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External pressure is one of the key parameters to understand photoemission nanomaterials since the external pressure changes their photoproperties without introducing any chemical treatment. Here, we computationally elucidated the effects of the external pressure on structures, orbitals, photoproperties, and vibrational dynamics of a silicon vacancy (SiV) diamond nanoslab. We studied its attributes not only on the ground state at 0 K but also on the excited state around room temperature (RT) using an ab initio molecular dynamics simulation. We directly and mechanically pressed the SiV diamond nanoslab fluctuating around RT to mimic an actual external pressure usually generated in an anvil cell at RT. We found that the compression induces the shrunk SiV defect structures, the rearranged defect orbital energies, the switch of the optical transition from the SiV–SiV excitation to the nanoslab–SiV excitation, the hybridization of the SiV with nanoslab carbon (C) orbitals, and the blue shift and the smaller intensity of the spectra of the Si atom oscillation and the inner C–C bond vibration. The energies of absorption, emission, and zero-phonon line do not change monotonically but have the maxima below a 7%-compression. Especially, the absorption energy differs more between 0 K and RT as the compression increases, while the largest deviation between 0 K and RT in the emission energy appears below the 7%-compression. It is remarkable that all of these changes are caused only by the mechanical compression and that the compression differently pronounces the temperature effect. The obtained insights will provide a way to effectively control a split-vacancy center to be a promising single-photon source for nanoscale optical measurements of temperature and pressure in a compressed nanoscale material. [ABSTRACT FROM AUTHOR]

Success in photovoltaic power generation has raised a huge possibility in metal halide perovskites to exhibit excellent photodetection performance with the same physics of photocarrier generation, and their collection at terminal electrodes is employable with less defect-assisted carrier recombination loss. To test this, nanostructured Ruddlesden–Popper (RP)-layered perovskite series were synthesized based on a cyclic organic moiety and Br– halide, resulting in (CH)2(MA)n−1PbnBr3n+1 [where CH2-(1-cyclohexenyl) ethylamine, MAmethylammonium, Brbromine, and n = 1–4], to explore how best its mono-to-few layer (n) 2D and quasi 2D-structures can offer photodetection performance with maximum absorbance in the unexplored blue-to-green band gap RP perovskites with maximum stability. Thermogravimetric analysis revealed that the very stable nature of these RP perovskites is accompanied by a linear rise in the structural phase transition temperatures, which range from 270 °C (CH)2PbBr4 (n = 1) to 304 °C (CH)2(MA)3Pb4Br13. The RP perovskites (CH)2(MA)n−1PbnBr3n+1 (n = 1–4) demonstrated sharp exciton emission peaks from blue (∼408 nm) to green (∼528 nm). The X-ray diffraction results confirmed the highly crystalline nature of quasi-2D perovskite thin films. Layer-dependent photoluminescence studies exhibit strong room-temperature exciton photoluminescence and high carrier lifetime. The transient photocurrent measurements for (CH)2(MA)3Pb4Br13 (n = 4) RP perovskite thin films show nearly six times the bias voltage changed from 1 to 5 V at 405 nm laser light excitation. In addition, with respect to performance, the (CH)2(MA)3Pb4Br13 photodetector has shown the highest responsivity (67.2 mA/W), ultrafast transient photocurrent response (122 nA), and high EQE (20.6%) as compared to (CH)2(MA)2Pb3Br10 (n = 3) and (CH)2(MA)-Pb2Br7 (n = 2) in ambient temperature. [ABSTRACT FROM AUTHOR]

Understanding optical absorption in silicon nitride is crucial for cutting-edge technologies like photonic integrated circuits, nanomechanical photothermal infrared sensing and spectroscopy, and cavity optomechanics. Yet, the origin of its strong dependence on the film deposition and fabrication process is not fully understood. This Letter leverages nanomechanical photothermal sensing to investigate optical extinction κ ext at a 632.8 nm wavelength in low-pressure chemical vapor deposition (LPCVD) SiN strings across a wide range of deposition-related tensile stresses (200-850 MPa). Measurements reveal a reduction in κ ext from 10 3 to 10 1 ppm with increasing stress, correlated to variations in Si/N content ratio. Within the band-fluctuations framework, this trend indicates an increase of the energy bandgap with the stress, ultimately reducing absorption. Overall, this study showcases the power and simplicity of nanomechanical photothermal sensing for low absorption measurements, offering a sensitive, scattering-free platform for material analysis in nanophotonics and nanomechanics.

The large-scale application of aqueous Al-air batteries is highly restricted by the performance of Al anodes. The severe self-corrosion and hydrogen evolution of the Al anode in a concentrated alkaline electrolyte are the main reason. Here, aimed at relieving side reactions and enhancing the utilization of metal Al, we propose a hybrid electrolyte additive of 2-mercaptobenzothiazole (MBT) and ZnO to form a protective film at the anode/electrolyte interface and to decrease the hydrogen evolution active site. The strong absorption capability of MBT on the metal surface, along with the reduced Zn-containing layer, enables a compact protective film with high hydrogen evolution potential on the Al surface. With this benefit, the hydrogen evolution reaction (HER) inhibition efficiency is up to 83.58%, endowing a superior Al-air battery with an energy density of 2376.71 Wh kg Al -1 under a current density of 25 mA cm -2 . The conception of constructing a hybrid protective film on the metal surface not only favors the development of metal-air batteries but also facilitates metal corrosion protection.

Covalent organic framework (COF) aerogels with functional groups offer exceptional processability and functionality for various applications. These hierarchical porous materials combine the advantages of COFs with the benefits of aerogels, overcoming the limitations of conventional insoluble and nonfusible COF powders. However, achieving both high crystallinity and shape retention remains a challenge for functionalized COF aerogels. In this work, we develop a novel and general solvent substitution method for the one-step synthesis of formyl-functionalized COF aerogels without harsh vacuum conditions. These aerogels exhibit excellent processing capabilities, superior mechanical strength, and enhanced functionality. As a proof-of-concept, they were used in adsorption and lithium metal battery applications, significantly maximizing the structural advantages of COFs, e.g.: (i) the hierarchical porous structure is fully wetted by the electrolyte to form continuous transport channels; (ii) the polar groups, which are easier to be acquired, help in desolvation and transfer of Li + ; (iii) the regular pore structures stabilize deposition of Li + and inhibit the growth of lithium dendrites. These combined benefits contribute to a lighter battery with improved energy density and enhanced safety.

