Suchergebnisse

We thank the Ministerio de Economia y Competitividad (CTQ2017-85454-C2-1-P and CTQ2017-85454-C2-2-P), Ministerio de Ciencia e Innovacion (PID2020-113059GB-C21 and PID2020-113059GB-C22) and Junta de Andalucia (P20.00162) (Spain) for funding and P.R. and A. O. G. also for FPU contracts. Funding for open access charge is acknowledged to Universidad de Granada / CBUA.We also thank Big&Open Data Innovation Laboratory (BODaI-Lab), University of Brescia, granted by Fondazione Cariplo and Regione Lombardia, for access to resources of Computing Center CINECA (Bologna), Italy. Support from the Italian MIUR (Grant No. 2017A4XRCA) is also acknowledged. ; In this paper, we describe the optical and chiroptical properties of an enantiopure multipodal ortho-oligophenylethynylene (S,S,S,S)-1 presenting four chiral sulfoxide groups at the extremes. The presence of these groups together with alkynes allows the coordination with carbophilic Ag(I), and/or oxophilic Zn(II) cations, yielding double helical structures in an enantiopure way. In this sense, different behaviors in absorption, fluorescence, ECD and CPL spectra have been found depending on the stoichiometry and nature of the metal. We have observed that Zn(II) coordination favors an intensity increase of the electronic circular dichroism (ECD) spectra of compound (S,S,S,S)-1 yielding an M-helicity in the ortho-oligophenylene ethynylene (o-OPE) backbone. On the other hand, ECD spectra of final Ag(I) complex shows two different bands with an opposite sign to the free ligand, thus giving the P-helical isomer. In addition, circularly polarized luminescence (CPL) exhibit an enhanced intensity and negative sign in both complexes. Computational studies were also carried out, supporting the experimental results. ; Spanish Government CTQ2017-85454-C2-1-P CTQ2017-85454-C2-2-P ; Instituto de Salud Carlos III Spanish Government European Commission PID2020-113059GB-C21 PID2020-113059GB-C22 ; Junta de Andalucia European Commission P20.00162 ; University of Brescia / CBUA ; Fondazione Cariplo ; Ministry of Education, Universities and Research (MIUR) 2017A4XRCA ; Regione Lombardia

[EN] Coherent interconversion of signals between optical and mechanical domains is enabled by optomechanical interactions. Extreme light-matter coupling produced by confining light to nanoscale mode volumes can then access single mid-infrared (MIR) photon sensitivity. Here, we used the infrared absorption and Raman activity of molecular vibrations in plasmonic nanocavities to demonstrate frequency upconversion. We converted approximately 10-micrometer-wavelength incoming light to visible light by surface-enhanced Raman scattering (SERS) in doubly resonant antennas that enhanced upconversion by more than 10(10). We showed 140% amplification of the SERS anti-Stokes emission when an MIR pump was tuned to a molecular vibrational frequency, obtaining lowest detectable powers of 1 to 10 microwatts per square micrometer at room temperature. These results have potential for low-cost and large-scale infrared detectors and spectroscopic techniques. ; This work was supported by the European Union's Horizon 2020 Research and Innovation Program under grant agreements 829067 (THOR), 861950 (POSEIDON), and 883703 (PICOFORCE) and by the Engineering and Physical Sciences Research Council (EPSRC) (Cambridge NanoDTC grants EP/L015978/1, EP/L027151/1, EP/S022953/1, EP/P029426/1, and EP/R020965/1). X.Z. acknowledges support from KU Leuven Internal Funds C14/19/083, IDN/20/014, KA/20/019, and FWO G090017N. R.C. acknowledges support from Trinity College, University of Cambridge. Z.K.B. and E.R. acknowledge funding from the EPSRC (EP/R013012/1, EP/L027151/1) and ERC project 757850 BioNet. We are grateful to the UK Materials and Molecular Modelling Hub, which is partially funded by EPSRC (EP/P020194/1), for computational resources. ; Xomalis, A.; Zheng, X.; Chikkaraddy, R.; Koczor-Benda, Z.; Miele, E.; Rosta, E.; Vandenbosch, GAE. (2021). Detecting mid-infrared light by molecular frequency upconversion in dual-wavelength nanoantennas. Science. 374(6572):1268-1271. https://doi.org/10.1126/science.abk2593 ; S ; 1268 ; 1271 ; 374 ; 6572

