- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
MatMix 1.0: Using optical mixing to probe visual material perception
摘要： MatMix 1.0 is a novel material probe we developed for quantitatively measuring visual perception of materials. We implemented optical mixing of four canonical scattering modes, represented by photographs, as the basis of the probe. In order to account for a wide range of materials, velvety and glittery (asperity and meso-facet scattering) were included besides the common matte and glossy modes (diffuse and forward scattering). To test the probe, we conducted matching experiments in which inexperienced observers were instructed to adjust the modes of the probe to match its material to that of a test stimulus. Observers were well able to handle the probe and match the perceived materials. Results were robust across individuals, across combinations of materials, and across lighting conditions. We conclude that the approach via canonical scattering modes and optical mixing works well, although the image basis of our probe still needs to be optimized. We argue that the approach is intuitive, since it combines key image characteristics in a "painterly" approach. We discuss these characteristics and how we will optimize their representations.
关键词： material probe,reflectance,BRDF,material perception,MatMix 1.0
更新于2025-09-04 15:30:14
-
European Microscopy Congress 2016: Proceedings || Factors limiting the doping efficiency in atomic layer deposited ZnO:Al thin films: a dopant distribution study by transmission electron microscopy and atom probe tomography
摘要： Transparent conducting oxides (TCOs), such as indium tin oxide (ITO), are commonly used as transparent electrodes in a wide variety of devices, such as in displays and solar cells. ZnO has been reported to be a promising alternative TCO for ITO, because of its lower cost. As the conductivity of intrinsic ZnO films is too low for the applications in mind, doping the ZnO film is essential, the most common dopant being Al. Atomic layer deposition (ALD) is an emerging technique for the deposition of doped ZnO thin films, allowing for accurate thickness control and excellent conformality on high aspect ratio topologies. Due to the self-limiting half-reactions and cyclic nature of the ALD process, not only the aforementioned characteristics can be met, but also the amount and distribution of dopants can be controlled by selecting the precursors (i.e. the Zn or Al precursors) for each individual half-cycle. However, thus far, the maximum conductivity that can be obtained in Al-doped ZnO (ZnO:Al) thin films prepared by ALD appears to be limited by the low doping efficiency of Al. To better understand the origin of this limitation, the 3-dimensional distribution of Al atoms in ZnO films has been examined using a combination of Transmission Electron Microscopy (TEM) and Atom Probe Tomography (APT). For this study, three ZnO:Al films with different Al:Zn ratios were grown sequentially in one film stack, and capped and separated by intrinsic ZnO films. A diagram of the stack is shown in Fig. 1a. This geometry allowed a single APT or TEM measurement to collect data on all three doped films, keeping the analytical conditions identical. BFTEM studies (Fig 1b) showed that for high Al concentrations the ZnO grains are interrupted, while they continue across the lower doped layers. Scanning TEM – High Angle Annular Dark Field (HAADF) imaging and 2-D EDX mappings allows for revealing the aluminum distribution as a function of film depth, showing that the Al-doped layers follow the surface topography of the ZnO grains during growth Fig. 1c,d. However, TEM is limited in providing 3-D dopant distributions, on the one hand because of the limited sensitivity of EDX, on the other hand because of the projection of rough interfaces in a 2-D image. The latter is illustrated in Fig. 2a: individual Al-doped layers can clearly be discerned for larger interspacings, but are poorly recognizable in layer ‘AZO-3’. One-dimensional depth profiles extracted from cylindrical sub-volumes of the 3D APT data (Fig. 2 b) are presented in Fig. 2c. These 1D profiles show that the peaks in Al concentration are no δ-functions, as might be expected from the binary nature of the ALD process. Instead, the peaks have a full width at half maximum (FWHM) of ~2 nm. The 3-dimensional dopant distribution can be used to explain the dependencies of resistivity and doping efficiency on growth recipes used. When the local Al density is too high, the doping efficiency is limited by two proposed limiting factors: the solid solubility limit of Al atoms in a ZnO matrix and the disorder-induced carrier localization.
关键词： atom probe tomography,atomic layer deposition,transparent conducting oxides
更新于2025-09-04 15:30:14
-
Pump-Push-Probe for Ultrafast All-Optical Switching: The Case of a Nanographene Molecule
摘要： In the last two decades, the three-beam pump–push–probe (PPP) technique has become a well-established tool for investigating the multidimensional configurational space of a molecule, as it permits disclosure of precious information about the multiple and often complex deactivation pathways of the excited molecule. From the spectroscopic point of view, such a tool has revealed details about the efficiency of charge pair generation and conformational relaxation in π-conjugated molecules and macromolecules. In addition, PPP is effectively utilized for modulating the gain signal in conjugated materials by taking advantage of the spectral overlap between stimulated emission and charge absorption in those systems. However, the relatively low stability of conjugated polymers under intense photoexcitation is a crucial limitation for their real employment in plastic optical fibers (POFs) and for signal control applications. Herein, the role of PPP for achieving ultrafast all-optical switching in π-conjugated systems is highlighted. Furthermore, new experimental data on optical switching of a newly synthesized nanographene molecule, namely dibenzo[hi,st]ovalene (DBOV), is reported. The superior environmental and photostability of DBOV and, in general, of graphene nanostructures can represent a great advantage for their effective applications in POFs and information and communications technology.