Whispering-gallery-mode (WGM) resonators are powerful instruments for single-molecule sensing in biological and biochemical investigations. WGM sensors leveraged by plasmonic nanostructures, known as optoplasmonic sensors, provide sensitivity down to single atomic ions. In this article, we describe that the response of optoplasmonic sensors upon the attachment of single protein molecules strongly depends on the intensity of WGM. At low intensity, protein binding causes red shifts of WGM resonance wavelengths, known as the reactive sensing mechanism. By contrast, blue shifts are obtained at high intensities, which we explain as thermo-optoplasmonic (TOP) sensing, where molecules transform absorbed WGM radiation into heat. To support our conclusions, we experimentally investigated seven molecules and complexes; we observed blue shifts for dye molecules, amino acids, and anomalous absorption of enzymes in the near-infrared spectral region. As an example of an application, we propose a physical model of TOP sensing that can be used for the development of single-molecule absorption spectrometers.

Broadband light absorbers are attractive for their applications in photodetection and photothermic conversion. Metal black absorbers are highly nanoscale porous deposits in the presence of inert gas and exhibit nanoscale structure. Silver nanoparticles have attracted intensive research interest because of their distinctive electrical and optical properties. Here, we fabricated a number of silver black films with nanoscale thicknesses under various gas ambient atmospheres (He and Ar). Our aim is to fabricate broadband absorbers with high absorption performance from the visible-to-mid-IR (MIR) spectral range and investigate their aging behaviors. The He-ambient silver black film exhibited average absorption coefficients of 3.17, 2.27, and 1.81 μm–1 in the visible, near-IR (NIR), and MIR ranges, respectively, with the highest value of 6.50 μm–1 at a wavelength of 357 nm. Those of the Ar-ambient film were 0.48, 0.51, and 0.443 μm–1 in visible, NIR, and MIR ranges, respectively. The absorption coefficients of the He-ambient film were much higher than those of the Ar-ambient film, which were very promising candidates as broadband absorbers. Moreover, metal black films suffered from aging phenomena because of their nanoscale porous structure. The long-term stability of the optical properties was worthy of attention for applications. Therefore, the room temperature aging behaviors of nanoscale-thick silver black films were investigated. Comparative analyses of the atomic content before/after aging demonstrated that the aging was attributed to crystallization, deliquescence, and oxidation. Comparative analyses of the absorption and photothermal response characteristics before/after aging were also performed. The results demonstrated that the nanoscale-thick silver black films possessed great absorption stability in the visible-to-MIR range and photothermal response stability, which can provide valuable reference for applications of broadband absorbers such as IR dynamic scene generation. [ABSTRACT FROM AUTHOR]

Material absorption is a key limitation in nanophotonic systems; however, its characterization is often obscured by scattering and diffraction. Here we show that nanomechanical frequency spectroscopy can be used to characterize material absorption at the parts per million level and use it to characterize the extinction coefficient κ of stoichiometric silicon nitride (Si 3 N 4 ). Specifically, we track the frequency shift of a high- Q Si 3 N 4 trampoline in response to laser photothermal heating and infer κ from a model including stress relaxation and both conductive and radiative heat transfer. A key insight is the presence of two thermalization time scales: rapid radiative cooling of the Si 3 N 4 film and slow parasitic heating of the Si chip. We infer κ ∼ 0.1-1 ppm for Si 3 N 4 in the 532-1550 nm wavelength range, matching bounds set by waveguide resonators. Our approach is applicable to diverse photonic materials and may offer new insights into their potential.

Storage lipids are an important compartment in the bioaccumulation of neutral organic compounds. Reliable models for predicting storage lipid-water and storage lipid-air partition coefficients ( K i slip/w and K i slip/a ), as well as their temperature dependence, are considered useful. Polyparameter linear free energy relationships (PP-LFERs) are accurate, general, and mechanistically clear models for predicting partitioning-related physicochemical quantities. About a decade ago, PP-LFERs were calibrated for K i slip/w at the physiological temperature of 37 °C. However, to date, a comprehensive collection and sufficiently reliable PP-LFERs for K i slip/w and K i slip/a at the most common standard temperature of 25 °C are still lacking. In this study, experimentally based K i slip/w and/or K i slip/a values at 25 °C for 278 compounds were extensively collected or converted from the literature. Subsequently, PP-LFERs were calibrated for K i slip/w and K i slip/a at 25 °C, performing well over 10 orders of magnitude with root-mean-square errors of 0.17-0.21 log units for compounds with reliable descriptors. Furthermore, standard internal energy changes of transfer from water or air to storage lipids for 158 compounds were derived and used to calibrate PP-LFERs for estimating the temperature dependence of K i slip/w or K i slip/a . Additionally, using PP-LFERs, low-density polyethylene was confirmed to be a better storage lipid analogue than silicone and polyoxymethylene in the equilibrium passive sampling of nonpolar and H-bond acceptor polar compounds.

The photoluminescence spectrum of a single-layer boron nitride remains elusive, marked by enigmatic satellites that hint at significant but unidentified exciton-phonon coupling. Here, by employing a first-principles approach based on the many-body cumulant expansion of the charge response, we calculate the optical absorption and photoluminescence of a single-layer boron nitride. We identify the specific exciton-phonon scattering channels and unravel their impact on the optical absorption and photoluminescence spectra, thereby providing an interpretation of the experimental features. Finally, we show that, even in a strongly polar material such as h-BN monolayer, the electron-hole interaction responsible for the excitonic effect results in the cancellation of the Frölich interaction at small phonon momenta. This effect is captured only if the invariance of the exciton-phonon matrix elements under unitary transformations in the Bloch function manifold is preserved in the calculation.