The quantum-confined Stark effect (QCSE) is an established optical modulation mechanism, yet top-performing modulators harnessing it rely on costly fabrication processes. Here, we present large modulation amplitudes for solution-processed layered hybrid perovskites and a modulation mechanism related to the orientational polarizability of dipolar cations confined within these self-assembled quantum wells. We report an anomalous (blue-shifting) QCSE for layers that contain methylammonium cations, in contrast with cesium-containing layers that show normal (red-shifting) behavior. We attribute the blue-shifts to an extraordinary diminution in the exciton binding energy that arises from an augmented separation of the electron and hole wavefunctions caused by the orientational response of the dipolar cations. The absorption coefficient changes, realized by either the red- or blue-shifts, are the strongest among solution-processed materials at room temperature and are comparable to those exhibited in the highest-performing epitaxial compound semiconductor heterostructures. ; The work presented in this publication was supported by funding from the Natural Sciences and Engineering Research Council (NSERC) of Canada and from an award (KUS-11-009-21) from the King Abdullah University of Science and Technology. Computations were performed on the General Purpose Cluster supercomputer at the SciNet HPC Consortium. SciNet is funded by: the Canada Foundation for Innovation under the auspices of Compute Canada; the Government of Ontario; Ontario Research Fund—Research Excellence; and the University of Toronto. CHESS is supported by the NSF & NIH/NIGMS via NSF award DMR-1332208. Work was also partially funded by Huawei Canada. We thank E. Palmiano, R. Wolowiec, and D. Kopilovic for assistance in the course of study. We also thank R. Sabatini, L. Quan, O. Ouellette, A. Proppe, J. Fan, M. Saidaminov, A. Jain, M. Liu, and Z. Yang for assistance in the lab and for fruitful discussions.

The quantum-confined Stark effect (QCSE) is an established optical modulation mechanism, yet top-performing modulators harnessing it rely on costly fabrication processes. Here, we present large modulation amplitudes for solution-processed layered hybrid perovskites and a modulation mechanism related to the orientational polarizability of dipolar cations confined within these self-assembled quantum wells. We report an anomalous (blue-shifting) QCSE for layers that contain methylammonium cations, in contrast with cesium-containing layers that show normal (red-shifting) behavior. We attribute the blue-shifts to an extraordinary diminution in the exciton binding energy that arises from an augmented separation of the electron and hole wavefunctions caused by the orientational response of the dipolar cations. The absorption coefficient changes, realized by either the red- or blue-shifts, are the strongest among solution-processed materials at room temperature and are comparable to those exhibited in the highest-performing epitaxial compound semiconductor heterostructures. ; The work presented in this publication was supported by funding from the Natural Sciences and Engineering Research Council (NSERC) of Canada and from an award (KUS-11-009-21) from the King Abdullah University of Science and Technology. Computations were performed on the General Purpose Cluster supercomputer at the SciNet HPC Consortium. SciNet is funded by: the Canada Foundation for Innovation under the auspices of Compute Canada; the Government of Ontario; Ontario Research Fund—Research Excellence; and the University of Toronto. CHESS is supported by the NSF & NIH/NIGMS via NSF award DMR-1332208. Work was also partially funded by Huawei Canada. We thank E. Palmiano, R. Wolowiec, and D. Kopilovic for assistance in the course of study. We also thank R. Sabatini, L. Quan, O. Ouellette, A. Proppe, J. Fan, M. Saidaminov, A. Jain, M. Liu, and Z. Yang for assistance in the lab and for fruitful discussions.

