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[Display omitted] • A solar-induced regeneration technique for carbon dioxide adsorbents was invented. • MXene as the photothermal conversion component can significantly enhance the photoresponsive of aminosilica. • Aminosilica@MXene (7 wt%) achieves complete desorption at an illumination intensity of 2 kW·m−2. • Through multiple cycling tests, aminosilica@MXene (7 wt%) demonstrates outstanding recyclability. Due to the high energy consumption associated with regenerating adsorbents with high carbon dioxide adsorption capacity, utilizing renewable solar energy as an alternative to traditional thermal energy for photothermally regenerating adsorbents is a feasible approach. In this research, a solar-induced regeneration technique has been formulated, employing fumed silica as the framework, MXene as the photothermal conversion component, and (3-aminopropyl)triethoxysilane (APTES) as the site for carbon dioxide adsorption. The findings suggest that incorporating MXene can substantially enhance the photoresponsive and photothermal conversion properties of aminosilica. Beneath an brightening concentrated of 1 kW·m−2, aminosilica@MXene(7 wt%) reaches a maximum temperature of 76.8 °C, compared to only 53.4 °C when using aminosilica alone. Notably, aminosilica@MXene (7 wt%) achieves complete desorption at an illumination intensity of 2 kW·m−2. Through multiple cycling tests, aminosilica@MXene (7 wt%) demonstrates outstanding recyclability. As a result, using solar energy to power the adsorbent photothermal regeneration turns into a useful strategy for lowering the energy required for regeneration. [ABSTRACT FROM AUTHOR]

[Display omitted] • Visible light can induce the photodesorption of OH radicals on ice. • The wavelength-dependent photodesorption efficiency of OH is measured for the first time. • OH adsorption strengths and photodesorption cross sections affected the wavelength dependent photodesorption efficiency. • The possibility of measuring absorption spectra of free radicals adsorbed on ice. The photodesorption efficiencies of the hydroxyl (OH) radical from the water ice surface were measured in the range of 310–700 nm for the first time. Although isolated H 2 O molecules and OH radicals do not absorb visible photons, the photodesorption of OH interacting with the ice surface was found to occur by a one-photon process in the entire visible range. The photodesorption efficiency strongly depended on the wavelength, and the analyses of photodesorption cross sections indicated that only strongly bound OH radicals were desorbed at longer wavelengths, whereas both weakly and strongly bound OH radicals were desorbed at shorter wavelengths. [ABSTRACT FROM AUTHOR]

Four zircon Raman bands were previously calibrated to give consistent estimates of the accumulated self‐irradiation α‐dose in unannealed volcanic samples. Partial annealing of radiation damage produces inconsistent values because of differences in the relative annealing sensitivities. The damage estimates based on the external rotation band (DER) at ∼356 cm−1 and that based on the ν2(SiO4) band (D2) at ∼438 cm−1 are the most and least sensitive to damage annealing. The D2/DER‐ratio thus provides a numerical estimate of the extent of geologic annealing that a zircon sample has experienced. This ratio characterizes the thermal history of a zircon sample but also its state of radiation damage during the course of its geologic history, and thus the manner in which this state influences other thermochronologic methods. Meaningful interpretation of the zircon Raman age requires that the spectra are free of measurement artifacts. The major artifacts result from micrometer‐scale gradients of the damage densities within a zircon grain due to uranium and thorium zoning. The micrometer‐sized sampled volume may span different densities, producing overlapping spectra, causing apparent peak broadening, overestimated damage densities, and zircon Raman ages. The D3/D2‐ratio of the damage densities calculated from the ν3(SiO4) and ν2(SiO4) bands, most and least affected by overlap, is an efficient indicator of a meaningless signal. It reveals overlap in annealed and unannealed samples, because the used bands have similar responses to annealing. Multi‐band Raman maps can be converted to damage‐ratio maps for screening zircon mounts, and selecting spots for thermochronologic investigations. Plain Language Summary: Radioactive processes cause damage to the lattice of zircon crystals. This damage can be measured with a Raman instrument. Such measurements are important for methods determining the ages and thermal histories of zircon grains in rocks. Thus, the Raman measurements must be reliable and meaningful. This work proposes tools for detecting effects that hinder the interpretation of zircon Raman data. These effects are mixed signals and loss of damage due to exposure to elevated temperatures in the geologic environment. Zircon Raman spectra have different bands that respond differently to mixed signals and temperature. The ratio of the damage estimates from the least and most temperature‐sensitive bands thus indicates partial annealing. Raman spectra of zoned zircons often straddle areas with different lattice damage. Their overlapping signals cause artificial band broadening, and a damage overestimation. The ratio of the damage estimated from the least and the most affected bands identifies mixed signals and allows to reject unsuitable samples. The damage ratios can also be plotted in maps for damage screening and for selecting optimal spots for measurements. Key Points: Annealing and inhomogeneous damage are two main factors hindering radiation‐damage estimation for zircon Raman datingComparison of internal and external Raman bandwidths allows to detect partial annealing of radiation damage in zirconComparison of internal Raman bandwidths allows to detect artifactual broadening in zoned zircon [ABSTRACT FROM AUTHOR]

We measured the fully resolved 3-dimensional velocity distributions of nitric oxide photodesorbed from a gold single crystal. These experiments combine time-of-flight measurements and the velocity map imaging technique to yield velocity distributions resolved in three dimensions for a prototypical surface-adsorbate system. Nitric oxide adsorbed on Au(100) was photodesorbed using a 355 nm laser beam. The desorbed NO molecules were ionised in the gas-phase by resonance-enhanced multi-photon ionisation within a set of velocity map imaging optics. The NO molecules preferentially leave the surface along the surface normal with a very narrow angular distribution, indicating a non-thermal desorption process. [ABSTRACT FROM AUTHOR]