Aging and stress have contributed to the development of memory disorders. Phe-Pro-Phe (FPF) was identified with high stability by mass spectrometry from simulated gastrointestinal digestion and everted gut sac products of the Antarctic krill peptide Ser-Ser-Asp-Ala-Phe-Phe-Pro-Phe-Arg (SSDAFFPFR) which was found to have a positive impact on memory enhancement. This study investigated the digestive stability, absorption, and memory-enhancing effects of FPF using nuclear magnetic resonance spectroscopy, simulated gastrointestinal digestion, in vivo fluorescence distribution analysis, mouse behavioral experiments, acetylcholine function, Nissl staining, immunofluorescence, and immunohistochemistry. FPF crossed the blood-brain barrier into the brain after digestion, significantly reduced shock time, working memory errors, and reference memory errors, and increased the recognition index. Additionally, FPF elevated ACh content; Nissl body counts; and CREB, SYN, and PSD-95 expression levels, while reducing AChE activity ( P < 0.05). This implies that FPF prevents scopolamine-induced memory impairment and provides a basis for future research on memory disorders.

Upon dissolution, amorphous solid dispersions (ASDs) of poorly water-soluble compounds can generate supersaturated solutions consisting of bound and free drug species that are in dynamic equilibrium with each other. Only free drug is available for absorption. Drug species bound to bile micelles, polymer excipients, and amorphous and crystalline precipitate can reduce the drug solute's activity to permeate, but they can also serve as reservoirs to replenish free drug in solution lost to absorption. However, with multiple processes of dissolution, absorption, and speciation occurring simultaneously, it may become challenging to understand which processes lead to an increase or decrease in drug solution concentration. Closed, nonsink dissolution testing methods used routinely, in the absence of drug removal, allow only for static equilibrium to exist and obscure the impact of each drug species on absorption. An artificial gut simulator (AGS) introduced recently consists of a hollow fiber-based absorption module and allows mass transfer of the drug from the dissolution media at a physiological rate after tuning the operating parameters. In the present work, ASDs of varying drug loadings were prepared with a BCS-II model compound, ketoconazole (KTZ), and hypromellose acetate succinate (HPMCAS) polymer. Simultaneous dissolution and absorption testing of the ASDs was conducted with the AGS, and simple analytical techniques were utilized to elucidate the impact of bound drug species on absorption. In all cases, a lower amount of crystalline precipitate was formed in the presence of absorption relative to the nonsink dissolution "control". However, formation of HPMCAS-bound drug species and crystalline precipitate significantly reduced KTZ absorption. Moreover, at high drug loading, inclusion of an absorption module was shown to enhance ASD dissolution. The rank ordering of the ASDs with respect to dissolution was significantly different when nonsink dissolution versus AGS was used, and this discrepancy could be mechanistically elucidated by understanding drug dissolution and speciation in the presence of absorption.

Studies on the bioavailability, serum levels, and absorption of hydrolyzable tannin compounds are lacking. In this study, we performed a pharmacokinetic trial, measured the serum levels of compounds in broilers that were reared with different feed added or not with tannins, and tested the digestibility of tannins throughout the intestinal tract. Only gallic acid and 4- O -methyl gallic acid were found in the serum. Moreover, gallic acid showed a 41.8% absolute oral bioavailability and a 72.3% relative bioavailability of gallic acid from chestnut extract compared to the standard. The rapid metabolization caused alternating serum levels during the day and night. These patterns were not affected by the feed type or the previous addition of tannins in the feed. The absorption and metabolization in the intestines occurred gradually throughout the intestinal tract. The latter was true for gallic acid as well as ellagic acid, which was not found in the serum. We can conclude that components from chestnut tannins are absorbed throughout all components of the intestinal tract and are eliminated quickly with little interaction from the feed and previous addition of tannins. Moreover, ellagic acid seems to be absorbed but would remain accumulated in the intestinal tissue or be metabolized by the microbiome.

Two-dimensional (2D) semiconductors have attracted great attention as a novel class of gain materials for low-threshold, on-chip coherent light sources. Despite several experimental reports on lasing, the underlying gain mechanism of 2D materials remains elusive due to a lack of key information, including modal gain and the confinement factor. Here, we demonstrate a novel approach to directly determine the absorption coefficient of monolayer WS 2 by characterizing the whispering gallery modes in a van der Waals microdisk cavity. By exploiting the cavity's high intrinsic quality factor of 2.5 × 10 4 , the absorption coefficient spectrum and confinement factor are experimentally resolved with unprecedented accuracy. The excitonic gain reduces the WS 2 absorption coefficient by 2 × 10 4 cm -1 at room temperature, and the experimental confinement factor is found to agree with the theoretical prediction. These results are essential for unveiling the gain mechanism in emergent, low-threshold 2D-semiconductor-based laser devices.

Iron is one of the trace mineral elements, and iron deficiency is a common phenomenon that negatively influences human health. Food-derived iron supplements were considered excellent candidates for improving this syndrome. In this work, oyster-protein hydrolysates (OPH) and ferrous chloride successfully formed the OPH-Fe complex (6 mg/mL, 40 °C, 30 min), where the main binding sites involved were the carboxyl and amino groups. The OPH-Fe complex showed no obvious changes in the secondary structure, while the iron changed the morphological appearance and also showed fluorescence quenching, an ultraviolet shift, and an increase in size distribution. The OPH-Fe complex showed better dynamic absorption of iron (64.11 μmol/L) than ferrous sulfate (46.90 μmol/L), and the medium dose had better protective effects against iron-deficiency anemia in vivo . Three representative peptides (DGKGKIPEE, FAGDDAPRA, and VLDSGDGVTH) that were absorbed intact were identified. This experiment provided a theoretical foundation for further study of the digestion and absorption of the OPH-Fe complex.

