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81.
82.
83.
In the last few years, all‐inorganic perovskite CsPbBr3 nanocrystals (NCs) have attracted tremendous attention for its high carrier mobility, long carrier diffusion length, excellent visible light absorption, and more importantly superior air stability. In fact, photodetectors (PDs) are designed and fabricated using the CsPbBr3 NCs with very high performance. Herein, by optimizing the NC shape, size, and surface passivation, the CsPbBr3 PDs are developed with an even higher performance. It is found that the PDs based on CsPbBr3 nanoribbons show the best photoresponse among all common NC structures synthesized. Moreover, it is found that 6,6‐phenyl‐C61‐butyric acid ethyl ester can be used to passivate defects on the CsPbBr3 nanoribbon surface and shows the charge transfer. As a result, the device displays superior photoresponsivity (R = 18.4 A W−1), excellent signal‐to‐noise ratio, as high as 104, and a very sharp rise/decay time (8.7/3.5 ms). The method demonstrated may offer an attractive strategy to improve sensitivity for all‐inorganic perovskite PDs in general. 相似文献
84.
The surface profiler has become a basic metrology tool for the characterization of high-quality optical surfaces. The unknown effective resolution of the surface profiler is problematic in using the instrument, as it distorts the measured surface profile. In this paper, we suggest and describe the use of a fractal surface as a standard test surface with which to calibrate the effective resolution of a surface profiler. Fractal surfaces have the characteristics of irregularity, self-similarity and low correlation, with the correlation length being approximately equal to the length of the profile; therefore, a log-log plot of the power spectral density curve is a straight line. The power spectral density curves of fractal surfaces, which can be acquired through surface characterization techniques such as atomic force microscopy, are fitted to a straight line to act as a standard with which to calibrate an optical profiler in different ranges. Through calibration, we can obtain the effective resolution of the optical profiler, and the surface profiler is found to have good transmission capacity within the effective spatial frequency range. 相似文献
85.
This paper is devoted to the study of the underlying linearities of the coupled
Harry--Dym (cHD) soliton hierarchy, including the well-known cHD equation. Resorting
to the nonlinearization of Lax pairs, a family of finite-dimensional Hamiltonian
systems associated with soliton equations are presented, constituting the
decomposition of the cHD soliton hierarchy. After suitably introducing the
Abel--Jacobi coordinates on a Riemann surface, the cHD soliton hierarchy can be
ultimately reduced to linear superpositions,
expressed by the Abel--Jacobi variables. 相似文献
86.
87.
N. Shirakbari H. Salehi-Mobarakeh M. Khorasani 《Journal of Macromolecular Science: Physics》2014,53(7):1286-1292
The effect of surfactant type and concentration on the migration behavior of surfactant in a latex film was investigated. Two types of surfactant, including an anionic (sodium lauryl sulfate, SLS) and a non-ionic (nonylphenol ethoxylate, average number of ethylene oxide units = 40, NP-40) surfactant, were used in an emulsion polymerization of methyl methacrylate butyl acrylate copolymer (MMA–BA). The total amount of surfactant was varied in three levels, i.e., 1.5, 3, and 4.5 wt%, and the surfactants were used both pure and in a mixture state. The surfactant migration to the film–air (F–A) and film–substrate (F–S) interfaces of the latex films was determined by using an attenuated total reflection-Fourier transform infrared (ATR-FTIR) method. In addition, the adhesion of the latex films to glass substrates was measured by a pull-off test. The results showed that the migration of anionic surfactant to the interfaces was greater than the non-ionic one. It was also found that the use of non-ionic surfactant along with anionic surfactant could decrease the migration of the anionic surfactant to the interfaces. 相似文献
88.
The present series of papers summarizes the results of a three-year research project on the realistic simulation of car audio sound in car passenger compartments using a combined Finite Element (FE) and Geometrical Acoustics (GA) approach. The simulations are conducted for the whole audible frequency range with the loudspeakers of the car audio system as the sound sources. The challenges faced during the project relate to fundamental questions regarding the realistic sound field simulation in small enclosures with strong modal and diffraction effects.The paper denoted here as Part I focuses on boundary and source representations in the FE and GA domain and suggests guidelines for a best-possible acquisition of the required data. Since a straight-forward determination of the boundary and source characteristics is mostly hampered by the immense complexity and inhomogeneity of the materials and loudspeaker configurations inside a car compartment, different measurement and calculation methods have been applied to determine the required data and quantify the corresponding uncertainty. The paper clearly points out the strength and weaknesses of the applied methods depending on the considered frequency range and material characteristics. In order to keep the complexity of the FE simulations at a manageable level, all passive boundaries were considered as locally reacting with impedance conditions.Part II of the study applies the obtained data in combined FE-GA room acoustic simulations and compares the simulated room impulse responses (RIR) with corresponding measurement results. In a final step the observed differences in the RIRs are related to the uncertainty and inherent errors in the boundary and source representation. 相似文献
89.
Martin Dressel Olivier Klein Steve Donovan George Grüner 《International Journal of Infrared and Millimeter Waves》1993,14(12):2489-2517
The resonant cavity perturbation method as described in the preceding two parts of this series is applied to study the electrodynamical properties of different materials in the microwave and millimeter wave spectral range. We briefly discuss the relevant uncertainties which are asociated with the different measurement techniques and we find that employing the amplitude technique it is possible to measure both the width and frequency to nearly the same precision. We then demonstrate the broad range of applicability of this technique by showing results obtained on several different materials, ranging from an insulator to a superconductor. The performance limitations of this technique are discussed in detail. 相似文献
90.
The adsorption of NH3 molecule on the Si(1 1 1)-7 × 7 surface modelled with a cluster has been studied using density functional theory (DFT). The results indicate the existence of a precursor state for the non-dissociative chemisorption. The active site for the molecular chemisorption is the adatom; while the NH3 molecule adsorbs on the Si restatom via this preadsorbed state, the adsorption on the Si adatom is produced practically without an energy barrier. The ammonia adsorption on the adatom induces an electron transfer from the dangling bond of this atom to the dangling bond of the adjacent Si restatom, hindering this site for the adsorption of a second NH3 incoming molecule. However, this second molecule links strongly by means of two H-bonds. The dissociative chemisorption process was studied considering one and two ammonia molecules. For the dissociation of a lonely NH3 molecule an energy barrier of ∼0.3 eV was calculated, yielding NH2 on the adatom and H on the restatom. When two molecules are adsorbed, the NH3-NH3 interaction yields the weakening of a N-H bond of the ammonia molecule adsorbed closer the Si surface. As a consequence, the dissociation barrier practically disappears. Thus, the presence of a second NH3 molecule at the adatom-restatom pair of the Si(1 1 1)-7 × 7 surface makes the dissociative reaction self-assisted, the total adsorption process elapsing with a negligible activation barrier (less than 0.01 eV). 相似文献