The adsorption and photosorption properties of aerosol particles from zircon (ZrSiO4) have been studied under conditions similar to tropospheric. The physicochemical characteristics of the aerosol were determined by diffuse reflection spectroscopy. The composition of the adsorbed layer formed in the troposphere is analyzed. The kinetic dependences of CO2 desorption and O2 adsorption in the dark and under illumination are studied. The quantum yields and spectral dependences of the quantum yields of photodesorption and photoadsorption are determined. [ABSTRACT FROM AUTHOR]

The microstructural evolution of a Zr-Al-Cu-Ni metallic glass induced by irradiation with Ar ions was investigated. Under ion irradiation, the Cu- and Ni-enriched nanostructures (diameter of 30-50 nm) consisted of crystalline and amorphous structures were formed. Further, Cu- and Ni-depleted nanostructures with diameters of 5-20 nm were also observed. The formation of these nanostructures can be ascribed to the migration of Cu and Ni atoms in the irradiated metallic glass. [ABSTRACT FROM AUTHOR]

We present here the first evidence of photodesorption induced by low-intensity non-resonant light from an yttrium thin foil, which works as a neutralizer for Rb and Fr ions beam. Neutral atoms are suddenly ejected from the metal surface in a pulsed regime upon illumination with a broadband flash light and then released in the free volume of a pyrex cells. Here atoms are captured by a Magneto-Optical Trap (MOT), which is effectively loaded by the photodesorption. Loading times of the order of the flash rise time are measured. Desorption is also obtained in the continuous regime, by exploiting CW visible illumination of the metallic neutralizer surface. We demonstrate that at lower CW light intensities vacuum conditions are not perturbed by the photodesorption and hence the MOT dynamics remains unaffected, while the trap population increases thanks to the incoming desorbed atoms flux. Even with the Y foil at room temperature and hence with no trapped atoms, upon visible illumination, the number of trapped atoms reaches 105. The experimental data are then analyzed by means of an analytical rate equation model, which allows the analysis of this phenomenon and its dynamics and allows the determination of critical experimental parameters and the test of the procedure in the framework of radioactive Francium trapping. In this view, together with an extensive investigation of the phenomenon with 85Rb, the first demonstration of the photodesorption-aided loading of a 210Fr MOT is shown. [ABSTRACT FROM AUTHOR]

The photodesorption of CO from TiO2(110) by femtosecond pulses is investigated with the Surrogate Hamiltonian approach. The aim of the study is to resolve the relaxation mechanism and forecast the lifetime of the exited state based on a microscopic description of the excitation and relaxation processes. The parameters characterizing the system are obtained from ab initio and Density Functional Theory-calculations with one parameter estimated from physical considerations and convergence studies. Two electronic states are considered and the relaxation is assumed to be due to the interaction of the excited adsorbate with electron hole pairs in the surface. Desorption probabilities and velocity distributions of the desorbing molecules are calculated and an exited state lifetime is predicted. Throughout this paper atomic units, i.e., ℏ = me = e = a0 = 1, have been used unless otherwise stated. [ABSTRACT FROM AUTHOR]

A three-channel model of interaction of the O2 gas with zinc oxide during photoactivated oxygen isotope exchange (POIE) in a flow-through reactor is suggested including (1) photoadsorption, (2) exchange in the gas phase (homo-exchange), and (3) zinc oxide–gas exchange (hetero-exchange). In contrast to previous methods, the model includes photoadsorption as an increase in the rate of mixture renewal, which eliminates possible distortions of the time dependences of the calculated rates. Derivation of formulas and experimental data processing are given for POIE in the O2–ZnO system used as an example, under illumination in interband and exciton absorption regions and in the region of absorption by defects in the structure of ZnO. [ABSTRACT FROM AUTHOR]

The extreme sensitivity of 2D-layered materials to environmental adsorbates, which is typically seen as a challenge, is harnessed in this study to fine-tune the material properties. This work investigates the impact of environmental adsorbates on electrical properties by studying metal-semiconductor-metal (MSM) devices fabricated on CVD-synthesized SnSe flakes. The freshly prepared devices exhibit positive photoconductivity (PPC), whereas they gradually develop negative photoconductivity (NPC) after being exposed to an ambient environment for ∼1 day. While the photodetectors based on positive photoconductivity exhibit a responsivity and detectivity of 6.1 A/W and 5.06 × 10 8 Jones, the same for the negative photoconductivity-based photodetector reaches up to 36.3 A/W and 1.49 × 10 9 Jones, respectively. In addition, the noise-equivalent power of the NPC photodetector decreases by 300 times as compared to the PPC device, which implies a prominent detection capability of the NPC device against weak photo signals. To substantiate the hypothesis that negative photoconductivity stems from the photodesorption of water and oxygen molecules on the dangling bonds of SnSe flakes, the flakes are etched along the most active planes (010) with a focused laser beam in an inert environment, which enhances responsivity by 43%, supporting negative photoconductivity linked to photodesorption. Furthermore, the humidity-dependent dark current variation of the NPC photodetectors is used to design a humidity sensor for human respiration monitoring with faster response and recovery times of 0.72 and 0.68 s, respectively. These findings open up the possibility of tuning the photoelectrical response of layered materials in a facile manner to develop future sensors and optoelectronic multifunctional devices.