Lignans are a group of phenolic compounds found in plant-based diets. The human body can obtain lignans through diet, which are then metabolized into enterolignans. The enterolignans have been linked to several health benefits, including anticancer, anti-inflammatory, antioxidant effects, and estrogen effects. This review explores the relationship between the estrogenic effects of lignans and health. This review not only considers the estrogen-like activity of lignans but also discusses the safe dosage of lignans at different life stages. In addition, this review also identified other types of bioactive compounds that can act synergistically with lignans to promote health. Studies have shown that lignan administration during pregnancy and lactation reduces the risk of breast cancer in offspring. Further studies are needed to investigate the estrogenic safety effects of lignan on pregnant women and children. Whether lignans combine with other nutrients in complex food substrates to produce synergistic effects remains to be investigated. This review provides a basis for future studies on the safe dose of lignan and recommended dietary intake of lignan. We believe that the acquired as discussed here has implications for developing dietary therapies that can promote host nutrition and modulate estrogenic diseases.

Drug delivery systems (DDS) control the amount, rate, and site of administration of drug substances in the body as well as their release and ADME (absorption, distribution, metabolism, excretion). Among the various types of DDS, amount-controlled DDS for solubilization and absorption increase the bioavailability. Time- and amount-controlled DDS are controlled release formulations classified as (1) membrane-type, (2) matrix-type, (3) osmotic-type, and (4) ion-exchange type. Timed-release formulations also control the time and amount of release and the absorption of drugs. Site- and amount-controlled DDS are characterized by colonic delivery and intestinal lymph-targeting to improve release and ADME of drug substances. Finally, site-, time-, and amount-controlled DDS are gastroretentive formulations and local delivery in the oral cavity to improve site retention, release, and ADME of drugs. DDS can enhance efficacy, reduce adverse effects, and optimize the dosing frequency of various drug products to increase patient value. This review focuses on patient value and industrial considerations of launched oral DDS. We provide a technological overview of candidate and marketed DDS, as well as the pros/cons of the technologies for industrialization with consideration to excipients, manufacturing, and storage stability. Moreover, to demonstrate the usefulness of the technology and support the selection and development of the best technologies for patients, we also describe patient value from clinical studies and analyses, particularly with regard to increased new medical options, higher efficacy, reduced adverse effects, reduced number of doses and clinic visits, easier administration, higher quality of life, greater adherence, and satisfaction.

Indium phosphide colloidal quantum dots (CQDs) are the main alternative for toxic and restricted Cd based CQDs for lighting and display applications. Here we systematically report on the size-dependent optical absorption, ensemble, and single particle photoluminescence (PL) and biexciton lifetimes of core-only InP CQDs. This systematic study is enabled by improvements in the synthesis of InP CQDs to yield a broad size series of monodisperse core-only InP CQDs with narrow absorption and PL line width and significant PL quantum yield.

The hybrid technology of CO 2 capture-mineral carbonation (CCMC) using alkaline streams has emerged in recent years. However, thus far, there has been no comprehensive study revealing the mechanisms of the simultaneous CCMC process regarding the choice of amine types and sensitivity of parameters. Combining with the analysis of multistep reaction mechanisms for different amines, we investigated a representative from each category in CCMC using calcium chloride to simulate the alkaline resource after leaching, i.e., primary (ethanolamine, MEA), secondary (diisopropanolamine, DIPA), tertiary (diethylethanolamine, DEAE), and triamine (diethylenetriamine, DETA), respectively. In the adsorption step, increasing the amine concentration beyond 2 mol/L reduced the absorption efficiency of DEAE due to the hydration mechanism, motivating a rational choice of concentration. In CCMC sections, when the amine concentration increased, only DEAE exhibited an increased carbonation efficiency of up to 100%, while DETA showed the lowest conversion. The carbonation of DEAE demonstrated the least sensitivity to temperature. The crystal transformation experiments suggested that over time, the produced vaterite could completely transform to calcite or aragonite, except those from DETA. Thus, with rationally chosen conditions, DEAE was demonstrated ideal for CCMC. These findings obtained in this work provided a theoretical foundation for designing future CCMC processes.

The photodeamination reaction of the anthrol molecule generating the high-activity quinone methide intermediate has been investigated ( J. Org. Chem. 2017, 82, 6006-6021), though lacking careful explanation for its reaction mechanism. In our research, the mechanism of the anthrol molecule photodeamination induced by excited-state intramolecular proton transfer was reported for the first time. Absorption and emission spectra calculated for the work presented here agreed well with experimental results. To propose a molecular-level explanation of the photodeamination reaction, we calculated bond parameters, corresponding infrared vibrational frequencies, Mayer bond orders, and visualized frontier molecular orbitals of different molecules, and the hydrogen bond strengthening behavior in excited states was confirmed, enhancing the excited state intramolecular proton transfer of the anthrol molecule. Moreover, we concluded that photoisomerization weakened the bond strength between nitrogen and carbon atoms, which promoted the photodeamination reaction. Finally, for visually and quantificationally revealing the photodeamination mechanism, we have established the three-dimensional potential energy surfaces for the deamination reaction in different electronic states and calculated the corresponding reaction Gibbs free energies, it can be confirmed that the photodeamination reaction of the anthrol molecule must be induced by a proton transfer reaction in the excited state. [ABSTRACT FROM AUTHOR]

