静止轨道高光谱海洋水色仪光学系统设计

设计了由超大口径前置望远系统和超大视场光谱仪组成的超大口径高光谱海洋水色仪.前置望远系统采用同轴三反光学系统结构,口径为4 m,视场为0.64°,焦距为21.6 m,波段范围为400~1 000nm.超大视场光谱仪采用改进的Offner结构,视场为240mm,光谱分辨率为10nm.探测器像元尺寸为15μm×15μm,4片探测器交错拼接实现400km幅宽.超大视场光谱仪在400~1 000nm的宽波段内,点列图半径的均方根值均小于3.9μm,静止轨道高光谱海洋水色仪全系统不同波长的MTF在33.3lp/mm处大于0.52,各项指标均满足应用要求.     

A giant enhancement of magnetic moment in a ternary three-shell icosahedral cluster: Fe@Mn12@Au20

ABSTRACT

The average magnetic moment per atom of Mn₁₃ cluster is expected to be enhanced by doping or coating with a shell. Several ternary core–shell icosahedral clusters TM@Mn₁₂@Au₂₀ were constructed by combining substituting the central Mn with VIII elements (Fe, Co, Ni, Ru, Rh, Pd and Pt) and coating with a icosahedral Au₂₀ shell, and systematically studied by using the first-principles density functional method. Compared to Mn₁₃, Fe@Mn₁₂@Au₂₀ cluster shows a giant enhancement on total magnetic moment (52?µ_B) which can be greatly attributed to the ferromagnetic coupling between spin moments of atoms. Coating with Au₂₀ shell enlarged the average distances of TM-Mn and Mn-Mn and is a useful way to change the magnetic coupling style. By analysis of density of states and electron localisation functional, we can conclude that the weak hybridisation between Fe and Mn in Fe@Mn₁₂@Au₂₀ is propitious to maintain their original direction of spin moments of atoms and then form ferromagnetic coupling.     

Ground state cooling of magnomechanical resonator in PT-symmetric cavity magnomechanical system at room temperature

We propose to realize the ground state cooling of magnomechanical resonator in a parity–time (PT)-symmetric cavity magnomechanical system composed of a loss ferromagnetic sphere and a gain microwave cavity. In the scheme, the magnomechanical resonator can be cooled close to its ground state via the magnomechanical interaction, and it is found that the cooling effect in PT-symmetric system is much higher than that in non-PT-symmetric system. Resorting to the magnetic force noise spectrum, we investigate the final mean phonon number with experimentally feasible parameters and find surprisingly that the ground state cooling of magnomechanical resonator can be directly achieved at room temperature. Furthermore, we also illustrate that the ground state cooling can be flexibly controlled via the external magnetic field.     

Efficient Quantum Dot Light-Emitting Diodes Based on Well-Type Thick-Shell CdxZn1−xS/CdSe/CdyZn1−yS Quantum Dots

Device grade quantum dots (QDs) require QDs ensembles to retain their original superior optical properties as in solution. QDs with thick shells are proven effective in suppressing the inter-dot interaction and preserving the emission properties for QDs solids. However, lattice strain–induced defects may form as the shell grows thicker, resulting in a notable photoluminescence quenching. Herein, a well-type Cd_xZn_1−xS/CdSe/Cd_yZn_1−yS QDs is proposed, where ternary alloys CdZnS are adopted to match the lattice parameter of intermediate CdSe by separately adjusting the x and y parameters. The resultant thick-shell Cd_0.5Zn_0.5S/CdSe/Cd_0.73Zn_0.27S QDs reveal nonblinking properties with a high PL QY of 99% in solution and 87% in film. The optimized quantum dot light-emitting diodes (QLEDs) exhibit a luminance of 31547.5 cd m⁻² at the external quantum efficiency maximum of 21.2% under a bias of 4.0 V. The shell thickness shows great impact on the degradation of the devices. The T₅₀ lifetime of the QLEDs with 11.2 nm QDs reaches 251 493 h, which is much higher than that of 6.5 and 8.4 nm QDs counterparts. The performances of the well-type thick-shell QLEDs are comparable to state-of-the-art devices, suggesting that this type of QDs is a promising candidate for efficient optoelectronic devices.     

Wavefront response matrix for closed-loop adaptive optics system based on non-modulation pyramid wavefront sensor

Pyramid wavefront sensor (PWFS) is a kind of wavefront sensor with high spatial resolution and high energy utilization. In this paper an adaptive optics system with PWFS as wavefront sensor and liquid-crystal spatial light modulator (LC-SLM) as wavefront corrector is built in the laboratory. The wavefront response matrix is a key element in the close-loop operation. It can be obtained by measuring the real response to given aberrations, which is easily contaminated by noise and influenced by the inherent aberration in the optical system. A kind of analytic solution of response matrix is proposed, with which numerical simulation and experiment are also implemented to verify the performance of closed-loop correction of static aberration based on linear reconstruction theory. Results show that this AO system with the proposed matrix can work steadily in closed-loop operation.     