In the framework of the large hadron collider (LHC) upgrade project, new materials are proposed for the vacuum. Amorphous carbon deposited onto the vacuum-chamber wall is examined as a coating with a low secondary electron emission rate for superconducting systems designed to upgrade the LHC, i.e., to increase the luminosity of the machine (HL-LHC). Since protons will generate synchrotron radiation with a critical energy of ~10 eV and a flux of 1016 photon m–1 s–1, it is important to study the effect of photons on a surface covered with amorphous carbon at room and cryogenic temperatures. The construction and parameters of the setup on the new synchrotron beamline of the VEPP-2000 booster are described. The first results of measuring the photodesorption coefficient are also presented. [ABSTRACT FROM AUTHOR]

Semiconductor fi lms of Cadmium telluride are frequently used for the production of gas sensors. The mechanism of such sensors is based on the change in conductivity caused by gas adsorption and desorption. However, the instability of the surface and its susceptibility to the environment may result in the instability of gas sensors. Therefore, the aim of this paper is to study the effect of light on the conductivity and on adsorption and desorption processes on the surface of CdTe:Sb thin fi lms. Samples of CdTe:Sb solid solutions were synthesized by sintering CdTe and Sb2Te3 composites of exact composition in vacuumed quartz ampoules. The samples were then deposited on glass substrates using vacuum thermal evaporation (~ 1.3·10–3 Pa) in a VUP-5 unit. The thickness of the fi lms was 1 μm. The samples were then tempered in a vacuumed quartz ampoule at 750 оС for 100 hours. The broadband photo-dielectric spectroscopy method was used in the experiments. In order to prevent electrode effects, alternating current measurements were performed. The electrode voltage was 1 V, and the current frequency was 1 Hz. All the measurements were performed at 20 оС, stabilised by a nitrogen fl ow. The study of the effect of light on the conductivity of СdTe:Sb thin fi lms demonstrated that the change in productivity is determined by the quantum energy. The conductivity changes include two stages: a sharp increase at the initial stage and a subsequent decline. Exposure to light E < Eg, results in increased conductivity. The paper shows that the observed reduction in conductivity is caused by photodesorption of oxygen and/or water molecules from the surface of the sample. To interpret the obtained results, a two-layer conductivity model was used in the form of a chain with “parallel” connection between surface and volume conductivities. The nature of surface conductivity, as well as the effect of the frequency of the external alternating fi eld on the results obtained, are to be detailed in our next paper.

Abstract V-4Cr-4Ti alloy for future fusion reactors has attracted great interest. In the present study, twins are observed in the V-4Cr-4Ti alloy irradiated with a 500-keV iron ion beam for 2.67 h at 500 °C. The twins are identified as {112} 〈111〉 type. There is no evident composition distinction between the twins and the matrix. Additionally, dense irradiation-induced dislocation loops are observed. It is proposed that coalescence of dislocation loops can facilitate the growth of stacking faults at which the twins nucleate. The mechanism indicates that twinning might be used to absorb irradiation-induced point defects. Graphical abstract Unlabelled Image [ABSTRACT FROM AUTHOR]

Highlights • Laboratory studies of the photoreactivity (λ > 300 nm) of C2H2 ice accreted on Titan's tholins are presented. • Results show that UV absorption of tholins drives the photoreactivity of C2H2. • In addition to photochemistry, photodesorption is found to be an important process. • We obtained a photodesorption rate of (2.1 ± 0.2) × 10–6 molecule.photon-1 for C2H2 at 355 nm. Abstract Volatile organic molecules formed by photochemistry in the upper atmosphere of Titan can undergo condensation as pure ices in the stratosphere and the troposphere as well as condense as ice layers onto the organic aerosols that are visible as the haze layers of Titan. As solar photons penetrate through Titan's atmosphere, shorter-wavelength photons are attenuated and longer-wavelength photons make it into the lower altitudes, where aerosols become abundant. We conducted an experimental study to evaluate the long wavelength (λ > 300 nm) photoreactivity of these ices accreted on the Titan aerosol-analogs (also known as tholins) made in the laboratory. We have focused on acetylene, the third most abundant hydrocarbon in Titan's atmosphere (after CH 4 and C 2 H 6). Further, acetylene is the most abundant unsaturated hydrocarbon in Titan's atmosphere. Our results indicate that the aerosols can act as activation centers to drive the photoreactivity of acetylene with the aerosols at the accretion interface at wavelengths where acetylene-ice alone does not show photoreactivity. We found that along with photochemistry, photodesorption plays an important role. We observed that about 15% of the initial acetylene is photodesorbed, with a photodesorption rate of (2.1 ± 0.2) × 10−6 molecules•photon−1 at 355 nm. This photodesorption is wavelength-dependent, confirming that it is mediated by the UV absorption of the aerosol analogues, similar to photochemistry. We conclude that the UV–Vis properties of aerosols would determine how they evolve further in Titan's atmosphere and on the surface through photochemical alterations involving longer-wavelength photons. Stronger extinction coefficients in the longer wavelength UV–Vis regions (> 300 nm) of the aerosol give higher efficiencies of photodesorption of accreted volatiles as well as photochemical incorporation of unsaturated condensates (such as acetylene) into the aerosols. [ABSTRACT FROM AUTHOR]

SuperKEKB is an electron–positron collider with asymmetric energies at KEK aiming at a high luminosity of 8.0 × 1035 cm–2 s–1. The main ring (MR) consists of two rings: a 4 GeV positron ring (low-energy ring, LER) and a 7 GeV electron ring (high-energy ring, HER). During the Phase-1 commissioning of the MR from February to June 2016 and the Phase-2 commissioning from March to July 2018, the vacuum system worked well overall. By the end of Phase-2, the total beam doses (integrated beam currents) were 1113 and 1002 Ah, and the maximum beam currents were approximately 1010 and 870 mA for the LER and HER, respectively. The increase in pressure per unit beam current decreased steadily. The photodesorption coefficients reached approximately 1 × 10−6 and 7 × 10−8 molecules photon−1 with photon doses of 5.88 × 1024 and 9.27 × 1024 photons m−1 for the LER and HER, respectively. The beam lifetime was limited by the Touschek effect in both rings. Various new vacuum components, including those installed after the Phase-1 commissioning, such as the beam pipes for the Belle II particle detector, beam collimators, and so on, have been functioning well so far. The electron cloud effect was observed in the LER during Phase-1, but it was suppressed by additional countermeasures applied before Phase-2. Regarding the pressure bursts accompanied with beam losses, which were frequently observed during Phase-1, the frequency of the pressure bursts drastically decreased during Phase-2, but the longer operation time with lower beam currents during Phase-2 than Phase-1 should be taken into account. Several new problems, such as the heating of stainless-steel beam pipes due to the synchrotron radiation emitted from the final focusing quadrupole magnets at the collision point, were found during Phase-2, and countermeasures are being prepared for the Phase-3 commissioning, which will commence in March 2019. SuperKEKB has been accumulating various data and information that will facilitate the design and operation of the vacuum systems in future high-current accelerators. [ABSTRACT FROM AUTHOR]