Stereospecific recognition of chiral molecules is ubiquitous in chemical and biological systems, thus leading to strong demand for the development of enantiomeric drugs, enantioselective sensors, and asymmetric catalysts. In this study, we demonstrate the ratio of D-Cys and L-Cys playing an important role in determining the optical properties and the structures of self-assembled Cys-Au(I) supramolecules prepared through a simple reaction of tetrachloroaurate(III) with chiral cysteine (Cys). The irregularly shaped -[D-Cys-Au(I)]n- or - [L-Cys-Au(I)]n- supramolecules with a size larger than 500 nm possessing strong absorption in the near-UV region and chiroptical characteristics were only obtained from the reaction of Au(III) with D-Cys or L-Cys. On the other hand, spindle-shaped -[D/L-Cys-Au(I)]n- supramolecules were formed when using Au(III) with mixtures of D/L-Cys. Our results have suggested that Au(I)···Au(I) aurophilic interactions, and stacked hydrogen bonding and zwitterionic interactions between D/L-Cys ligands are important in determining their structures. The NaBH4- mediated reduction induces the formation of photoluminescent gold nanoclusters (Au NCs) embedded in the chiral -[D-Cys- Au(I)]n- or -[L-Cys-Au(I)]n- supramolecules with a quantum yield of ca. 10%. The as-formed Au NCs/-[D-Cys-Au(I)]n- and Au NCs/-[L-Cys-Au(I)]n- are an enantiospecific substrate that can trap L-carnitine and D-carnitine, respectively, and function as a nanomatrix for surface-assisted laser desorption/ionization mass spectrometry (LDI-MS). The high absorption efficiency of laser energy, analyte-binding capacity, and homogeneity of the Au NCs/-[Cys-Au(I)]n- allow for quantitation of enantiomeric carnitine down to the micromolar regime with high reproducibility. The superior efficiency of the Au NCs/-[DCys- Au(I)]n- substrate has been further validated by quantification of L-carnitine in dietary supplements with accuracy and precision. Our study has opened a new avenue for chiral quantitation of various analytes through LDI-MS using metal nanocomposites consisting of NCs and metal-ligand complexes. [ABSTRACT FROM AUTHOR]

Levitation optomechanics exploits the unique mechanical properties of trapped nano-objects in vacuum to address some of the limitations of clamped nanomechanical resonators. In particular, its performance is foreseen to contribute to a better understanding of quantum decoherence at the mesoscopic scale as well as to lead to novel ultrasensitive sensing schemes. While most efforts have focused so far on the optical trapping of low-absorption silica particles, further opportunities arise from levitating objects with internal degrees of freedom, such as color centers. Nevertheless, inefficient heat dissipation at low pressures poses a challenge because most nano-objects, even with low-absorption materials, experience photodamage in an optical trap. Here, by using a Paul trap, we demonstrate levitation in vacuum and center-of-mass feedback cooling of a nanodiamond hosting a single nitrogen-vacancy center. The achieved level of motion control enables us to optically interrogate and characterize the emitter response. The developed platform is applicable to a wide range of other nano-objects and represents a promising step toward coupling internal and external degrees of freedom. [ABSTRACT FROM AUTHOR]

Recent advances in the ytterbium doping of CsPbX3 (X = Cl or Cl/Br) nanocrystals have presented exciting new opportunities for their application as downconverters in solar-energy-conversion technologies. Here, we describe a hot-injection synthesis of Yb3+:CsPbCl3 nanocrystals that reproducibly yields sensitized Yb3+ 2F5/2 → 2F7/2 luminescence with near-infrared photoluminescence quantum yields (PLQYs) well over 100% and almost no excitonic luminescence. Near-infrared PLQYs of 170% have been measured. Through a combination of synthesis, variable-temperature photoluminescence spectroscopy, and transient-absorption and time-resolved photoluminescence spectroscopies, we show that the formation of shallow Yb3+-induced defects play a critical role in facilitating a picosecond nonradiative energy-transfer process that de-excites the photoexcited nanocrystal and simultaneously excites two Yb3+ dopant ions, i.e., quantum cutting. Energy transfer is very efficient at all temperatures between 5 K and room temperature but only grows more efficient as the temperature is elevated in this range. Our results provide insights into the microscopic mechanism behind the extremely efficient sensitization of Yb3+ luminescence in CsPbX3 nanocrystals, with ramifications for future applications of high-efficiency spectral-conversion nanomaterials in solar technologies. [ABSTRACT FROM AUTHOR]

The inhibition of radiative losses in dark plasmon modes allows storing electromagnetic energy more efficiently than in far-field excitable bright-plasmon modes. As such, processes benefiting from the enhanced absorption of light in plasmonic materials could also take profit of dark plasmon modes to boost and control nanoscale energy collection, storage, and transfer. We experimentally probe this process by imaging with nanoscale precision the hot-electron driven desorption of thiolated molecules from the surface of gold Fano nanostructures, investigating the effect of wavelength and polarization of the incident light. Spatially resolved absorption maps allow us to show the contribution of each element of the nanoantenna in the hot-electron driven process and their interplay in exciting a dark plasmon mode. Plasmon-mode engineering allows control of nanoscale reactivity and offers a route to further enhance and manipulate hot-electron driven chemical reactions and energy-conversion and transfer at the nanoscale. [ABSTRACT FROM AUTHOR]

In this work, we experimentally demonstrate metasurface-enhanced photoresponse in organic photodetectors. We have designed and integrated a metasurface with broadband functionality into an organic photodetector, with the goal of significantly increasing the absorption of light and generated photocurrent from 560 up to 690 nm. We discuss how the metasurface can be integrated with the fabrication of an organic photodiode. Our results show large gains in responsivity from 1.5× to 2× between 560 and 690 nm. [ABSTRACT FROM AUTHOR]

The nonlinear optical response of some O-doped polycyclic aromatic hydrocarbons (PAHs) is systematically investigated in the present work aiming to understand the influence of structural effects on their nonlinear optical response. In that view, the third-order nonlinear optical properties of these PAHs were measured under 4 ns visible (532 nm) and infrared (1064 nm) laser excitation. The O-doped PAHs were found to exhibit large saturable absorption and negative sign nonlinear refraction under visible excitation, increasing both with the addition of naphthalene units and with the number of O atoms. Their nonlinear optical response was found to be negligible under infrared excitation. Similar measurements performed on thin films of these PAHs have shown that they maintain their large nonlinear optical response even in the solid state, confirming their high potential for optoelectronic and photonic applications. [ABSTRACT FROM AUTHOR]

Bismuth-based solar absorbers have recently garnered attention due to their promise as cheap, nontoxic, and efficient photovoltaics. To date, however, most show poor efficiencies far below those seen in commercial technologies. In this work, we investigate two such promising materials, BiSI and BiSeI, using relativistic first-principles methods with the aim of identifying their suitability for photovoltaic applications. Both compounds show excellent optoelectronic properties with ideal band gaps and strong optical absorption, leading to high predicted device performance. Using defect analysis, we reveal the electronic and structural effects that can lead to the presence of deep trap states, which may help explain the prior poor performance of these materials. Crucially, detailed mapping of the range of experimentally accessible synthesis conditions allows us to provide strategies to avoid the formation of killer defects in the future. [ABSTRACT FROM AUTHOR]