The promise of graphene and its derivatives as next generation sensors for real-time detection of toxic heavy metals (HM) requires a clear understanding of behavior of these metals on the graphene surface and response of the graphene to adsorption events. Our calculations herein were focused on the investigation of the interaction between three HMs, namely Cd, Hg and Pb, with graphene quantum dots (GQDs). We determine binding energies and heights of both neutral and charged HM ions on these GQDs. The results show that the adsorption energy of donor-like physisorbed neutral Pb atoms is larger than that of either Cd or Hg. In contrast to the donor-like behavior of elemental HMs, the chemisorbed charged HM species act as typical acceptors. The energy barriers to migration of the neutral adatoms on GQDs are also estimated. In addition, we show how the substitution of a carbon atom by a HM adatom changes the geometric structure of GQDs and hence their electronic and vibrational properties. UV-visible absorption spectra of HM-adsorbed GQDs vary with the size and shape of the GQD. Based on our results, we suggest a route towards the development of a graphene-based sensing platform for the optical detection of toxic HMs. ; Funding Agencies|European Union [696656]; Swedish Research Council (VR) [621-2014-5805]; Angpanneforeningens Forskningsstiftelse [16-541]; Science Foundation Ireland (SFI) under its Starter Investigator Research Grant (SIRG) Programme [15/SIRG/3314]; Swedish Research Council (VR) Marie Sklodowska Curie International Career Grant [2015-00679]; AForsk [14-517]; Swedish Government Strategic Research Areas in Materials Science on Functional Materials at Linkoping University [2009-00971]; Knut and Alice Wallenberg Foundation through the Strong Field Physics and New States of Matter Grant; Ministry of Education and Science of the Russian Federation [14.Y26.31.0005]

Zn-Ir-O (Zn/Ir ≈ 1/1) thin films have been reported to be a potential p-type TCO material. It is, however, unknown whether it is possible to achieve p-type conductivity at low Ir content, and how the type and the magnitude of conductivity are affected by the film structure. To investigate the changes in properties taking place at low and moderate Ir content, this study focuses on the structure, electrical and optical properties of ZnO:Ir films with iridium concentration varying between 0.0 and 16.4 at.%. ZnO:Ir thin films were deposited on glass, Si, and Ti substrates by DC reactive magnetron co-sputtering at room temperature. Low Ir content (up to 5.1 at.%) films contain both a nano-crystalline wurtzite-type ZnO phase and an X-ray amorphous phase. The size of the crystallites is below 10 nm and the lattice parameters a and c are larger than those of pure ZnO crystal. Structural investigation showed that the film's crystallinity declines with the iridium concentration and films become completely amorphous at iridium concentrations between 7.0 and 16.0 at.%. An intense Raman band at approximately 720 cm− 1 appears upon Ir incorporation and can be ascribed to peroxide O22– ions. Measurable electrical conductivity appears together with a complete disappearance of the wurtzite-type ZnO phase. The conduction type undergoes a transition from n- to p-type in the Ir concentration range between 12.4 and 16.4 at.%. Absorption in the visible range increases linearly with the iridium concentration. ; VMTKC project 18, agreement No. 1.2.1.1/16/A/005; Institute of Solid State Physics, University of Latvia as the Center of Excellence has received funding from the European Union's Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under grant agreement No. 739508, project CAMART²

The final publication is available at Springer via http://dx.doi.org/10.1007/s10008-016-3237-0. ; Abstract CuGaSe2 and CuGaS2 polycrystalline thin film absorbers were prepared by one-step electrodeposition from an aqueous electrolyte containing CuCl2, GaCl3 and H2SeO3. The pH of the solution was adjusted to 2.3 by adding HCl and KOH. Annealing improved crystallinity of CuGaSe2 and further annealing in sulphur atmosphere was required to obtain CuGaS2 layers. The morphology, topography, chemical composition and crystal structure of the deposited thin films were analysed by scanning electron microscopy, atomic force microscopy, energy dispersive spectroscopy and X-ray diffraction, respectively. X-Ray diffraction showed that the asdeposited CuGaSe2 film exhibited poor crystallinity, but which improved dramatically when the layers were annealed in forming gas atmosphere for 40 min. Subsequent sulphurization of CuGaSe2 films was performed at 400 °C for 10 min in presence of molecular sulphur and under forming gas atmosphere. The effect of sulphurization was the conversion of CuGaSe2 into CuGaS2. The formation of CuGaS2 thin films was evidenced by the shift observed in the X-ray diffraction pattern and by the blue shift of the optical bandgap. The bandgap of CuGaSe2 was found to be 1.66 eV, while for CuGaS2 it raised up to 2.2 eV. A broad intermediate absorption band associated to Cr and centred at 1.63 eV was observed in Cr-doped CuGaS2 films. ; This work was supported by Ministerio de Economia y Competitividad (ENE2013-46624-C4-4-R) and Generalitat Valenciana (Prometeus 2014/044). One of the authors (S. Ullah) acknowledges the European Union (IDEAS-Call-3, Innovation and Design for Euro-Asian scholars) for its financial support. ; Ullah, S.; Mollar García, MA.; Marí, B. (2016). Electrodeposition of CuGaSe2 and CuGaS2 thin films for photovoltaic applications. Journal of Solid State Electrochemistry. 20(8):2251-2257. https://doi.org/10.1007/s10008-016-3237-0 ; S ; 2251 ; 2257 ; 20 ; 8 ; Calixto ME, Sebastian PJ, ...