Kinetics of dehydration of unirradiated and γ-ray irradiated neodymium (III) acetate hydrate with 103 kGy total γ-ray dose absorbed in air atmosphere were studied by isoconversional nonisothermal method. The dehydration proceeds in two steps with the elimination of 0.8 and 0.4 mol of H2O, respectively. This result indicates that the investigated neodymium (III) acetate hydrate contains 1.2 mol of crystalline water in its structure. The dehydration reactions are best described by nucleation (A2 model) and gas diffusion (D4 model) for unirradiated and γ-ray irradiated samples, respectively. Analysis of the kinetic data using linear and nonlinear isoconversional methods showed that the apparent activation energy, Ea (kJ/mol) is dependent on the conversion degree, α, of the dehydration process. The Ea−α plots for both unirradiated and γ-ray irradiated neodymium (III) acetate hydrate showed that the dehydration is a complex process and contains multistep reactions. The results showed that γ-ray irradiation has a significant effect on the kinetics and thermodynamic parameters of the dehydration reaction. Powder X-ray diffraction showed that neodymium (III) acetate hydrate has a monoclinic system (SG P2/m) and no phase transformation was detected by γ-ray irradiation up to 103 kGy absorbed dose. The system maintains the same crystal structure before and after dehydration. [ABSTRACT FROM AUTHOR]

Abstract Superhydrophobic substrate is applied in matrix-assisted laser desorption/ionization mass spectrometry (MALDI MS) detection due to its confinement effect. The weak interaction of superhydrophobic surface with water/salts makes it potential in one-step enrichment and desalting of peptide in MALDI MS analysis. We fabricate a superhydrophobic substrate by spin-coating poly(dimethyl siloxane) (PDMS) on a candle soot layer. On this substrate, the peptide analytes can be confined and enriched in a small area due to the confinement effect and its strong hydrophobic interactions with PDMS. Meanwhile, the desalting can be easily realized by removing the residual solution after the absorption of analyst molecules due to the weak interaction between water/salt contaminants and the superhydrophobic surface. Using this substrate, angiotensin III (Ang III) in the presence of salt with high concentration (2 M or saturated) can be analyzed, and the peptide sequence coverage of 10 μg/mL myoglobin (MYO) and bovine serum albumin (BSA) digests is enhanced to 51% and 26%, which is 37% and 21% analyzed with the commercial ZipTipC 18 pipette tips. The LOD of bacitracin A (Bac A) in milk with this substrate is 100 pM and nearly 360 times lower than the LOD of standard testing method. This substrate has potential practical applications in proteomics research and actual sample analysis. Graphical abstract fx1 Highlights • A superhydrophobic substrate was produced by spin-coating PDMS on a candle soot layer. • Enrichment and desalting of peptide was simultaneously realized with the superhydrophobic substrate in MALDI-MS detection. • The superhydrophobic substrate is applicable for detecting practical samples. • The superhydrophobic substrate shows better performance than the commercial ZipTipC 18 pipette tips. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Photodesorption of CO from Si(1 0 0) leads to two non-thermal desorption channels. • The channels with the higher translation energy has the extra energy of one vibrational quantum. • Both channels originate from a single adspecies. • The dynamics is only little influenced by the excitation energy in the range from 3.5 to 4.3 eV. Abstract The photodesorption of CO from Si(1 0 0) has been studied using 355 and 266 nm light obtaining time-of-flight spectra detailing the translation energy released. The spectra clearly exhibit two non-thermal desorption channels, of which one is characterized by an offset energy the size of which is remarkably close to the vibrational quantum of CO. Detailed studies of the spectra as function of coverage and laser fluence used prove that both desorption channels originate from a single adsorbed species. It is suggested that the energy offset is due to vibrational to translational energy transfer along the reaction pathway of the desorbing molecule. [ABSTRACT FROM AUTHOR]

The authors show that the desorption rate of two model molecules, indole and benzoic acid, from thin films of indium tin oxide nanocrystals supporting near- and mid-infrared (0.33–0.48 eV) localized surface plasmon resonances (LSPRs) is enhanced by as much as 60% upon illumination with broadband infrared light. The desorption rate increases linearly with light intensity. No increase in the desorption rate is detected for undoped In2O3 nanocrystal thin films or when photons resonant with the LSPR are blocked. The authors study the desorption rate enhancement as a function of illumination intensity, LSPR energy, and isotopic substitution. Importantly, the authors demonstrate the accelerated desorption via in-coupling of light to LSPRs with energies well within the mid-infrared. Their work opens the door to using these low energy photons as choreographers of chemical processes and sets the stage for future mechanistic studies. [ABSTRACT FROM AUTHOR]