Rare earth fluoride carbonates have been proven to be potential deep-ultraviolet optical materials, but lacked the systematic study on phase stability domains to guide synthesis. In this work, detailed investigations of the Na2CO3–GdF3–H2O system have been done in subcritical hydrothermal conditions. A series of sodium-rare earth carbonates crystals NaGdCO3F2 (1), Na2GdCO3F3 (2), Na3Gd(CO3)3 (3), and Na3Gd(CO3)3·6H2O (4) have been synthesized. NaGdCO3F2 (1) is composed of a three-dimensional (3-D) [GdCO3F2]− framework with Na+ as the charge balance cation. Na2GdCO3F3 (2) showed two-dimensional (2-D) [GdCO3F3]2– layers along the c-axis and further bridged by Na+ to form a 3-D framework. Na3Gd(CO3)3 (3) is made up of alternately stacked layers [Na(CO3)2]∞ along the a-axis and [Na2Gd(CO3)2]∞ in the bc plane, forming a 3-D framework. Na3Gd(CO3)3·6H2O (4) exhibits an intricate 3-D structure composed of a [Gd(CO3)3(H2O)3]3– complex and bridging Na+ ions. The results from the UV–vis diffuse reflectance spectroscopy study indicated that the short-wavelength absorption edge of all four compounds were below 200 nm, suggesting that they are potential deep-ultraviolet optical materials. Powder second harmonic generation measurements indicated that the compounds 3 and 4 are phase-matchable (type I), and they exhibit relatively strong second harmonic generation responses of approximately 3 and 2 times that of KH2PO4 (KDP). [ABSTRACT FROM AUTHOR]

We report here a new ternary solvated (perylene-TCNB)⋅2THF cocrystal, which can transform into binary perylene-TCNB cocrystal reversibly by successive desorption or absorption of THF solvent. As a consequence, macroscopic mechanical bending would be realized when repeated stimulation with THF solvent. The present results clearly demonstrated that solvent induced mechanical bending is driven by structural change at the molecular scale. Such solvatomechanical bending behavior is clearly revealed for the first time. [ABSTRACT FROM AUTHOR]

A series of bis-BN ullazine derivatives, including the parent species, were synthesized in a small number of steps from commercially available materials. X-ray crystallographic analysis revealed that bis-BN ullazines have rigid and planar frameworks. Most of the bis-BN ullazines are stable toward air and moisture. In addition, the absorption and emission bands of these ullazines are blue-shifted, compared to those of their carbonaceous ullazine analogs. [ABSTRACT FROM AUTHOR]

We demonstrate a simple, but efficient, approach for improving the semiconducting performances of DPP-based conjugated D-A polymers. This approach involves the replacement of one bulky branching alkyl chain with the linear one at each DPP unit in regular polymer PDPPSe-10 and PDPPSe-12. The UV-vis absorption, Raman spectra, PDS data, and theoretical calculations support that the replacement of bulky branching chains with linear ones can weaken the steric hindrance, and accordingly conjugated backbones become more planar and rigid. GIWAXS data show that the incorporation of linear alkyl chains as in PDPPSe-10 and PDPPSe-12 is beneficial for side-chain interdigitation and interchain dense packing, leading to improvement of interchain packing order and thin film crystallinity by comparing with PDPPSe, which contains branching alkyl chains. On the basis of field-effect transistor (FET) studies, charge mobilities of PDPPSe-10 and PDPPSe-12 are remarkably enhanced. Hole mobilities of PDPPSe-10 and PDPPSe-12 in air are boosted to 8.1 and 9.4 cm2 V-1 s-1, which are about 6 and 7 times, respectively, than that of PDPPSe (1.35 cm2 V-1 s-1). Furthermore, both PDPPSe-10 and PDPPSe-12 behave as ambipolar semiconductors under a nitrogen atmosphere with increased hole/electron mobilities up to 6.5/0.48 cm2 V-1 s-1 and 7.9/0.79 cm2 V-1 s-1, respectively. [ABSTRACT FROM AUTHOR]

Perovskite nanocrystals have shown themselves to be useful for both absorption- and emission-based applications, including solar cells, photodetectors, and LEDs. Here we present a new class of size-, composition-, and shape-tunable nanocrystals made from Tl3PbX5 (X= Cl, Br, I). These can be synthesized via colloidal methods to produce faceted spheroidal nanocrystals, and perovskite TlPbI3 nanowires. Crystal structures for the orthorhombic and tetragonal phase materials, for both pure and mixed halide species, are compared to the literature and also calculated from first-principles in VASP. We show the ability to tune the band gap by halide substitution to create materials that can absorb strongly between 250 and 450 nm. In addition, we show evidence of the confinement effect in pure halide Tl3PbBr5 nanocrystals suggesting size-tuning is possible as well. By tuning the band gap we can create materials with specific absorption spectra suitable for photodetection that display conduction and photoresponse properties similar to previously observed perovskite nanocrystals. We also observe weak emission consistent with indirect band-gap materials. Finally, we are able to demonstrate shape control in these materials, to give some insight into observable phase changes with varying reaction conditions, and to demonstrate the utility of the TlPbI3 perovskite nanowires as wide-band-gap photoconductors. These novel perovskite nanocrystalline materials can be expected to find applications in photodetectors, X-ray detectors, and piezoelectrics. [ABSTRACT FROM AUTHOR]