International audience ; RATIONALE: Rare earth-doped sulphide glasses in the Ga-Ge-Sb-S system present radiative emissions from the visible to the middle infrared range (mid-IR) range, which are of interest for a variety of applications including (bio)-chemical optical sensing, light detection, and military counter-measures. The aim of this work was to reveal structural motifs present during the fabrication of thin films by plasma deposition techniques as such knowledge is important for the optimization of thin film growth. METHODS: The formation of clusters in plasma plume from different concentrations of erbium-doped Ga5 Ge20 Sb10 S65 glasses (0.05, 0.1, and 0.5 wt. % of erbium) using laser (337 nm) desorption ionization (LDI) was studied by time-of-flight mass spectrometry (TOF MS) in both positive and negative ion mode. The stoichiometry of the Gam Gen Sbo Sp (+/-) clusters was determined via isotopic envelope analysis and computer modelling. RESULTS: Several Gam Gen Sbo Sp (+/-) singly charged clusters were found but, surprisingly, only four species (Sb3 S4 (+/-) , GaSb2 Sp (+/-) (p = 4, 5), Ga3 Sb2 S7 (+/-) ) were common to both ion modes. For the first time, species containing rare earths (GaSb2 SEr(+) and GaS6 Er2 (+) ) were identified in the plasma formed from rare earth-doped chalcogenide glasses, directly confirming the importance of gallium presence for rare earth bonding within the glassy matrix. CONCLUSIONS: The local structure of Ga-Ge-Sb-S glasses is at least partly different from the structure of species identified in plasma by mass spectrometry, as deduced from Raman scattering spectroscopy analysis; these glasses are mainly formed by [GeS4/2 ]/[GaS4/2 ] tetrahedra and [SbS3/2 ] pyramids. Extended X-ray absorption fine structure measurements show that Er(3+) ions in Ga-Ge-Sb-S glasses are surrounded by 7 sulphur atoms. Copyright © 2014 John Wiley & Sons, Ltd.

International audience ; RATIONALE: Rare earth-doped sulphide glasses in the Ga-Ge-Sb-S system present radiative emissions from the visible to the middle infrared range (mid-IR) range, which are of interest for a variety of applications including (bio)-chemical optical sensing, light detection, and military counter-measures. The aim of this work was to reveal structural motifs present during the fabrication of thin films by plasma deposition techniques as such knowledge is important for the optimization of thin film growth. METHODS: The formation of clusters in plasma plume from different concentrations of erbium-doped Ga5 Ge20 Sb10 S65 glasses (0.05, 0.1, and 0.5 wt. % of erbium) using laser (337 nm) desorption ionization (LDI) was studied by time-of-flight mass spectrometry (TOF MS) in both positive and negative ion mode. The stoichiometry of the Gam Gen Sbo Sp (+/-) clusters was determined via isotopic envelope analysis and computer modelling. RESULTS: Several Gam Gen Sbo Sp (+/-) singly charged clusters were found but, surprisingly, only four species (Sb3 S4 (+/-) , GaSb2 Sp (+/-) (p = 4, 5), Ga3 Sb2 S7 (+/-) ) were common to both ion modes. For the first time, species containing rare earths (GaSb2 SEr(+) and GaS6 Er2 (+) ) were identified in the plasma formed from rare earth-doped chalcogenide glasses, directly confirming the importance of gallium presence for rare earth bonding within the glassy matrix. CONCLUSIONS: The local structure of Ga-Ge-Sb-S glasses is at least partly different from the structure of species identified in plasma by mass spectrometry, as deduced from Raman scattering spectroscopy analysis; these glasses are mainly formed by [GeS4/2 ]/[GaS4/2 ] tetrahedra and [SbS3/2 ] pyramids. Extended X-ray absorption fine structure measurements show that Er(3+) ions in Ga-Ge-Sb-S glasses are surrounded by 7 sulphur atoms. Copyright © 2014 John Wiley & Sons, Ltd.

