Radiation Spectral Analysis of 3D Dust Molecular Clusters(PAHs)and Peptoids under Ionization and Electric Field in ISM

Polycyclic aromatic hydrocarbons(PAHs),PANHs,and peptoids dust spectral calculations from the interstellar medium(ISM)are important for dust observations and theory.Our goal is to calculate the radiation spectrum of spherical PAHs dust clusters in a vacuum containing ionized and applied in the presence of an electric field.We propose a new simple computational model to calculate the size of three-dimensional spherical dust clusters formed by different initial dust structures.By the Vienna Ab-initio Simulation Package code,the density functional theory with the generalized approximation was used to calculate the electron density gradient and obtain the radiation spectrum of dust.When the radius of spherical dust clusters is~[0.009-0.042]μm,the dust radiation spectrum agrees well with the Z=0.02 mMMP stellar spectra,and the PAHs radiation spectrum of NGC 4676 at wavelengths of(0-5]μm and(5-10]μm,respectively.In the ionized state,the N-PAH,C_(10)H_(9)N,2(C_(4)H_(4))^(1+),and peptoids 4(CHON),(C_(8)H_(10)N_(2)O_(5))^(1+)dust clusters at 3.3μm,while the 2(C_(22)H_(21)N_(3)O_(2))^(1+),4(CHON)dust clusters at 5.2μm have obvious peaks.There is a characteristic of part of PAHs and peptoids clusters radiation at the nearinfrared wavelength of 2μm.However,especially after applying an electric field to the dust,the emission spectrum of the dust increases significantly in the radiation wavelength range[3-10]μm.Consequently,the dust clusters of PAHs,PANHs,and peptoids of the radius size~[0.009-0.042]μm are likely to exist in the ISM.

2D Nb_(2)CT_(x) MXene/MoS_(2) heterostructure construction for nonlinear optical absorption modulation

Two-dimensional(2D)nonlinear optical mediums with high and tunable light modulation capability can significantly stimulate the development of ultrathin,compact,and integrated optoelectronics devices and photonic elements.2D carbides and nitrides of transition metals(MXenes)are a new class of 2D materials with excellent intrinsic and strong light-matter interaction characteristics.However,the current understanding of their photo-physical properties and strategies for improving optical performance is insufficient.To address this issue,we rationally designed and in situ synthesized a 2D Nb_(2)C/MoS_(2) heterostructure that outperforms pristine Nb2C in both linear and nonlinear optical performance.Excellent agreement between experimental and theoretical results demonstrated that the Nb_(2)C/MoS_(2) inherited the preponderance of Nb_(2)C and MoS_(2) in absorption at different wavelengths,resulting in the broadband enhanced optical absorption characteristics.In addition to linear optical modulation,we also achieved stronger near infrared nonlinear optical modulation,with a nonlinear absorption coefficient of Nb_(2)C/MoS_(2) being more than two times that of the pristine Nb_(2)C.These results were supported by the band alinement model which was determined by the X-ray photoelectron spectroscopy(XPS)experiment and first-principal theory calculation.The presented facile synthesis approach and robust light modulation strategy pave the way for broadband optoelectronic devices and optical modulators.

Coupling Stacking Orders with Interlayer Magnetism in Bilayer H-VSe2

Stacking-dependent magnetism in van der Waals materials has caught intense interests.Based on the first principle calculations,we investigate the coupling between stacking orders and interlayer magnetic orders in bilayer H-VSe 2.It is found that there are two stable stacking orders in bilayer H-VSe 2,named AB-stacking and A′B-stacking.Under standard DFT framework,the A′B-stacking prefers the interlayer AFM order and is semiconductive,whereas the AB-stacking prefers the FM order and is metallic.However,under the DFT+U framework both the stacking orders prefer the interlayer AFM order and are semiconductive.By detailedly analyzing this difference,we find that the interlayer magnetism originates from the competition between antiferromagnetic interlayer super-superexchange and ferromagnetic interlayer double exchange,in which both the interlayer Se-4 p z orbitals play a crucial role.In the DFT+U calculations,the double exchange is suppressed due to the opened bandgap,such that the interlayer magnetic orders are decoupled with the stacking orders.Based on this competition mechanism,we propose that a moderate hole doping can significantly enhance the interlayer double exchange,and can be used to switch the interlayer magnetic orders in bilayer VSe 2.This method is also applicable to a wide range of semiconductive van der Waals magnets.

基于界面热力学的电解质策略调控正极电压和能量密度

界面热力学对电池体系的诸多电化学性质(如电压)有着巨大的影响.水系锌锰电池由于其廉价、安全的特性有望被用于大规模储能,进一步提高能量密度是其实际应用的关键.为了提高水系锌离子电池的能量密度,是否可以从电解液的角度调控电极/电解液界面的热力学性质,从而进一步提高高容量锌锰电池体系的工作电压呢?本文首先从界面热力学的角度建立了电解质中阳离子类型与正极电极电位之间的关系.结果发现,含高价阳离子的电解质通过增加界面双电层中电极表面的电荷密度,进而提高正极侧的电极电位.考虑到锌锰电池的可逆性,本文认为含铝电解液是提高锌锰电池能量密度最有希望的电解液类型.接着利用能级分裂理论详细地解释了高电压锌锰电池在循环过程中复杂的电压平台变化.最后通过混合态电解质策略降低水溶剂的活性,实现了高电压锌锰电池的稳定循环.