关键词： ultrafast optical switching,pump–push–probe,conjugated polymers,ultrafast spectroscopy,nanographene
更新于2025-09-04 15:30:14
-
Temporally Resolving Synchronous Degenerate and Nondegenerate Two-Photon Absorption in 2D Semiconducting Monolayers
摘要： Degenerate and nondegenerate two-photon absorption (TPA) in WS2 and MoSe2 monolayers are synchronously induced and temporally resolved by femtosecond laser pump-probe. Di?erential transmission signals in the ?rst 500 fs consist of negative and positive components, that originate from direct probe depletion via nondegenerate TPA and carrier accumulation via degenerate TPA, respectively. Temporal cross-correlation of pump and probe pulses allows us to fully decouple the ultrafast nondegenerate and degenerate TPA signals. Subsequently, degenerate and nondegenerate TPA coe?cients are calculated as a function of pump irradiance. Under nonresonant pumping, 100 ± 10 and 250 ± 25 cm GW?1 are obtained for degenerate and nondegenerate TPA coe?cients of monolayer WS2, respectively, which both present linearly decreasing trends as increasing pump irradiances. However, under resonant pumping of 2 p excitonic states in monolayer MoSe2, degenerate TPA coe?cients exponentially decrease from 800 to 80 cm GW?1 as increasing pump irradiances, due to the interplay between band-renormalization and band-?lling e?ects, while nondegenerate TPA coe?cient is about 650 ± 50 cm GW?1. For comparison, a trilayer MoSe2 is also investigated. These results set a foundation for precisely measuring TPA coe?cients and actively controlling nonlinear excitonic dynamics via TPA in 2D semiconducting monolayers.
关键词： 2D monolayer,transition metal dichalcogenide,femtosecond laser pump-probe,nondegenerate two-photon absorption,degenerate two-photon absorption
更新于2025-09-04 15:30:14
-
MULTI-BAND CYLINDRICAL DIELECTRIC RESONATOR ANTENNA USING PERMITTIVITY VARIATION IN AZIMUTH DIRECTION
摘要： A novel multi-band cylindrical dielectric resonator antenna (CDRA) using microwave laminates with permittivity variation in azimuth direction fed by coaxial probe is proposed in this paper. The proposed structures are constructed using di?erent materials having di?erent permittivities in azimuth direction in cylindrical dielectric resonator (DR). In order to determine the performance of various design parameters on resonance frequency and bandwidth, parametric studies have been performed. The operating band can be scaled up or down by adjusting the design parameters. Dual-band and triple-band CDRAs have been fabricated using commercially available microwave laminates to validate the simulation results. For each case, the input re?ection coe?cient, radiation pattern and antenna gain are simulated and measured. Good agreement between simulated and measured results has been observed. The proposed antennas may be suitable for WLAN applications.
关键词： WLAN applications,coaxial probe,multi-band,azimuth direction,permittivity variation,cylindrical dielectric resonator antenna
更新于2025-09-04 15:30:14
-
Electron/Energy Transfer Studies on Hybrid Materials Based on Dinuclear Coordination Compounds of Twisted Perylene Diimide
摘要： To understand the influence of transition metal ion coordination on the properties and performance of the triads, the symmetric bridging ligand, 1,10-phenanthroline-perylene diimide-1,10-phenanthroline, 1,10-Phen-PDI-1,10-Phen (1) comprising four electron-donating 4-methoxyphenoxy bulky groups at bay-positions and its corresponding square-planar coordination compounds with dichloroplatinum(II), [{PtCl2}2-1] (2) and palladium(II) [{PdCl2}2-1] (3) were prepared in order to tune the photochemical and optical properties of these hybrid materials. These triads show strong electronic absorption bands attributed to the PDI and M(II)(1,10-Phen)Cl2 moieties in DMSO. UV-Vis absorption spectra of compounds were calculated using Time-Dependent Density Functional Theory (TDDFT) for the ground state optimized structures in DCM. Current results indicate that 2 has the lowest HOMO-LUMO gap (2.29 eV in DCM) among the investigated molecules. The energy and charge transfer processes with tailoring molecular structures are one of the important strategies for the design of future functional triads based on donor and acceptor moieties for hybrids optoelectronic devices. Thus, we studied linear absorption, fluorescence, and ultrafast transient absorption spectra measurements for the triads in dichloromethane to investigate the impact of different functionalization strategies on the optical characteristics, photo-stability, and photo-induced charge-transfer (CT) processes. The observed ultrafast intramolecular charge transfer from donor units to acceptor part of 1, 2 and 3 is related to fluorescence quenching and faster singlet state decay on transient absorption measurements. The intramolecular charge transfer mechanism was also compared with the unsymmetrical counterparts that were investigated previously. Symmetrical compounds exhibit faster charge transfer in comparison with the unsymmetrical compounds.