Metal oxides based gas sensors are widely used in industrial, military and environmental applications. But the main fault of these sensors remains on their lack of selectivity and requiring high working temperature to obtain a good sensitivity. Nanostructuration of the materials presents an efficient way to enhance the reaction surface between gas and the host material, thus improving the sensor performance. ZnO is an n-type semiconductor with large bandgap energy of 3.37 eV at room temperature owning many interesting physical and chemical properties, and is also very sensitive for reducing gases. In recent years, many studies develop and improve the ZnO related nanostructures for various applications. The goal of this thesis consists in the synthesis of the ZnO nanowire arrays via hydrothermal method and the study of their sensing properties. The first part of this work shows a systematic study of the various influencing parameters during the ZnO nanowire synthesis. The results show that the growth temperature, the solution pH value and the growth time influence the nanowire morphology. Nanowires with an aspect ratio about 30 have been obtained under optimized growth conditions. The second part of this work consists of the study of the ZnO nanowire sensing properties, using both electrical and optical methods. The electrical measurements show a resistivity variation of the nanowires, while the UV absorption spectra reveal a bandgap shift under injected gas. A resistivity reduction and a blue-shift of a bandgap of the ZnO nanowires were observed under injected reducing gas such as ethanol ; Les capteurs de gaz à base d'oxydes métalliques connaissent un engouement croissant pour des applications industrielles, militaires et environnementales. Néanmoins, ces capteurs se montrent peu sélectifs et nécessitent des températures de travail élevées pour obtenir une bonne sensibilité. La nanostructuration des matériaux permet d'augmenter la surface de réaction entre le gaz et le matériau hôte, améliorant ainsi la ...

The experiment at HASYLAB/DESY was performed within the project I-20180036 EC. The research leading to this result has been supported by the project CALIPSOplus under the Grant Agreement 730872 from the EU Framework Programme for Research and Innovation HORIZON 2020. Filipe Correia is grateful to the Fundação para a Ciência e Tecnologia (FCT, Portugal) for the Ph.D. Grant SFRH/BD/111720/2015 . Joana Ribeiro is grateful to the Project WinPSC - POCI-01-0247-FEDER-017796, for the research grant, co-funded by the European Regional Development Fund (ERDF) , through the Operational Programme for Competitiveness and Internationalisation (COMPETE 2020), under the PORTUGAL 2020 Partnership Agreement. The authors acknowledge the funding from the following institution Fundação para a Ciência e Tecnologia (FCT, Portugal) /PIDDAC through the Strategic Funds project reference UID/FIS/04650/2013. The Spanish Ministry of Economy, Industry, and Competitiveness through the "Severo Ochoa" Program for Centers of Excellence in R&D (SEV-2015-0496), projects No. MAT2017-90024-P (TANGENTS)-EI/FEDER and MAT2015-70850-P (HIBRI2), and the Generalitat de Catalunya through grant 2017-SGR-00488 . M. K. acknowledges the Ph.D. programme in Materials Science from Universitat Autonoma de Barcelona in which she is enrolled. ; Transparent n-type niobium-doped titanium dioxide thin films (TiO2:1.5 at.%Nb) with pronounced thermoelectric properties were produced from a composite Ti:Nb target by reactive magnetron sputtering. The thin films were comprehensively characterized by X-ray diffraction, X-ray photoelectron spectroscopy, optical spectroscopy, electrical conductivity, and thermoelectric measurement techniques. The local structure of the thin films was investigated in detail by X-ray absorption spectroscopy at the Ti and Nb K-edges. A set of radial distribution functions were extracted from the simultaneous analysis of EXAFS data at two absorption edges using the reverse Monte Carlo method. It was found that Nb dopant atoms modify the local environment of the films, but their average structure remains close to that of the anatase phase. This conclusion is also supported by the ab initio simulations of XANES. A very high absolute Seebeck coefficient (S = 155 μV/K) for n-type TiO2 was achieved with Nb doping, yielding a maximum power factor and thermoelectric figure of merit of 0.5 mW m−1 K−2 and 0.18 at a temperature of 300 K, respectively, for a 150 nm thick film. From frequency-domain thermoreflectance experiments, a thermal conductivity value of 1.3 W m−1 K−1 was obtained for the optimized TiO2:Nb film. ; Fundo Regional para a Ciência e Tecnologia POCI-01-0247-FEDER-017796; Generalitat de Catalunya 2017-SGR-00488; MAT2015-70850-P,HIBRI2; SEV-2015-0496,MAT2017-90024-P; UID/FIS/04650/2013; European Regional Development Fund; Institute of Solid State Physics, University of Latvia as the Center of Excellence has received funding from the European Union's Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under grant agreement No. 739508, project CAMART²

