copy and easy to authenticate) is the primary approach for resisting the increasing sophistication of counterfeiting. [1] Due to their visual identifiability, colorful light emissions of luminophors are considered to be ideal security elements. The luminescent patterns of banknotes under ultraviolet (UV) excitation are a well-known sample of this approach. In addition to the spatial spectral fingerprints displayed in emission colors, the excitation mode and emission lifetime of luminescence can be used as authentication information, providing higher coding levels. For example, photoluminescence (PL), upconversion luminescence (UCL), and long-lasting luminescence (LLL) are three quintessential modes for anticounterfeiting and information security. [2] The PL mode produces photons at longer wavelengths than the excitation wavelength, for example, downshifting UV excitation to visible emission. [3] The UCL mode converts longwavelength photons to short-wavelength ones, for example, in the upconversion of near-infrared (NIR) excitation to visible emission. [4] It is important to note that PL and UCL phenomena will disappear immediately once light excitation is stopped, showing a feature of pulse duration (so-called fluorescence). In contrast, LLL shows delayed initiation after the cessation of Optical characteristics of luminescent materials, including emission color (wavelength), lifetime, and excitation mode, play crucial roles in data communication and information security. Conventional luminescent materials generally display unicolor, unitemporal, and unimodal (occasionally bimodal) emission, resulting in low-level readout and decoding. The development of multicolor, multitemporal, and multimodal luminescence in a single material has long been considered to be a significant challenge. In this study, for the first time, the superior integration of colorful (red-orange-yellowgreen), bitemporal (fluorescent and delayed), and four-modal (thermo-/ mechano-motivated and upconverted/downshifted) emissions in a particular piezoelectric particle via optical multiplexing of dual-lanthanide dopants is demonstrated. The as-prepared versatile NaNbO 3 :Pr 3+ ,Er 3+ luminescent microparticles shown are particularly suitable for embedding into polymer films to achieve waterproof, flexible/wearable and highly stretchable features, and synchronously to provide multidimensional codes that can be visually read-out using simple and commonly available tools (including the LED of a smartphone, pen writing, cooling-heating stimuli, and ultraviolet/ near-infrared lamps). These findings offer unique insight for designing highly integrated stimuli-responsive luminophors and smart devices toward a wide variety of applications, particularly advanced anticounterfeiting technology.

.[1] The earliest formed crust on a single plate planet such as Mars should be preserved, deeply buried under subsequent surface materials. Mars' extensive cratering history would have fractured and disrupted the upper layers of this ancient crust. Large impacts occurring late in Martian geologic history would have excavated and exposed this deeply buried material. We report the compositional analysis of unaltered mafic Martian crater central peaks with high-resolution spectral data that was used to characterize the presence, distribution and composition of mafic mineralogy. Reflectance spectra of mafic outcrops are modeled with the Modified Gaussian Model (MGM) to determine cation composition of olivine and pyroxene mineral deposits. Observations show that central peaks with unaltered mafic units are only observed in four general regions of Mars. Each mafic unit exhibits spectrally unmixed outcrops of olivine or pyroxene, indicating dunite and pyroxenite dominated compositions instead of basaltic composition common throughout much of the planet. Compositional analysis shows a wide range of olivine Fo# ranging from Fo 60 to Fo 5 . This variation is best explained by a high degree of fractionation in a slowly cooling, differentiating magma body. Pyroxene analysis shows that all the sites in the Southern Highlands are consistent with moderately Fe-rich, low-Ca pyroxene. Mineral segregation in the ancient crust could be caused by cumulate crystallization and settling in a large, potentially global, lava lake or near surface plutons driven by a hypothesized early Martian mantle overturn.

Piezoluminescence has achieved enormous advancement in the field of stress sensors, and mechano-driven lightings and displays; however the existing piezoluminescent materials universally need the external dopants of lanthanide or transition metal ions to create efficient luminescence. Herein, we report a bright piezoluminescence in undoped piezoelectric semiconductor CaZnOS, which is multi-mechano-sensitive to ultrasonic vibration, friction, impact and compression. Our experimental and density functional theory computational investigations indicate that the intrinsic oxygen vacancies of VO2+, VO+ and VO0 act as luminescent centers and trap states in multi-colored components of luminescence. In addition to saving resources and protecting environment, our research is expected to open a door for design and development of self-piezoluminescent materials, thereby largely expanding our understanding of piezoluminescent mechanism and promoting further utilization of piezoluminescence.