Aims. This paper investigates how the far-IR water ice features can be used to infer properties of disks around T Tauri stars and the water ice thermal history. We explore the power of future observations with SOFIA/HIRMES and SPICA's proposed far-IR instrument SAFARI. Methods. A series of detailed radiative transfer disk models around a representative T Tauri star are used to investigate how the far-IR water ice features at 45 and 63 μm change with key disk properties: disk size, grain sizes, disk dust mass, dust settling, and ice thickness. In addition, a series of models is devised to calculate the water ice emission features from warmup, direct deposit, and cooldown scenarios of the water ice in disks. Results. Photodesorption from icy grains in disk surfaces weakens the mid-IR water ice features by factors of 4–5. The far-IR water ice emission features originate from small grains at the surface snow line in disks at distance of 10–100 au. Unless this reservoir is missing in disks (e.g., transitional disks with large cavities), the feature strength does not change. Grains larger than 10 μm do not contribute to the features. Grain settling (using turbulent description) affects the strength of the ice features by at most 15%. The strength of the ice feature scales with the disk dust mass and water ice fraction on the grains, but saturates for dust masses higher than 10−4M⊙ and for ice mantles that increase the dust mass by more than 50%. The various thermal histories of water ice leave an imprint on the shape of the features (crystalline and/or amorphous) and on the peak strength and position of the 45 μm feature. SOFIA/HIRMES can only detect crystalline ice features that are much stronger than those simulated in our standard T Tauri disk model in deep exposures (1 h). SPICA/SAFARI can detect the typical ice features in our standard T Tauri disk model in short exposures (10 min). Conclusions. The sensitivity of SPICA/SAFARI will allow the detailed study of the 45 and 63 μm water ice feature in unbiased surveys of T Tauri stars in nearby star forming regions and an estimate of the mass of their ice reservoir. The water ice emission features carry an imprint of the thermal history of the ice, and thus can distinguish between various formation and transport scenarios. Amorphous ice at 45 μm that has a much broader and flatter peak could be detected in deep surveys if the underlying continuum can be well characterized and the baseline stability of SAFARI is better than a few percent. [ABSTRACT FROM AUTHOR]

In this study, the CO2 adsorption properties of different metal mixed oxides (MMO) obtained by calcination of different layered double hydroxides (LDH) are addressed. Four types of LDH, with composition M1-x2+Mx3+OH2x+·[Ax/nn-·mH2O]x-, where M2+=Zn, Cu, Ni, M3+=Al, x = 0.33, n = 2 and A = CO32−, were studied by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy and thermogravimetric analysis coupled with mass spectrometry (TG-MS). Different thermal behaviors upon heating were observed depending on the LDH composition, resulting in the exploitation of different calcination temperatures to convert LDH into mixed metal oxides (MMO). MMO were exposed to ambient air or pure carbon dioxide atmosphere to evaluate CO2 adsorption properties. Aging in ambient condition leads to adsorption of both CO2 and water, from ambient moisture, with variable ratios depending on the MMO composition. Furthermore, all the MMO were demonstrated to be able to adsorb CO2 in pure gas stream, in the absence of moisture. In both ambient and pure CO2 conditions, the performance of MMO is strongly dependent on the metal composition of MMO. In particular, the presence of Cu in the structure turned out to be beneficial in terms of adsorption capacity, with a maximum mass gain for CuAl MMO of 4 and 15% in pure CO2 and in atmospheric conditions, respectively. [ABSTRACT FROM AUTHOR]

The mechanism of the effect of adsorbed oxygen on photoluminescence (PL) of ZnO powders and ZnO/Si ALD films in the UV–VIS regions was studied, simultaneously with the in-situ UV photoelectron spectroscopy (UPS) and mass spectrometry (MS) measurements. We have found a drastic (up to 10 times) increase of the exciton PL along with a slight (by ~ 1.5 times) increase of green PL induced by thermo-reducing of ZnO surface in H 2 or CO atmosphere or by a UV–VIS photo-reducing in the vacuum. The reaction products H 2 O, CO 2 and photo-desorbed O 2 were registered by the MS. According to UPS (8.43 eV), the change in PL is accompanied by a significant change in the surface dipole value δ without shift of the Fermi level E F or of the band bending V S . We believe that the slow surface states interact with the adsorbed oxygen and thus create a surface 2D-quantum well whose internal field destroys the excitons. The internal fast surface states not interacting with the slow ones provide a pinning of the Fermi level and the stability of the band bending value. The adsorbed oxygen also affects the surface defects thus reducing the VIS luminescence of ZnO. [ABSTRACT FROM AUTHOR]

The photodesorption of icy grain mantles has been claimed to be responsible for the abundance of gas-phase molecules towards cold regions. Being water a ubiquitous molecule, it is crucial to understand its role in photochemistry and its behaviour under an ultraviolet field. We report new measurements on the ultraviolet (UV) photodesorption of water ice and its H2, OH, and O2 photoproducts using a calibrated quadrupole mass spectrometer. Solid water was deposited under ultra-high-vacuum conditions and then UV-irradiated at various temperatures starting from 8K with a microwave discharged hydrogen lamp. Deuterated water was used for confirmation of the results. We found a photodesorption yield of 1.3 × 10-3 molecules per incident photon for water and 0.7 × 10-3 molecules per incident photon for deuterated water at the lowest irradiation temperature, 8 K. The photodesorption yield per absorbed photon is given and comparison with astrophysical scenarios, where water ice photodesorption could account for the presence of gas-phase water towards cold regions in the absence of a thermal desorption process, is addressed. [ABSTRACT FROM AUTHOR]

The analysis of nonplanar samples in ambient mass spectrometry poses a formidable challenge. Here, an ion source equipped with laser triangulation for analyzing nonplanar surfaces was constructed. It was designed as a two-position device, where the sample height was measured using laser triangulation and the target compounds were then analyzed. Thanks to a stage movable in xyz, the ion source maintained an optimal vertical distance between the sample and the sampling capillary for each measured spot during the surface analysis. The xyz-coordinates for the movement of the sample stage were computed using the laser sensor data in such a way as to avoid direct contact of the sampling capillary and the measured surface. The ion source performance and its ability to analyze various morphologies were tested using desorption electrospray ionization with plastic objects coated by 2,5-dimethoxybenzoic acid. The experiments showed excellent performance for nonplanar samples but also revealed some limitations especially on object edges and steep slopes. The applicability of the ion source operated in desorption electrospray ionization and desorption atmospheric pressure photoionization was examined for food and pharmaceutical samples. Chemicals on the surface of nonplanar samples were probed along a line extending across the surface of the measured objects. The device provided high-quality spectra, regardless of the sample height at the measured spot. The automatic adjustments of the sample stage in xyz proved to be beneficial for analyzing nonplanar samples and for simultaneous measurement of samples with various dimensions and shapes. [ABSTRACT FROM AUTHOR]