The search of compounds emitting in the near-infrared (NIR) has been accelerated owing to their use in biomedical and telecommunications applications. In this regard, nanographenes (NGs) are attractive materials adequate for integration with other technologies, which have recently demonstrated amplified spontaneous emission (ASE) and lasing across the visible spectrum. Here, the optical and ASE properties of four-zigzag edged NGs of the [m,n]peri-acenoacene family are reported, whose size is increased through conjugation extension by varying n (from 3 to 5) while keeping m = 2. Results show that such 1D conjugation extension method is more efficient in terms of shifting the photoluminescence (PL) to the infrared (PL at 710 nm in the larger compound, PP-Ar) than through 2D conjugation extension as in previously reported NGs (PL at 676 nm with the largest compound FZ3, with n = 3 and m = 4). Additionally, PP-Ar shows dual-ASE (at 726 and 787 nm), whose origin is elucidated through Raman and transient absorption spectroscopies. These compounds' potential for red and NIR lasing is demonstrated through the fabrication of distributed feedback lasers with top-layer resonators. This study paves the way towards the development of stable low-cost all-plastic NIR lasers. ; The authors acknowledge financial support from the "Ministerio de Ciencia, Innovación y Universidades" of Spain, European Regional Development Fund and European Social Funds (MAT2015-66586-R, PDI2019-106114GB-I00, BES-2016-077681, PGC2018-098533-B-100 and RED2018-102815-T). J.C. thanks the Junta de Andalucía of Spain (UMA18FEDERJA057). The authors also thank the Research Central Services (SCAI) of the University of Málaga. F.G. acknowledges the Spanish Government for an FPI grant. G.M.P. thanks Fondazione Cariplo (grant no 2018-0979) for the financial support. J.W. acknowledges the "Agency for Science, Technology and Research of Singapore" for financial support from A*STAR AME grant (A20E5c0089). A.M.R. and F.S. have received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (grant agreement No. [816313]).

In organic solar cells, photogenerated singlet excitons form charge transfer (CT) complexes, which subsequently split into free charge carriers. Here, the contributions of excess energy and molecular quadrupole moments to the charge separation process are considered. The charge photogeneration in two separate bulk heterojunction systems consisting of the polymer donor PTB7-Th and two non-fullerene acceptors, ITIC and h-ITIC, is investigated. CT state dissociation in these donor–acceptor systems is monitored by charge density decay dynamics obtained from transient absorption experiments. The electric field dependence of charge carrier generation is studied at different excitation energies by time delayed collection field (TDCF) and sensitive steady-state photocurrent measurements. Upon excitation below the optical gap, free charge carrier generation becomes less field dependent with increasing photon energy, which challenges the view of charge photogeneration proceeding through energetically lowest CT states. The average distance between electron–hole pairs at the donor–acceptor interface is determined from empirical fits to the TDCF data. The delocalization of CT states is larger in PTB7-Th:ITIC, the system with larger molecular quadrupole moment, indicating the sizeable effect of the electrostatic potential at the donor–acceptor interface on the dissociation of CT complexes. ; The work of M.S., P.S.M. and C.D. received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie Grant Agreement No. 722651 (SEPOMO). The work of C.W. and C.G. was funded by the DFG (project DE 830/19-1). The work of S.K., F.L. and J.G. was supported by funding from King Abdullah University of Science and Technology (KAUST). This publication is based on work supported by the KAUST Office of Sponsored Research (OSR) under award nos. OSR-2018-CARF/CCF-3079 and OSR-CRG2018-3746. D.A. acknowledges KAUST for funding his sabbatical stay. A.M. acknowledges funding from the European Union's Horizon 2020 research and innovation program under the Marie Skłodowska-Curie Grant Agreement No. 844655 (SMOLAC). The authors thank the MATRIX SFR of the University of Angers.