ε-iron oxide (ε-Fe2O3) has drawn attention from the viewpoints of high-density magnetic recording and high-frequency millimeter wave absorption. To date, chemical conversion from Fe3O4 (magnetite) to ε-Fe2O3 under wet process conditions have been difficult. Herein, we report that ε-Fe2O3 could be obtained from Fe3O4 using a nanosize wet process. In the present method, 10 or 16 nm sized Fe3O4 nanocrystals are used as the precursor. Fe3O4 nanocrystals are embedded in a silica matrix and subsequently sintered around 1000 °C in air, resulting in the chemical conversion from Fe3O4 to ε-Fe2O3 being confirmed. In the case of 10 nm sized Fe3O4 precursors, the sample consists of 16% ε-Fe2O3 and 84% γ-Fe2O3, whereas in the case of 16 nm sized Fe3O4 precursors, the sample consists of 24% ε-Fe2O3 and 76% γ-Fe2O3. The magnetic hysteresis loops of the samples are theoretically predicted using the large hysteresis loop of ε-Fe2O3 and the magnetization curve of super-paramagnetic γ-Fe2O3. The experimental and predicted hysteresis loops agree well. First-principles calculations suggest that Fe3O4 nanocrystals between 8 and 43 nm transform directly to ε-Fe2O3. Due to the strict size condition, the chemical conversion from Fe3O4 to ε-Fe2O3 is the first to be observed by a wet process. The nanosize wet process from Fe3O4 to ε-Fe2O3 should accelerate the development of highly functional hard magnetic ferrite ε-Fe2O3. [ABSTRACT FROM AUTHOR]

Here we present a new undergraduate laboratory that will introduce the concepts of time-resolved spectroscopy and provide insight into the natural time scales on which chemical dynamics occur through direct measurement. A quantitative treatment of the acquired data will provide a deeper understanding of the role of quantum mechanics and various phenomenological expressions in predicting kinetic rates for fluorescence, phosphorescence, and nonradiative decay mechanisms. This laboratory framework focuses specifically on spectroscopy in the nanosecond regime -- assisted by various steady-state spectroscopic techniques -- in order to fully characterize the electronic structure and the picosecond-to-microsecond dynamics of the dye eosin B. There is great flexibility in both the recommended lab duration (1 week to several months) and course level (upper-division to graduate) due to the numerous additional experiments that may be performed at varying levels of difficulty. The necessary components include pump and probe light sources, photodiode detectors, a programmable signal delay generator, and an oscilloscope for measurements with requisite resolution. The cost of building this experiment from scratch is less than $20,000 at the time of publication, but costs are expected to decrease over time and alternate excitation sources are available. Although this lab requires some expertise with optical spectroscopy to initially build and troubleshoot, use by students has been a straightforward and valuable experience. [ABSTRACT FROM AUTHOR]

We explore by means of modeling how absorptive-dispersive mixing between the second- and third-order terms modifies the imaginary χtotal(2) responses from air/water interfaces under conditions of varying charge densities and ionic strength. To do so, we use published Im(χ(2)) and χ(3) spectra of the neat air/water interface that were obtained either from computations or experiments. We find that the χtotal(2) spectral lineshapes corresponding to experimentally measured spectra contain significant contributions from both interfacial χ(2) and bulk χ(3) terms at interfacial charge densities equivalent to less than 0.005% of a monolayer of water molecules, especially in the 3100 to 3300 cm-1 frequency region. Additionally, the role of short-range static dipole potentials is examined under conditions mimicking brine. Our results indicate that surface potentials, if indeed present at the air/water interface, manifest themselves spectroscopically in the tightly bonded H-bond network observable in the 3200 cm-1 frequency range. [ABSTRACT FROM AUTHOR]

The synthesis of a new photocaged nicotinamide having an N-acyl carbamate linker and a p-hydroxyphenacyl (pHP) chromophore is described. The photophysical and photochemical studies showed an absorption maximum at λ = 330 nm and a quantum yield for release of 11% that are dependent upon both pH and solvent. While the acyl carbamate releases nicotinamide efficiently, a simpler amide linker was inert to photocleavage. This photocaged nicotinamide has significant advantages with respect to quantum yield, absorbance wavelength, rate of release, and solubility that make it the first practical example of a photocaged amide. [ABSTRACT FROM AUTHOR]

The molecular thermodynamics and kinetics of CO2 sorption in Polyethylenimine (PEI) melt have been investigated systematically using GCMC and MD simulations. We elucidate presence of significant structural and dynamic heterogeneity associated with the overall absorption process. CO2 adsorption in a PEI membrane shows a distinct two-stage process of a rapid CO2 adsorption at the interfaces (hundreds of picoseconds) followed by a significantly slower diffusion limited release toward the interior bulk regions of PEI melt (hundreds of nanoseconds to microseconds). The spatial heterogeneity of local structural features of the PEI chains lead to significantly heterogeneous absorption characterized by clustering and trapping of CO2 molecules that then lead to subdiffusive motion of CO2. In the complex interplay of interaction and entropy, the latter emerges out to be the major determining factor with significantly higher solubility of CO2 near the interfaces despite having lower density of binding amine groups. Regions having higher free-volume (entropically favorable) viz. interfaces, pores and loops demonstrate higher CO2 capture ability. Various local structural features of PEI conformations, for example, inter- and intrachain loops, pores of different radii, and di- or tricoordinated pores are explored for their effects on the varying CO2 adsorption abilities. [ABSTRACT FROM AUTHOR]

A series of hierarchical CoNi@SiO2@C composites were successfully fabricated through a workable procedure, and the content of carbon can be adjusted by modulating the additive dose of phenolic resin precursors. The compositions, microstructures, and magnetic characters of the obtained products were characterized in detail via XRD, SEM, XPS, and VSM detailedly. The results manifested that the urchin-like CoNi alloy particles were successively encapsulated with SiO2 and carbon coatings. The exploration into microwave absorbing performances demonstrated that wax-based hybrids containing 50 wt % CoNi@SiO2@C-3 are endowed with improved absorbing capability possessing the maximum RL value of −46.0 dB at 10.8 GHz with an effective absorption bandwidth of 5.6 GHz (from 7.1 to 12.7 GHz) for a layer thickness of only 2.2 mm. Moreover, in the wake of layer thicknesses varying from 1.5 to 5 mm, the effective absorbing bandwidth almost overlaps the whole C, X, and Ku wave bands. The remarkable microwave absorption performances are attributed to the joint outcome of the combination of dielectric and magnetic losses, the numerous interface polarizations and dipolar relaxations provided by their hierarchically multicomponent structures and the good impedance matching. [ABSTRACT FROM AUTHOR]