Photodesorption of rubidium atoms from crystalline sapphire surface is experimentally studied using the time-of-flight method and the total internal reflection effect. The adsorption energy of rubidium atoms on sapphire is determined to be ~0.7 eV. The dependence of the kinetic energy of desorbed rubidium atoms on the desorbing photon energy in the sapphire transparency range and in the absorption band of rubidium adatoms is determined. It is found that the average kinetic energy of outgoing atoms decreases at desorbing photon energies exceeding 2.3 eV. A model is proposed that relates the decrease in the kinetic energy of desorbed atoms to the appearance of a new channel of desorption of atoms in an excited electronic state. [ABSTRACT FROM AUTHOR]

Context. The gas and dust in circumstellar disks provide the raw materials to form planets. The study of organic molecules and their building blocks in such disks offers insight into the origin of the prebiotic environment of terrestrial planets. Aims: We aim to determine the distribution of formaldehyde, H2CO, in the disk around HD 163296 to assess the contribution of gas- and solid-phase formation routes of this simple organic. Methods: Three formaldehyde lines were observed (H2CO 303-202, H2CO 322-221, and H2CO 321-220) in the protoplanetary disk around the Herbig Ae star HD 163296 with ALMA at 0.5" (60 AU) spatial resolution. Different parameterizations of the H2CO abundance were compared to the observed visibilities, using either a characteristic temperature, a characteristic radius or a radial power law index to describe the H2CO chemistry. Similar models were applied to ALMA Science Verification data of C18O. In each scenario, χ2 minimization on the visibilities was used to determine the best-fit model in each scenario. Results: H2CO 303-202 was readily detected via imaging, while the weaker H2CO 322-221 and H2CO 321-220 lines required matched filter analysis to detect. H2CO is present throughout most of the gaseous disk, extending out to 550 AU. An apparent 50 AU inner radius of the H2CO emission is likely caused by an optically thick dust continuum. The H2CO radial intensity profile shows a peak at 100 AU and a secondary bump at 300 AU, suggesting increased production in the outer disk. In all modeling scenarios, fits to the H2CO data show an increased abundance in the outer disk. The overall best-fit H2CO model shows a factor of two enhancement beyond a radius of 270 ± 20 AU, with an inner abundance (relative to H2) of 2 - 5 × 10-12. The H2CO emitting region has a lower limit on the kinetic temperature of T> 20 K. The C18O modeling suggests an order of magnitude depletion of C18O in the outer disk and an abundance of 4 - 12 × 10-8 in the inner disk. Conclusions: There is a desorption front seen in the H2CO emission that roughly coincides with the outer edge of the 1.3 millimeter continuum. The increase in H2CO outer disk emission could be a result of hydrogenation of CO ices on dust grains that are then sublimated via thermal desorption or UV photodesorption. Alternatively, there could be more efficient gas-phase production of H2CO beyond 300 AU if CO is photodisocciated in this region. [ABSTRACT FROM AUTHOR]

Structural changes in water layers on a CO-covered Pt electrode triggered by rapid pulsed laser heating of the interface are studied using potential transient measurements. When the laser energy density is below 20 mJ cm − 2 , the water layers undergo a change in orientation, which causes a negative shift in the rest potential that recovers within 20 μs with the cooling of the interface. In contrast, when the laser intensity exceeds 20 mJ cm − 2 , the CO is desorbed and the rest potential first experiences a positive shift, which is followed by a negative shift. This positive shift is caused by replacement of the CO by water and subsequent restructuring of the water layer. The restructuring rate depends strongly on the electrolyte cation: the rest potential reaches a maximum value within ~ 100 μs for hydrophilic cations such as H + and Li + , whereas it takes > 10 ms for hydrophobic cations such as Et 4 N + and Bu 4 N + . Surface-enhanced IR absorption measurements suggest that the water molecules around the hydrophobic cations are more strongly hydrogen-bonded than those around the hydrophilic cations. Because the restructuring involves a reforming of the hydrogen-bonding network at the electric double layer, Et 4 N + and Bu 4 N + , which have more strongly hydrogen-bonded hydration shells, require more time than H + and Li + . [ABSTRACT FROM AUTHOR]

This paper describes the generation of 39 Ar, via reactor irradiation of potassium carbonate, followed by quantitative analysis (length-compensated proportional counting) to yield two calibration standards that are respectively 50 and 3 times atmospheric background levels. Measurements were performed in Pacific Northwest National Laboratory's shallow underground counting laboratory studying the effect of gas density on beta-transport; these results are compared with simulation. The total expanded uncertainty of the specific activity for the ~50× 39 Ar in P10 standard is 3.6% (k=2). [ABSTRACT FROM AUTHOR]

Two of the popular refrigeration cycles, VC (Vapor Compression), and VA (Vapor Absorption) are used extensively for refrigeration purposes. In this paper, a system is proposed that works using both cycles powered by an IC (Internal Combustion) engine, where mechanical energy is used to run the VC cycle while exhaust gasses are used to operate the VA cycle. The VC cycle works on R12 refrigerant while LiBr-H2O combination is selected for operation of VA cycle. Firstly, the refrigeration system is modeled, followed by a parametric study to investigate the impacts of various operating parameters on the system performance. The results exhibit that for maximum chilling and overall performance, the condenser and evaporator pressures in the VC cycle are obtained as 710 and 340 kPa, respectively, whereas generator and absorber temperatures in VA cycle are 85 and 20°C, respectively. [ABSTRACT FROM AUTHOR]

