便携式FTIR的机动车尾气检测方法

随着汽车排放标准的提高,相关VOC标准从总烃检测变为非甲烷碳氢化合物(NMHC)检测;随着含氧燃料的增加,增加了非甲烷有机气体(NMOG)测量.针对国内汽车尾气分析仪分析组分单一、精度有限、VOCs检测过程复杂等问题,提出了基于便携式FTIR的机动车尾气检测方法,基于立体角镜优化FTIR光学系统结构,提高动镜扫描速度,...     

Spin–phonon coupling in van der Waals antiferromagnet VOCl

We report magnetization and Raman spectroscopy study on single crystals of VOCl, a van der Waals antiferromagnetic material. Magnetization measurement confirms an antiferromagnetic transition at 79 K and a magnetic easy axis along crystallographic a direction. The temperature-dependent Raman spectrum reveals five peaks at 30 K. Below the Neel temperature TN, the Raman-active modes 247 cm~(-1) and 404 cm~(-1) remarkably deviate from the standard Boltzmann function,which is ascribed to the strong magnetoelastic coupling between spins and phonons. We further observe an anomaly in 383 cm~(-1) mode at around 150 K. This coincides with the broad maximum in VOCl's magnetic susceptibility, suggesting a development of short-ranged magnetic order at this temperature.     

Quantum Resources in Heisenberg XX Model Under Noisy Environment

International Journal of Theoretical Physics - In this paper, we investigate Einstein-Podolsky-Rosen steering, Bell non-locality, first-order coherence and concurrence in the spin- $\frac {1}{2}$...     

A theoretical kinetics study on low-temperature oxidation of n-C4H9 radicals

The low-temperature oxidation mechanism of n?butyl radicals (n-C₄H₉) has been investigated by high level quantum chemical calculations coupled with the Rice–Ramsperger–Kassel–Marcus/Master Equation (RRKM/ME) theory. The potential energy surfaces (PES) were explored at the QCISD(T)/CBS//B3LYP/6-311++G(d,p) level. The temperature- and pressure-dependent rate constants were computed and fitted in modified Arrhenius parameters. The major reaction channels were discussed to more deeply understand the competing relationships between chain branching, chain propagation and termination reactions. The results show that the 1,5 H-shift reaction is more competitive than the 1,6 H-shift and 1,4 H-shift for isomerization reactions of n?butyl peroxy radicals, and the concerted HO₂ elimination channel to form butene becomes more important at high temperatures. Furthermore, based on our calculations, a revised kinetic model was developed to describe n-butane oxidation. Good consistency between model predictions and experimental data was shown. This study enhances our understanding of the combustion mechanism of n-butane and can be used as a reliable reference for mechanistic understanding of larger alkanes.     

Diversity-oriented synthesis and antifungal activities of novel pimprinine derivative bearing a 1,3,4-oxadiazole-5-thioether moiety

Molecular Diversity - Based on the strategy of diversity-oriented synthesis and the structures of natural product pimprinine and streptochlorin, two series of novel pimprinine derivatives...     

Tunable dual-band terahertz graphene absorber with guided mode resonances

A tunable dual-band terahertz absorber is designed and investigated. The unit cell of the proposed absorber consists of a graphene monolayer on a guided-mode resonant filter. The graphene absorber presents > 40% absorption at two resonance frequencies, which is attributed to the guided mode resonances with different mode numbers. The electric field intensity distribution is analyzed to disclose the physical mechanism of such a dual-band absorption effect. Furthermore,the influence of optical properties of graphene, including Fermi level and relaxation time, on the absorption spectra are investigated. Finally, the influence of geometric parameters on the absorption spectrum is studied, which will provide useful guidance for the fabrication of this absorber. We believe that the results may be useful for developing the next-generation graphene-based optoelectronic devices.     

Broadband absorption enhancement with ultrathin MoS_2 film in the visible regime

The broadband absorption enhancement effect in ultrathin molybdenum disulfide(Mo S2)films is investigated.It is achieved by inserting the Mo S2 film between a dielectric film and a one-dimensional silver grating backed with a silver mirror.The broadband absorption enhancement in the visible region is achieved,which exhibits large integrated absorption and short-circuit current density for solar energy under normal incidence.The optical properties of the proposed absorber are found to be superior to those of a reference planar structure,which makes the proposed structure advantageous for practical photovoltaic application.Moreover,the integrated absorption and short-circuit current density can be maintained high for a wide range of incident angles.A qualitative understanding of such broadband absorption enhancement effect is examined by illustrating the electromagnetic field distribution at some selected wavelengths.The results pave the way for developing high-performance optoelectronic devices,such as solar cells,photodetectors,and modulators.     

Absence of magnetic order in dichloro [1,2-bis(diphenylphosphino)ethane] nickel~(2+) single crystal

Dichloro [1,2-bis(diphenylphosphino) ethane] nickel~(2+)(Ni Cl_2(dppe)) is an organic compound containing C_(26)H_(24)P_2(dppe) molecules and Cl-, Ni~(2+)ions. The large-size Ni Cl_2(dppe) single crystals with longest dimension of4 mm were grown by the method of slow evaporation of organic solution. Single crystal x-ray diffraction spectrum indicates that the single crystal is of high quality. Magnetization results of the Ni Cl_2(dppe) single crystals show an anisotropic paramagnetism behavior and diamagnetic background, which come from Ni~(2+) ions and benzene ring, respectively. However, according to the specific heat results with temperature down to 0.1 K and magnetic field up to 14 T, no expected field-induced quantum phase transition was observed in Ni Cl_2(dppe) single crystals.     

Controlled quantum teleportation of an unknown single-qutrit state in noisy channels with memory

This paper proposes a three-dimensional(3 D) controlled quantum teleportation scheme for an unknown single-qutrit state. The scheme is first introduced in an ideal environment, and its detailed implementation is described via the transformation of the quantum system. Four types of 3 D-Pauli-like noise corresponding to Weyl operators are created by Kraus operators: trit-flip, t-phase-flip, trit-phase-flip, and t-depolarizing. Then, this scheme is analyzed in terms of four types of noisy channel with memory. For each type of noise, the average fidelity is calculated as a function of memory and noise parameters, which is afterwards compared with classical fidelity. The results demonstrate that for trit-flip and t-depolarizing noises, memory will increase the average fidelity regardless of the noise parameter. However, for t-phase-flip and trit-phaseflip noises, memory may become ineffective in increasing the average fidelity above a certain noise threshold.