Red,green and infrared three-wavelength lasers generated from LD side-pumped Nd3+:YAG crystal

To obtain 1064 nm/532 nm/660 nm three wavelength lasers operating simultaneously or singly, a novel LD side-pumped Nd³⁺:YAG laser system with acousto-optic Q-switched and nonlinear frequency conversion technologies was investigated. When the three wavelength lasers output singly and the Pumping power was 103 W, 1064 nm laser was 14.5 W and the green and red lasers reached 4.7 W and 1.6 W, respectively, at the repetition rate of 10.5 kHz and 11.5 kHz. When they worked simultaneously, the red, green and infrared lasers were obtained with the output power distribution of 1.0 W at 660 nm, 4.3 W at 532 nm and 10.1 W at 1064 nm, and the instability was less than 2% within 3 h.     

A theoretical investigation about sensing mechanism of fluoride anion for (E)‐2‐(2‐(dimethylamino)ethyl)‐6‐(4‐hydroxystyryl)‐1H‐benzo[de]‐isoquinoline‐1,3 (2H)‐dione

In the present work, we theoretical study the sensing mechanism of a new fluoride chemosensor (E)‐2‐(2‐(dimethylamino)ethyl)‐6‐(4‐hydroxystyryl)‐1H‐benzo[de]‐isoquinoline‐1,3(2H)‐dione (the abbreviation is NIM ). Based on density functional theory and time‐dependent density functional theory methods, the fluoride anion response mechanism has been confirmed via constructing potential energy curve. The exothermal deprotonation process along with the intermolecular hydrogen bond O–H···F reveals the uniqueness of detecting F^?. After capturing hydrogen proton forming NIM‐A anion configuration, a new absorption peak around 655 nm appears in dimethyl sulfoxide solvent. In addition, the emission of NIM can be quenched when adding F^? has been also confirmed. Due to the twisted intramolecular charge transfer character NIM‐A‐S ₁ form, we further verify the experimental phenomenon. The theoretical electronic spectra (vertical excitation energies and fluorescence peak) reproduced previous experimental results (ACS Appl. Mater. Interfaces 2014, 6, 7996), which not only reveals the rationality of our theoretical level used in this work but also confirms the correctness of geometrical attribution. In view of the excitation process, the strong intramolecular charge transfer process of S₀ → S₁ transition explain the redshift of absorption peak for NIM with the addition of fluoride anion. This work presents a straightforward sensing mechanism (deprotonation process) of fluoride anion for the novel NIM chemosensor.     

Experimental verification of enhanced transmission through two-dimensionally corrugated metallic films without holes

We present experimental results to verify extraordinary optical transmission through two-dimensionally periodic, corrugated metallic films without holes as predicted by Bonod et al. [Opt. Express 11, 482 (2003)]. We also experimentally confirmed that using symmetric structures (metallic films sandwiched between two identical dielectric media) is advantageous for boosting the coupling of surface plasmons so as to create strong transmission peaks.     

碳纳米纤维吸附储氢性能分析

文中综合碳纳米纤维微观结构的表征结果以及氢吸脱附等温线的实验测量结果,对碳纳米纤维的吸附储氢性能进行了综合分析,分析发现:比表面积和中孔容积均与氢吸附量成线性关系;微孔容积对材料吸附性能影响较大,微孔容积与氢吸附量成抛物线关系;氢在常温左右以及77K下的吸附等温线呈现超临界气体的吸附特征,氢在273K和353K下的吸脱附等温线也基本重合,呈现的是物理吸附的特征。实验结果还说明:常温左右,甚至是77K下,碳纳米纤维均不适合于氢的吸附储存。     

固体浸没透镜飞行高度的气浮控制

采用固体浸没透镜的光存储方法是提高光存储密度的比较实用的近场光存储方法,而严格控制SIL下底面与光存储介质之间的亚波长级距离是此光存储系统正常工作的前提.本文采用电容法测量SIL的飞行高度,采用弹性悬臂将SIL加载在转盘表面上,转盘以不同速度转动时SIL将悬浮在不同的高度.计算机首先采集到SIL的飞行高度信息,再与设定的飞行高度作比较,根据比较结果调整转盘转速,从而达到调整SIL飞行高度的目的.采用此方法,可以动态地将SIL的下底面控制在距高速转动的转盘表面上150～600 nm范围内的一定高度上.