In this study, a room-temperature acetone gas sensor based on monolayer graphene is proposed with the improvement by ultraviolet (UV) illumination. The monolayer graphene film was grown by low pressure chemical vapor deposition and then transferred to the interdigital gold electrode by the standard transferred method. To test the acetone sensing properties, the concentration of 300, 600 and 900 ppb acetone provided by a gas standards generator is applied in the testing chamber. The resistance changes following a doping type modification of graphene between illumination and acetone gas. A 1.9% change in short time illumination on graphene could be obtained at 600 ppb and room temperature, which could make this a candidate for biomedical application in the future. In the meantime, a mechanism is proposed to explain whole behavior based on photo-induced molecular desorption. [ABSTRACT FROM AUTHOR]

The Large Hadron Collider (LHC), currently under operation at CERN, is colliding intense proton beams at the highest energy frontier up to ∼14 TeV in the centre of mass. This superconducting storage ring is at the origin of the discovery in 2012 of the so-called ‘Higgs’ Boson explaining the origin of the mass of weak bosons W + ,W − and Z also discovered at CERN in 1983. The arc vacuum system, which operates at cryogenic temperatures, consists of a 1.9 K cold bore which houses a 5–20 K beam screen. Beam collisions are performed inside a Non-Evaporable-Getter coated vacuum system located in long straight sections held at room temperature. These vacuum systems were designed to be stable under ion bombardment, to cope with intense VUV synchrotron radiation flux and to mitigate beam induced multipacting effects. In this paper, the LHC beam vacuum system design is recalled. Its operation, challenges and achieved performances during the commissioning phase will be discussed in detail. [ABSTRACT FROM AUTHOR]

Organic coatings have been widely used in atomic physics during the last 50 years because of their mechanical properties, allowing preservation of atomic spins after collisions. Nevertheless, this did not produce detailed insight into the characteristics of the coatings and their dynamical interaction with atomic vapors. This has changed since the 1990s, when their adsorption and desorption properties triggered a renewed interest in organic coatings. In particular, a novel class of phenomena produced by non-destructive light-induced desorption of atoms embedded in the coating surface was observed and later applied in different fields. Nowadays, low energy non-resonant atomic photodesorption from organic coatings can be considered an almost standard technique whenever large densities of atomic vapors or fast modulation of their concentration are required. In this paper, we review the steps that led to this widespread diffusion, from the preliminary observations to some of the most recent applications in fundamental and applied physics. [ABSTRACT FROM AUTHOR]

Purpose: In pediatric cancer survivors treated with whole-brain irradiation (WBI), long-term cognitive deficits and morbidity develop that are poorly understood and for which there is no treatment. We describe similar cognitive defects in juvenile WBI rats and correlate them with alterations in diffusion tensor imaging and magnetic resonance spectroscopy (MRS) during brain development.Methods and Materials: Juvenile Fischer rats received clinically relevant fractionated doses of WBI or a high-dose exposure. Diffusion tensor imaging and MRS were performed at the time of WBI and during the subacute (3-month) and late (6-month) phases, before behavioral testing.Results: Fractional anisotropy in the splenium of the corpus callosum increased steadily over the study period, reflecting brain development. WBI did not alter the subacute response, but thereafter there was no further increase in fractional anisotropy, especially in the high-dose group. Similarly, the ratios of various MRS metabolites to creatine increased over the study period, and in general, the most significant changes after WBI were during the late phase and with the higher dose. The most dramatic changes observed were in glutamine-creatine ratios that failed to increase normally between 3 and 6 months after either radiation dose. WBI did not affect the ambulatory response to novel open field testing in the subacute phase, but locomotor habituation was impaired and anxiety-like behaviors increased. As for cognitive measures, the most dramatic impairments were in novel object recognition late after either dose of WBI.Conclusions: The developing brains of juvenile rats given clinically relevant fractionated doses of WBI show few abnormalities in the subacute phase but marked late cognitive alterations that may be linked with perturbed MRS signals measured in the corpus callosum. This pathomimetic phenotype of clinically relevant cranial irradiation effects may be useful for modeling, mechanistic evaluations, and testing of mitigation approaches. [ABSTRACT FROM AUTHOR]

Using temperature programmed desorption (TPD) and photon-stimulated desorption (PSD), we show that coadsorbates of varying binding energies on the rutile TiO 2 (110) surface exert a commensurate inhibiting influence on the hole-mediated photodesorption of adsorbed O 2 . A variety of coadsorbates (Ar, Kr, Xe, N 2 , CO, CO 2 , CH 4 , N 2 O, acetone, methanol or water) were shown to quench O 2 photoactivity, with the extent correlating with the coadsorbate's gas phase basicity, which in turn determines the strength of the coadsorbate–Ti 4 + bond. Coadsorbed rare gases inhibited the photodesorption of O 2 by ~ 10–25%, whereas strongly bound species (water, methanol, and acetone) nearly completely inhibited O 2 PSD. We suggest that coadsorption of these molecules inhibit the arrival probability of holes to the surface. Band-bending effects, which vary with the extent of charge transfer between the coadsorbate and the TiO 2 (110) surface, are not expected to be significant in the cases of the rare gases and physisorbed species. These results indicate that neutral coadsorbates can exert a significant influence on charge transfer events by altering the interfacial dipole in the vicinity of the target molecule. [ABSTRACT FROM AUTHOR]

In this paper, we developed a simple method to fabricate an indium-doped ZnO nanostructure ultraviolet (UV) photodetector (PD) on a glass substrate. Through the aqueous chemical solution method, the indium-doped ZnO nanostructure uniformly grew on a glass substrate. The average length and diameter were 3.06 \mu \textm and 38 nm, respectively. At 1 V bias, the photo-to-dark current ratio of the indium-doped ZnO PD was 740 under UV light irradiation (365 nm). The sample exhibited fast response and recovery time. The increase and decrease times were 3.02 and 1.53 s, correspondingly. When irradiated at 360 nm, the UV-visible rejection ratio of the indium-doped ZnO nanostructure PD was approximately 312. The indium-doped ZnO nanostructure PD exhibited high sensitivity, fast response and recovery times, and good orientation properties. [ABSTRACT FROM PUBLISHER]