No abstract

Thermal emission spectroscopy is used to determine the mineralogy of sandstone and mudstone rocks as part of an investigation of linear spectral mixing between sedimentary constituent phases. With widespread occurrences of sedimentary rocks on the surface of Mars, critical examination of the accuracy associated with quantitative models of mineral abundances derived from thermal emission spectra of sedimentary materials is necessary. Although thermal emission spectroscopy has been previously proven to be a viable technique to obtain quantitative mineralogy from igneous and metamorphic materials, sedimentary rocks, with natural variation of composition, compaction, and grain size, have yet to be examined. In this work, we present an analysis of the thermal emission spectral (~270–1650 cm−1) characteristics of a suite of 13 sandstones and 14 mudstones. X‐ray diffraction and traditional point counting procedures were all evaluated in comparison with thermal emission spectroscopy. Results from this work are consistent with previous thermal emission spectroscopy studies and indicate that bulk rock mineral abundances can be estimated within 11.2% for detrital grains (i.e., quartz and feldspars) and 14.8% for all other mineral phases present in both sandstones and mudstones, in comparison to common in situ techniques used for determining bulk rock composition. Clay‐sized to fine silt‐sized grained phase identification is less accurate, with differences from the known ranging from ~5 to 24% on average. Nevertheless, linear least squares modeling of thermal emission spectra is an advantageous technique for determining abundances of detrital grains and sedimentary matrix and for providing a rapid classification of clastic rocks.

Central peaks of impact craters contain materials exhumed from depth, and therefore, investigation of these materials provides clues to subsurface geology and mineralogy. A global spectral survey of central peaks of Martian impact craters between 10 and 200 km diameter was completed using Mars Odyssey Thermal Emission Imaging System (THEMIS) data. Twenty-six central peaks with distinctive spectral signatures from surrounding plains were identified and characterized with thermal infrared and visible/near-infrared data. The distribution of spectrally distinct central peaks (SDCPs) shows some degree of regional clustering, with most craters found in western Noachis Terra, Tyrrhena Terra, within the northern rim of Hellas Basin, and fewer in the northern lowlands. With the exception of four craters in western Noachis Terra, SDCPs contain only one spectrally distinct unit at THEMIS resolution (100 m/pixel). The maximum number of spectrally distinct units observed was three, in Jones and Ostrov craters. The western Noachis Terra SDCPs may expose crustal stratigraphies of multiple igneous compositions or impact materials from Argyre. In the highlands, most SDCP units are consistent with enrichments in olivine or pyroxene relative to surrounding plains, suggesting olivine and pyroxene basaltic lithologies; few are olivine and pyroxene poor. No spatial trend in spectrally derived compositions of SDCPs was observed. Three SDCPs contain THEMIS signatures consistent with high abundances of phyllosilicates, which may contain the most phyllosilicate-rich lithologies found in central peak-associated materials globally.

A variety of up-and-coming applications of piezoluminescence in artificial skins, structural health diagnosis, and mechano-driven lightings and displays recently have triggered an intense research effort to design and develop new piezoluminescent materials. In this work, we deduced and verified an efficient piezoluminescence in ferroelectric CaTiO:Pr long-persistent phosphor, in view of three fundamental elements forming piezoluminescence - piezoelectricity, luminescent centers and carrier traps. Under the stimulation of mechanical actions including compression and friction, CaTiO:Pr shows an intense red emission from D-H transition of Pr. On the basis of investigations on structural and optical characteristics especially photoluminescence, persistent luminescence and thermoluminescence, we finally proposed a possible piezoluminescent mechanism in CaTiO:Pr. Our research is expected to expand the horizon of existing piezoluminescent materials, accelerating the development and application of new materials.

Fine‐grained sedimentary deposits on planetary surfaces require quantitative assessment of mineral abundances in order to better understand the environments in which they formed. One way that planetary surface mineralogy is commonly assessed is through thermal emission (~6–50 µm) spectroscopy. To that end, we characterized the TIR spectral properties of compacted, very fine‐grained mineral mixtures of oligoclase, augite, calcite, montmorillonite, and gypsum. Nonnegative linear least squares minimization (NNLS) is used to assess the linearity of spectral combination. A partial least squares (PLS) method is also applied to emission spectra of fine‐grained synthetic mixtures and natural mudstones to assess its applicability to fine‐grained rocks. The NNLS modeled abundances for all five minerals investigated are within ±10% of the known abundances for 39% of the mixtures, showing the relationships between known and modeled abundance follow nonlinear curves. The poor performance of NNLS is due to photon transmission through small grains over portions of the wavelength range and multiple reflections in the volume. The PLS method was able to accurately recover the known abundances (to within ±10%) for 78–90% of synthetic mixtures and for 85% of the mudstone samples chosen for this study. The excellent agreement between known and modeled abundances is likely due to high absorption coefficients over portions of the thermal infrared (TIR) spectral range, and thus, combinations are linear over portions of the range. PLS can be used to recover abundances from very fine‐grained rocks from TIR measurements and could potentially be applied to landed or orbital TIR observations.