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UV luminescence characterisation of organics in Mars-analogue substrates
摘要： Detection of organic matter is one of the core objectives of future Mars exploration. The ability to probe rocks, soils, and other geological substrates for organic targets is a high priority for in situ investigation, sample caching, and sample return. UV luminescence—the emission of visible light following UV irradiation—is a tool that is beginning to be harnessed for planetary exploration. We conducted UV photoluminescence analyses of (i) Mars analogue sediments doped with polyaromatic hydrocarbons (PAHs; <15 ppm), (ii) carbonaceous CM chondrites and terrestrial kerogen (Type IV), and (iii) synthetic salt crystals doped with PAHs (2 ppm). We show that detection of PAHs is possible within synthetic and natural gypsum, and synthetic halite. These substrates show the most apparent spectral modifications, suggesting that the most transparent minerals are more conducive to UV photoluminescence detection of trapped organic matter. Iron oxide, ubiquitously present on Mars surface, hampers but does not completely quench the UV luminescence emission. Finally, the maturity of organic carbonaceous material influences the luminescence response, resulting in a reduced signal for UV excitation wavelengths down to 225 nm. This study demonstrates the utility of UV luminescence spectroscopy for the analysis of mixed organic-inorganic materials applicable to Mars exploration.
关键词： UV luminescence,Spectroscopy,Analogue,Organic,Mars
更新于2025-09-23 15:23:52
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Progress in development of a new luminescence setup at the FinEstBeAMS beamline of the MAX IV laboratory
摘要： FinEstBeAMS is a new materials science beamline at the 1.5 GeV storage ring of the MAX IV Laboratory in Lund, Sweden. It has been built based on grazing incidence monochromatization of synchrotron light, which allows to cover a remarkably wide excitation energy range from ultraviolet to soft x-rays (4.5-1450 eV). A new mobile luminescence spectroscopy end station has been commissioned with design benefitting from the advantages of a high flux elliptically polarizing undulator light source. We report on the design of the luminescence end station, its technical realization and performance achieved so far. Special attention is paid to the experimental challenges for luminescence spectroscopy under grazing incidence excitation conditions. The first luminescence results obtained demonstrate a reliable performance of the advanced setup at FinEstBeAMS.
关键词： Luminescence spectroscopy,synchrotron radiation,wide gap compounds,VUV – XUV photoexcitation
更新于2025-09-23 15:23:52
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Synthesis of Fluorescent Ag Nanoclusters for Sensing and Imaging Applications
摘要： Metal nanoparticles have attracted more and more attention in the last years due to their unique chemical and physical properties which are very different from the metal bulk material. In particular, when the size of nanoparticles decreases below two nm, nanoparticles can be described as nanoclusters (NCs), and they present peculiar optical properties. The excited electrons in addition to specific absorption bands show also a bright luminescence related to the quantum size effect which produce discrete energy levels. Optical properties (absorption and fluorescence) of these NCs are widely used in many different applications in science and engineering, such as chemical sensors, fluorescent probes for bio imaging or in environmental issues. In the present study, we report on the synthesis of silver nanoclusters (AgNCs) in aqueous phase using silver nitrate as precursor salt and L-Glutathione (GSH) as stabilizer. AgNCs were characterized using absorption and fluorescence spectroscopy, and transmission electron microscopy (TEM). The strong absorption and luminescence shown by these NCs are very promising for a possible exploitation both as label for bioimaging and for optical sensors for heavy metal ions.
关键词： luminescence,spectroscopy,GSH-Ag Nanoclusters,optical absorption
更新于2025-09-23 15:23:52
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Contribution of electron-phonon coupling to the luminescence spectra of single colloidal quantum dots
摘要： Luminescence spectroscopy experiments were realized for single colloidal quantum dots CdSe/ZnS in a broad temperature range above room temperature in a nitrogen atmosphere. Broadening and shifts of spectra due to the temperature change as well as due to spectral diffusion processes were detected and analyzed. A linear correlation between the positions of maxima and the squared linewidths of the spectra was found. This dependence was explained by a model that takes into account the slow variation of the electron-phonon coupling strength.
关键词： temperature dependence,spectral diffusion,luminescence spectroscopy,electron-phonon coupling,colloidal quantum dots
更新于2025-09-12 10:27:22
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Optical Spectroscopy Methods in the Estimation of the Thermal Stability of Bimetallic Pd–Rh/Al2O3 Three-Way Catalysts
摘要： A series of three-way catalysts containing palladium and rhodium were prepared by an incipient wetness impregnation of support with aqueous solution of [Pd(NH3)4](NO3)2 and Na3[Rh(NO2)6] compounds. Both pure and La-doped aluminum oxides were used as a support. The catalysts showed very close activity under stoichiometric and reductive conditions, but were different in terms of thermal stability being tested in a prompt thermal aging regime. UV–Vis and luminescence spectroscopies were found to be informative for diagnostics of rhodium and palladium concentration and state, thus giving the possibility to follow the changes taking place with active components (migration, agglomeration, bulk diffusion).
关键词： Metal migration,Prompt thermal aging,UV–Vis spectroscopy,Three-way catalysts,Luminescence spectroscopy
更新于2025-09-09 09:28:46
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Reference Module in Chemistry, Molecular Sciences and Chemical Engineering || Application of Luminescence Spectroscopy in New Materials for Solar Energy Utilization
摘要： The most important problems of our age are the search of new energy sources and the ways to decrease the pollution from organic fuels. Solar energy could provide a partial solution to the problem. If luminescent solar concentrators (LSCs) will be applied to the existing and modern buildings a part of the problem could be solved. In the following I describe the principle of LSCs and the ways by which their efficiency can be achieved.
关键词： Luminescence Spectroscopy,Solar Energy,Lanthanides,New Materials,Luminescent Solar Concentrators,Surface Plasmons
更新于2025-09-09 09:28:46