The coordination of H2 to a metal center via polarization of its σ bond electron density, known as a Kubas complex, is the means by which H2 chemisorbs at Ru4+ sites on the rutile RuO2(110) surface. This distortion of electron density off an interatomic axis is often described as a 'banana-bond.' We show that the Ru-H2 banana-bond can be destabilized and split using visible light. Photodesorption of H2 (or D2) is evident by mass spectrometry and scanning tunneling microscopy. From time-dependent density functional theory, the key optical excitation splitting the Ru-H2 complex involves an interband transition in RuO2 which effectively diminishes its Lewis acidity, thereby weakening the Kubas complex. Such excitations are not expected to affect adsorbates on RuO2 given its metallic properties. Therefore, this common thermal cocatalyst employed in photocatalysis is, itself, photoactive. [ABSTRACT FROM AUTHOR]

This work presents a strategy of nitrogen anion doping to suppress negative gate-bias illumination instability. The electrical performance and negative gate-bias illumination stability of the ZnSnON thin film transistors (TFTs) are investigated. Compared with ZnSnO-TFT, ZnSnON-TFT has a 53% decrease in the threshold voltage shift under negative bias illumination stress and electrical performance also progresses obviously. The stability improvement of ZnSnON-TFT is attributed to the reduction in ionized oxygen vacancy defects and the photodesorption of oxygen-related molecules. It suggests that anion doping can provide an effective solution to the adverse tradeoff between field effect mobility and negative bias illumination stability. [ABSTRACT FROM AUTHOR]

We simulate the femtosecond-laser-induced desorption dynamics of a diatomic molecule from a metal surface by including the effect of the electron and phonon excitations created by the laser pulse. Following previous models, the laser-induced surface excitation is treated through the two temperature model, while the multidimensional dynamics of the molecule is described by a classical Langevin equation, in which the friction and random forces account for the action of the heated electrons. In this work we propose the additional use of the generalized Langevin oscillator model to also include the effect of the energy exchange between the molecule and the heated surface lattice in the desorption dynamics. The model is applied to study the laser-induced desorption of O2 from the Ag(110) surface, making use of a six-dimensional potential energy surface calculated within density functional theory. Our results reveal the importance of the phonon mediated process and show that, depending on the value of the electronic density in the surroundings of the molecule adsorption site, its inclusion can significantly enhance or reduce the desorption probabilities. [ABSTRACT FROM AUTHOR]

Context. Ice mantles that formed on top of dust grains are photoprocessed by the secondary ultraviolet (UV) field in cold and dense molecular clouds. UV photons induce photochemistry and desorption of ice molecules. Experimental simulations dedicated to ice analogs under astrophysically relevant conditions are needed to understand these processes. Aims. We present UV-irradiation experiments of a pure CO2 ice analog. Calibration of the quadrupole mass spectrometer allowed us to quantify the photodesorption of molecules to the gas phase. This information was added to the data provided by the Fourier transform infrared spectrometer on the solid phase to obtain a complete quantitative study of the UV photoprocessing of an ice analog. Methods. Experimental simulations were performed in an ultra-high vacuum chamber. Ice samples were deposited onto an infrared transparent window at 8K and were subsequently irradiated with a microwave-discharged hydrogen flow lamp. After irradiation, ice samples were warmed up until complete sublimation was attained. Results. Photolysis of CO2 molecules initiates a network of photon-induced chemical reactions leading to the formation of CO, CO3, O2, and O3. During irradiation, photon-induced desorption of CO and, to a lesser extent, O2 and CO2 took place through a process called indirect desorption induced by electronic transitions, with maximum photodesorption yields (Ypd) of ∼1.2 × 10-2 molecules incident photon-1, ∼9.3 × 10-4 molecules incident photon-1, and ∼1.1 × 10-4 molecules incident photon-1, respectively. Conclusions. Calibration of mass spectrometers allows a direct quantification of photodesorption yields instead of the indirect values that were obtained from infrared spectra in most previous works. Supplementary information provided by infrared spectroscopy leads to a complete quantification, and therefore a better understanding, of the processes taking place in UV-irradiated ice mantles. [ABSTRACT FROM AUTHOR]

Dye recovery is of great significance for a circular economy and sustainable development. However, green recovery strategies without secondary pollution remain a significant challenge. To resolve this issue, a light-responsive smart material (citric acid-modified BiOCOOH (m-BOCH)) was synthesized and applied for dye recovery through adsorption in the dark, and desorption under visible light. With the modification of citric acid, the adsorption level of methylene blue (MB) on m-BOCH (43.4%) was more than six times that of pure BiOCOOH (7.1%). The desorption rate was ∼90% in 120 min under 420 nm light irradiation (there was no desorption for pure BOCH). Further, the adsorption rate was improved to 83.9% and the desorption rate remained stable at an optimal pH of 10.09. Characterization results indicated that carboxyl groups were modified onto the surface of BiOCOOH and served as adsorption sites for MB. Under visible light exposure, the connections between the carboxyl groups and BiOCOOH were damaged, which led to the desorption of MB from the surface of the m-BOCH. The recovered MB exhibited a good staining effect on hepatic stellate cells (HSC) as a fresh dye. The regeneration of m-BOCH was achieved through a moderate hydrothermal process, and the adsorption and desorption capacities were restored to 80.8% and 85.7%, respectively. This research provides a novel environmentally compatible strategy for dye recovery without secondary pollution. This is a very promising treatment technique for dye effluents, which highlights the application of smart materials resource recycling for environmental remediation. • The citric acid modified BiOCOOH (m-BOCH) was synthesized by a simple hydrothermal method. • The m-BOCH exhibited good adsorption and photo-induced desorption property to MB. • Carboxyl was modified onto the surface of BOCH and acted as adsorption site to MB. • The connection between carboxyl and BOCH was damaged with light and MB released into solution. [ABSTRACT FROM AUTHOR]