Increases in the extent and level of air pollution in Chinese cities have become a major concern of the public and burden on the government. While ample literature has focused on the status, changes and causes of air pollution (particularly on PM2.5 and PM10), significantly less is known on their effects on people. In this study we used Hangzhou, China, as our testbed to assess the direct impact of PM2.5 on youth populations that are more vulnerable to pollution. We used the ground monitoring data of air quality and Aerosol optical thickness (AOT) product from the Moderate Resolution Imaging Spectroradiometer (MODIS) for the spatiotemporal changes of PM2.5 by season in 2015. We further explored these distributions with land cover, population density and schools (kindergarten, primary school and middle school) to explore the potential impacts in seeking potential mitigation solutions. We found that the seasonal variation of PM2.5 concentration was winter > ; spring > ; autumn > ; summer. In Hangzhou, the percentage of land area exposed to PM2.5 > ; 50 µ ; g m&minus ; 3 accounted for 59.86% in winter, 56.62% in spring, 40.44% in autumn and 0% in summer, whereas these figures for PM2.5 of < ; 35 µ ; g m&minus ; 3 were 70.01%, 5.28%, 5.17%, 4.16% in summer, winter, autumn and spring, respectively. As for land cover, forest experienced PM2.5 of 35&ndash ; 50 µ ; g m&minus ; 3 (i.e., lower than those of other cover types), likely due to the potential filtering and absorption function of the forests. More importantly, a quantitative index based on population-weighted exposure level (pwel) indicated that only 9.06% of the population lived in areas that met the national air quality standards. Only 1.66% (14,055) of infants and juveniles lived in areas with PM2.5 of < ; 35 µ ; g m&minus ; 3. Considering the legacy effects of PM2.5 over the long-term, we highly recommend improving the monitoring systems for both air quality and people (i.e., their health conditions), with special attention paid to infants and juveniles.

© 2016 [year] Optical Society of America.]. One print or electronic copy may be made for personal use only. Systematic reproduction and distribution, duplication of any material in this paper for a fee or for commercial purposes, or modifications of the content of this paper are prohibited. ; Solar illumination at ground level is subject to a good deal of change in spectral and colorimetric properties. With an aim of understanding the influence of atmospheric components and phases of daylight on colorimetric specifications of downward radiation, more than 5,600,000 spectral irradiance functions of daylight, sunlight, and skylight were simulated by the radiative transfer code, SBDART [Bull. Am. Meteorol. Soc. 79, 2101 (1998).], under the atmospheric conditions of clear sky without aerosol particles, clear sky with aerosol particles, and overcast sky. The interquartile range of the correlated color temperatures (CCT) for daylight indicated values from 5712 to 7757 K among the three atmospheric conditions. A minimum CCT of ∼3600 K was found for daylight when aerosol particles are present in the atmosphere. Our analysis indicated that hemispheric day-light with CCT less than 3600 K may be observed in rare conditions in which the level of aerosol is high in the atmosphere. In an atmosphere with aerosol particles, we also found that the chromaticity of daylight may shift along the green–purple direction of the Planckian locus, with a magnitude depending on the spectral extinction by aerosol particles and the amount of water vapor in the atmosphere. The data analysis showed that an extremely high value of CCT, in an atmosphere without aerosol particles, for daylight and skylight at low sun, is mainly due to the effect of Chappuis absorption band of ozone at ∼600 nm. In this paper, we compare our data with well-known observations from previous research, including the ones used by the CIE to define natural daylight illuminants. ; Andalusian Regional Government (P12-RNM-2409); Spanish Ministry of Science and Technology (CGL2013-45410-R); EU via the ACTRIS project (EU INFRA-2010-1.1.16-262254); Spanish Ministry of Economy and Competitiveness (DPI2011-23202).