To describe the corresponding redistribution of the photoluminescence intensities between the emissive channels, we developed a theoretical description of the relaxation dynamics in the doped NCs, including both the energy transfer and quantum cutting processes. Finally, we showed that the dual-band photoluminescence in the doped NCs can be excited via two-photon absorption. Our findings thus pave the way for new nanomaterials that can be operated entirely in the NIR spectral range