对光子选择反射的光子晶体

对光子选择反射的光子晶体１９９１年首次演示的一种新型材料——光子晶体已找到首项应用。这种材料的光子行为类似半导体中的电子，它有一系列光子“禁戒”频率，在这些频率上，材料起着对光子的全反射作用。美国研究人员已把光子晶体用作微波微型天线反射镜，总有一天会...

Rovibrational State-Selectivity in Photoassociation through Multi-photon Transitions

The rovibrational state-selectivity in photoassociation （PA） is investigated for the ground electronic state of OH radical. The calculated results show that population can be transferred from continuum state to the target states through three-, four-, and nine-photon transitions by choosing suitable pulse parameters and initial collision energy. To control population transfer to a lower rovibrational state, a shorter pulse frequency has to be chosen and the photon number transferred to target state should be increased. In PA process, some associated OH radicals can be dissociated via intermediate and background states, which decreases the nal population of the target state.

Structural and Electronic Properties of ConC3-/0 and ConC4-/0 （n=1-4） Clusters： Mass-Selected Anion Photoelectron Spectroscopy and Density Functional Theory Calculations

We investigated the structural evolution and elecfronic properties of ConC3-/0 and ConC4-/0 （n=1-4） clusters by using mass-selected photoelectron spectroscopy and density functional theory calculations. The adiabatic and vertical detachment energies of CO1-4C3- and COl-4C4- were obtained from their photoelectron spectra. By comparing the theoretical results with the experimental data, the global minimum structures were determined. The results indicate that the carbon atoms of ConC3-/0 and ConC4-/0 （n=1-4） are separated from each other gradually with increasing number of cobalt atoms but a C2 unit still remains at n=4. It is interesting that the Co2C3- and Co2C4- anions have planar structures whereas the neutral Co2C3 and Co2C4 have linear structures with the Co atoms at two ends. The Co3C3- anion has a planar structure with a Co2C2 four-membered ring and a Co3C four-membered ring sharing a Co-Co bond, while the neutral Co3C3 is a three-dimensional structure with a C2 unit and a C atom connecting to two faces of the Co3 triangle.

Measurement Induced Enhancement of Squeezing in Nondegenerate Two-Photon Jaynes-Cummings Model

Squeezing properties in the nondegenerate two-photon Jaynes-Cummings model are investigated. The effects of direct selective atomic measurement and the application of the classical field followed by atomic measurement are analyzed. Different values of the parameters of the classical field are taken into account. It is found that the field squeezing can be enhanced by measurement.

基于光子灯笼的模式功率检测方法

为了避免光子灯笼模式解复用器串扰对模式功率测量带来的误差,提出基于单一模式计算方式的波长映射测量方法,详细描述了其工作原理并研制出相应的模式功率检测单元。采用混合模式和单一模式两种计算方式,分析了模式功率检测单元的透射率矩阵特点,实验验证了波长映射测量方法的可行性。实验结果表明,单一模式计算方式对少模光纤的偏振扰动不敏感,其模式透射率的偏振相关性小于0.025。在此基础上搭建了1480 nm前向泵浦的三模掺铒光纤放大器,采用波长映射方法测试了三模同时放大的性能,获得了高达26 dB的模式增益,差模增益小于2 dB。

Effects of nitrogen form on growth,CO_2 assimilation,chlorophyll fluorescence,and photosynthetic electron allocation in cucumber and rice plants

Cucumber and rice plants with varying ammonium (NH4+) sensitivities were used to examine the effects of different nitrogen (N) sources on gas exchange, chlorophyll (Chl) fluorescence quenching, and photosynthetic electron allocation. Compared to nitrate (NO3-)-grown plants, cucumber plants grown under NH4+-nutrition showed decreased plant growth, net photosynthetic rate, stomatal conductance, intercellular carbon dioxide (CO2) level, transpiration rate, maximum photochemical efficiency of photosystem II, and O2-independent alternative electron flux, and increased O2-dependent alternative electron flux. However, the N source had little effect on gas exchange, Chl a fluorescence parameters, and photosynthetic electron allocation in rice plants, except that NH4+-grown plants had a higher O2-independent alternative electron flux than NO3--grown plants. NO3- reduction activity was rarely detected in leaves of NH4+-grown cucumber plants, but was high in NH4+-grown rice plants. These results demonstrate that significant amounts of photosynthetic electron transport were coupled to NO3- assimilation, an effect more significant in NO3-- grown plants than in NH4+-grown plants. Meanwhile, NH4+-tolerant plants exhibited a higher demand for the reduced form of nicotinamide adenine dinucleotide phosphate (NADPH) for NO3- reduction, regardless of the N form supplied, while NH4+-sensitive plants had a high water-water cycle activity when NH4+ was supplied as the sole N source.

Efficient photoelectrochemical CO_(2) conversion for selective acetic acid production

Amidst the development of photoelectrochemical(PEC)CO_(2) conversion toward practical application,the production of high-value chemicals beyond C1 compounds under mild conditions is greatly desired yet challenging.Here,through rational PEC device design by combining Au-loaded and N-doped TiO_(2) plate nanoarray photoanode with Zn-doped Cu_(2)O dark cathode,efficient conversion of CO_(2) to CH3COOH has been achieved with an outstanding Faradaic efficiency up to 58.1%(91.5%carbon selectivity)at 0.5 V vs.Ag/AgCl.Temperature programmed desorption and in situ Raman spectra reveal that the Zn-dopant in Cu_(2)O plays multiple roles in selective catalytic CO_(2) conversion,including local electronic structure manipulation and active site modification,which together promote the formation of intermediate*CH2/*CH3 for C-C coupling.Apart from that,it is also unveiled that the sufficient electron density provided by the Au-loaded and N-doped TiO_(2) plate nanoarray photoanode plays an equally important role by initiating multi-electron CO_(2) reduction.This work provides fresh insights into the PEC system design to reach the multi-electron reduction reaction and facilitate the C-C coupling reaction toward high-value multicarbon(C2+)chemical production via CO_(2) conversion.

High-selective removal of ultra-low level mercury ions from aqueous solution using oligothymonucleic acid functionalized polyethylene film

We prepare oligothymonucleic acid (OTA) functionalized polyethylene (PE) film and evaluate its selective removal ability of mercury ions at ultra-low levels in aqueous solution. The selective binding of OTA with mercury ions is confirmed by fluorescence in situ hybridization (FISH). The quantitative results via cold-vapor atomic fluorescence spectrometry (CVAFS) indicate that OTA-functionalized PE film is able to remove mercury ions at the sub-ppb level selectively from aqueous solution, even with the coexistence of other metal ions at concentrations 250-fold or higher than that of mercury.

A highly selective colorimetric and“Off-On”fluorescence sensor for CN^-based on Zn(salphenazine)complex

The development of sensors for selective detection of cyanide ion(CN^-) is an important mission to accomplish because of the versatility and toxicity of CN^-. In the present work, an "ensemble"-based colorimetric and fluorescent sensor(L2-Zn^(2+)) for CN^-ion has been developed. The addition of cyanide ions removed Zn^(2+) from the ensemble(L2-Zn^(2+)) in aqueous medium, resulting in a color change of the solution from red to buff and a "turn-on" fluorescent response. Also, the sensitivity of both the fluorescenceand colorimetric-based assay is below the maximum allowable level of cyanide ions in drinking water set by the World Health Organization. In addition, test strips, which served as convenient and efficient CN^- test kits, were fabricated based on the sensor.Notably, the selective detection of cyanide with L2-Zn^(2+) for practical application was also performed in sprouting potatoes.