关键词： density functional theory,coordination compounds,ultrafast pump-probe,Perylene diimide,hybrid materials
更新于2025-09-04 15:30:14
-
Dicyanoisophorone-Based Near-Infrared Emission Fluorescent Probe for Detecting NAD(P)H in Living Cells and <i>in Vivo</i>
摘要： NADH and NADPH are ubiquitous coenzymes in all living cells and play vital roles in numerous redox reactions in cellular energy metabolism. To accurately detect the distribution and dynamic changes of NAD(P)H under physiological condition is essential for understanding its biological functions and pathological roles. In this work, we developed a near-infrared (NIR) emission fluorescent small-molecule probe (DCI-MQ) composed of a dicyanoisophorone chromophore conjugated with a quinolinium moiety for in vivo NAD(P)H detection. DCI-MQ owns the advantages of high water solubility, rapid response, extraordinary selectivity, great sensitivity (detection limit of 12 nM), low cytotoxicity and a NIR emission (660 nm) in response to NAD(P)H. Moreover, the probe DCI-MQ was successfully applied for the detection and imaging of endogenous NAD(P)H in both living cells and tumor-bearing mice, which provides an effective tool for the study of NAD(P)H-related physiological and pathological processes.
关键词： NAD(P)H,near-infrared emission,fluorescent probe,bioimaging,dicyanoisophorone
更新于2025-09-04 15:30:14
-
Selectively light-up hydrogen peroxide in hypoxic cancer cells with a novel fluorescent probe
摘要： A novel fluorescent turn-on probe (HCyHP) was developed in a simple two-step synthesis for monitoring of exogenous and endogenous H2O2 levels in biological samples and hypoxic cancer diagnosis.
关键词： hypoxic cancer cells,fluorescent probe,hydrogen peroxide,bioimaging,diagnosis
更新于2025-09-04 15:30:14
-
Ultra-Sensitive and Label-Free Probing of Binding Affinity Using Recognition Imaging
摘要： Reliable quantification of binding affinity is important in biotechnology and pharmacology and increasingly coupled with a demand for ultrasensitivity, nanoscale resolution, and minute sample amounts. Standard techniques are not able to meet these criteria. This study provides a new platform based on atomic force microscopy (AFM)-derived recognition imaging to determine affinity by visualizing single molecular bindings on nanosize dendrons. Using DNA hybridization as a demonstrator, an AFM sensor adorned with a cognate binding strand senses and localizes target DNAs at nanometer resolution. To overcome the limitations of speed and resolution, the AFM cantilever is sinusoidally oscillated close to resonance conditions at small amplitudes. The equilibrium dissociation constant of capturing DNA duplexes was obtained, yielding 2.4 × 10?10 M. Our label-free single-molecular biochemical analysis approach evidences the utility of recognition imaging and analysis in quantifying biomolecular interactions of just a few hundred molecules.
关键词： scanning probe microscopy,DNA hybridization,Affinity,molecular recognition,single-molecule
更新于2025-09-04 15:30:14
-
Improvement of response time in GAGG:Ce scintillation crystals by magnesium codoping
摘要： Dynamics of the population of the excited Ce states responsible for the luminescence response time in Gd3Al2Ga3O12:Ce scintillating crystals is studied by revealing the dynamics of nonequilibrium carriers in the picosecond domain. Optical pump and probe technique exploiting selective excitation of structural units of the crystal and probing the induced absorption as a function of time and spectral position is exploited. A fast response within a few picoseconds due to the absorption by holes at Gd ions and by electrons occupying the first excited state of Ce ions with the intracenter relaxation time of 500 fs are identified. Trapping of nonequilibrium electrons during their migration through the matrix to the emitting Ce ions are shown to be responsible for the slow component in the population of the excited Ce state. Elimination of the slow component is evidenced even at Mg codoping as low as 10 ppm. The elimination correlates with the acceleration of the response in coincidence time resolution experiments showing potential of GAGG:Ce, Mg in medical and high-energy physics applications.
关键词： response time,nonequilibrium carriers,optical pump and probe technique,magnesium codoping,scintillation crystals,GAGG:Ce,coincidence time resolution
更新于2025-09-04 15:30:14