A new method for analytical applications based on the Maxwell-Wagner effect is proposed. Considering the interaction of carbonaceous materials with an electromagnetic field in the microwave frequency range, a very fast heating is observed due to interfacial polarization that results in localized microplasma formation. Such effect was evaluated in this work using a monomode microwave system, and temperature was recorded using an infrared camera. For analytical applications, a closed reactor under oxygen pressure was evaluated. The combination of high temperature and oxidant atmosphere resulted in a very effective self-ignition reaction of sample, allowing its use as sample preparation procedure for further elemental analysis. After optimization, a high sample mass (up to 600 mg of coal and graphite) was efficiently digested using only 4 mol L-1 HNO3 as absorbing solution. Several elements (Ba, Ca, Fe, K, Li, Mg, Na, and Zn) were determined by inductively coupled plasma optical emission spectrometry (ICP-OES). Accuracy was evaluated by using a certified reference material (NIST 1632b). Blanks were negligible, and only a diluted solution was required for analytes absorption preventing residue generation and making the proposed method in agreement with green chemistry recommendations. The feasibility of the proposed method for hard-to-digest materials, the minimization of reagent consumption, and the possibility of multi elemental analysis with lower blanks and better limits of detection can be considered as the main advantages of this method. [ABSTRACT FROM AUTHOR]

Ionic liquids are liquid salts at ambient temperature composed of organic cations and organic/inorganic anions. Outstanding physical and chemical properties of ionic liquids lead to increasing application in scientific and industrial field. Ionic liquids have been already investigated by different spectroscopic techniques, including terahertz (THz) time-domain spectroscopy. The usual THz frequency range extends up to 2-3 THz, a relatively narrow band, which can only show the intermolecular vibrational modes. Here, we report about broadband THz spectroscopy of ionic liquids up to 13 THz. Bandwidth of intermolecular absorption band presents an unexpected behavior and strong sharp intramolecular absorptions are shown. In addition, we found violation of the approximation of harmonic oscillator used to predict the peak shift of intermolecular absorption band. [ABSTRACT FROM AUTHOR]

The small absorption cross sections of most molecules led to the low sensitivity of traditional optical absorption spectroscopy. This obstacle might be overcome by applying the near-field plasmon resonance energy transfer (PRET) between plasmonic nanoparticle and surrounding molecules. In this work, we utilized PRET-based spectroscopy on single gold nanostars to study the specific biomolecule recognition and enzyme kinetics choosing biotin-SA pair and DNase I as models. By analyzing the changes of absorption spectra for black hole quencher 3 (BHQ3), derived from spectra difference, we explored the kinetics of specific biomolecule recognition and enzyme digestion in different physiological environment, and we found that the viscosities of media and the sizes of molecules play vital role in biomolecular recognition and enzyme digestion. Compared with the traditional optical absorption spectroscopy techniques, PRET-based spectroscopy offers a nanoscopic resolution owing to the small size of the probe, is more sensitive and achieves detection on the order of hundreds or even dozens of molecules, and can achieve high selectivity due to the specific biomolecular recognition. This method might be used in the fields of molecular diagnostics, drug discovery, cell systems, and clinical diagnostics. [ABSTRACT FROM AUTHOR]

To improve the performance of an absorption system, ionic liquids (ILs) have been chosen as additives to conventional working fluid (lithium bromide aqueous solution) in recent years. In this paper, 1-ethyl-3-methylimidazolium acetate ([Emim]Ac) was added to lithium bromide aqueous solution (mass ratio LiBr/[Emim]Ac = 3) to measure the vapor-liquid equilibrium (VLE) data of the ternary system. The experiment was conducted by means of boiling point method, at temperatures between 303.94 K and 405.41 K and mass fractions of absorbent between 0.20 and 0.60. The experimental data were regressed using an Antoine-type equation, and the average absolute relative deviation (AARD%) between the experimental and calculated values was 0.34%, which showed excellent accuracy and consistency. The experimental ternary system was compared with the conventional LiBr + H2O system and two other ternary systems from the literature; the result revealed that the experimental ternary system had lower vapor pressures, which will benefit the process of releasing latent heat in absorption cycles. [ABSTRACT FROM AUTHOR]

The performance of an ionic liquid with an aprotic heterocyclic anion (AHA-IL), trihexyl(tetradecyl)phosphonium 2-cyanopyrrolide ([P66614][2-CNPyr]), for CO2 capture has been evaluated considering both the thermodynamics and the kinetics of the phenomena. Absorption gravimetric measurements of the gas-liquid equilibrium isotherms of CO2-AHA-IL systems were carried out from 298 to 333 K and at pressures up to 15 bar, analyzing the role of both chemical and physical absorption phenomena in the overall CO2 solubility in the AHA-IL, as has been done previously. In addition, the kinetics of the CO2 chemical absorption process was evaluated by in situ Fourier transform infrared spectroscopy-attenuated total reflection, following the characteristic vibrational signals of the reactants and products over the reaction time. A chemical absorption model was used to describe the time-dependent concentration of species involved in the reactive absorption, obtaining kinetic parameters (such as chemical reaction kinetic constants and diffusion coefficients) as a function of temperatures and pressures. As expected, the results demonstrate that the CO2 absorption rate is mass-transfer-controlled because of the relatively high viscosity of AHA-IL. The AHA-IL was encapsulated in a porous carbon sphere (Encapsulated Ionic Liquid, ENIL) to improve the kinetic performance of the AHA-IL for CO2 capture. The newly synthesized AHA-ENIL material was evaluated as a CO2 sorbent with gravimetric absorption measurements. AHA-ENIL systems preserve the good CO2 absorption capacity of the AHA-IL but drastically enhance the CO2 absorption rate because of the increased gas-liquid surface contact area achieved by solvent encapsulation. [ABSTRACT FROM AUTHOR]