MoⅩⅣ—RuⅩⅥ离子的3d104s—3d94s4p跃迁谱线波长和振子强度的计算

在对GeⅣ—RuⅩⅥ离子3d-94s4p组态能级结构的组态相互作用理论分析计算的基础上，进一步分析了关联效应，量子电动力学（QED）效应及其他效应对等电子序列离子能级结构的影响，找出了沿等电子序列离子能级变化的规律性.在前人研究工作的基础上，预测计算了MoⅩⅣ—RuⅩⅥ离子3d-94s4pJ=12,32组态能级，由此计算了MoⅩⅣ—RuⅩⅥ离子3d-104s—3d-94s4pJ=12,32跃迁谱线波长，振子强度和跃迁概率. 关键词： GeⅣ—RuⅩⅥ离子 谱线波长 振子强度 跃迁概率     

Microwave study of the submillimeter spectrum of the H2O?HF dimer

The study of the rotational spectrum of the H₂O?HF dimer in the equilibrium gas phase in the range 180-350 GHz by continuously frequency scanning microwave spectrometer with backward-wave oscillator and acoustic detection of absorption is described. The results of analyzing of the most intense spectral series are given. The assignment of some spectral series observed earlier is corrected. Data on the Coriolis interaction between the ground and excited vibrational states are obtained and spectroscopic constants of the dimer are significantly refined.     

双波长剩余小数法标定光学劈尖厚度及其约束条件研究

本文提出了利用双波长标定光学劈尖厚度的剩余小数法,详细研究了该方法所应满足的约束条件,并给出了实验结果。     

A 400–500 GHz Balanced SIS Mixer with a Waveguide Quadrature Hybrid Coupler

We have developed a 400–500 GHz low-noise balanced SIS (Superconductor Insulator Superconductor) mixer, which is based on a waveguide RF quadrature hybrid coupler. The RF quadrature hybrid was designed and fabricated as a broadband hybrid with good performance at 4 K. The fabricated RF quadrature hybrid was measured at room temperature with a submillimeter vector network analyzer to check amplitude and phase imbalance between two output ports. Then the balanced mixer was assembled with the RF hybrid, two DSB mixers, and a 180° IF hybrid. Several important parameters such as noise temperature, LO power reduction, and IF spectra were measured. The LO power reduction is defined as how much LO power the balanced mixer saves compared with a typical single-ended mixer. The measured noise temperature of the balanced mixer was ~ 55 K at the band center which corresponds to ~ 3 times the quantum noise limit (hf/k) in DSB, and ~ 120 K at the band edges. The noise performance over LO frequency was almost the same as that of the worse DSB mixer used in the balanced mixer. In addition the LO power required for the balanced mixer is ~ 11 dB less than that of the single-ended mixers.     

高光谱技术结合特征波长/光谱指数对冬枣成熟度可视化判别

为了给冬枣采收后成熟度分级提供理论指导,运用高光谱技术获取特征波长和计算光谱指数对其成熟度可视化分级。采集三类成熟度冬枣(未成熟果、白熟-初红果、半红-全红果)样本共336个并获取其高光谱信息,通过Savitzky-Golay(S-G)平滑对原始光谱降噪后再用Kennard-Stone(K-S)方法将样本分为训练集(226个)和测试集(110个)。选用连续投影法(SPA)和竞争性自适应重加权采样法(CARS)选择特征波长(CWs);同时从水果生理成分变化角度引入7个光谱指数(SIs)。基于SPA和CARS选取的CWs和引入的SIs分别建立偏最小二乘判别分析(PLS-DA)模型,并比较了3个模型的分级效果。结果表明：基于SPA和CARS选择的特征波长和引入的SIs建立的PLS-DA模型判别精度分别为：97.27%,95.45%和98.18%。为了直观展现判别结果,选用SIs建立的PLS-DA回归系数拟合判别向量Y的回归方程,依据Y中最大值元素所在类别为该样本预测类别的规则,将结果用不同颜色直观显示。该研究为冬枣成熟度可视化分级提供了思路,引入的SIs参数为开发适于多种水果成熟度分级的设备提供了技术支撑。     

A millimeter and sub-millimeter wave frequency selective surface beamsplitter for geostationary orbit microwave radiometers

We report the design of three frequency selective surface(FSS) filters used on the FengYun-4(FY-4) microwave satellite,which separate five-frequency bands in the frequency range of 50-429 GHz with the insertion loss less than 0.4 dB,and separation between adjacent channels more than 20 dB for either TE or TM incidence.Firstly,we briefly introduce the disadvantages of two types of FSS filter:waveguide-array FSS and printed FSS,which are commonly employed in the millimeter and sub-millimeter wave band.In order to meet the insertion loss requirement and specified spectral transmission response,we adopt a filter composed of two closely spaced freestanding metal plates,which contains an array of resonant ring slot elements.Computer simulation technology(CST) is used to optimize the structural dimensions of the resonant unit and interlayer separation.Numerical results show that these FSS filters exhibit transmission loss of less than 0.4 dB and separation between adjacent channels of more than 20 dB.Simulated transmission coefficients are in close agreement with the required specification,and even exceed the performance specifications.     

Spatiotemporal propagation dynamics of intense optical pulses in loosely confined gas-filled hollow-core fibers

We numerically study the propagation dynamics of intense optical pulses in gas-filled hollow-core fibers(HCFs). The spatiotemporal dynamics of the pulses show a transition from tightly confined to loosely confined characteristics as the fiber core is increased, which manifests as a deterioration in the spatiotemporal uniformity of the beam. It is found that using the gas pressure gradient does not enhance the beam quality in large-core HCFs, while inducing a positive chirp in the pulse to lower the peak power can improve the beam quality. This indicates that the self-focusing effect in the HCFs is the main driving force for the propagation dynamics. It also suggests that pulses at longer wavelengths are more suitable for HCFs with large cores because of the lower critical power of self-focusing, which is justified by the numerical simulations. These results will benefit the generation of energetic few-cycle pulses in large-core HCFs.     

Transition wavelengths for helium atom in weakly coupled hot plasmas

We have investigated the effect of surrounding plasmas on several singly excited and doubly excited meta-stable bound states of helium atom using highly correlated basis functions for singly excited S, P, D states and CI-type basis functions for doubly excited meta-stable D states. Plasma effect is taken care of by using a screened Coulomb (Yukawa) potential obtained from the Debye model that admits a variety of plasma conditions, and such a model plays an important role in plasma spectroscopy. The wavelengths for transitions from the 1snp ¹P° (n=2,3)→1s²¹S^e, 1snp ³P° (n=2,3)→1s2s ³S^e, 2pnp ¹P^e (n=3,4)→1s2p ¹P°, 2pnp ³P^e (n=2,3)→1s2p ³P°, 2pnd ¹D° (n=3,4)→1s3d ¹D^e, 2pnd ³D° (n=3,4)→1s3d ³D^e, 2p3p ¹P^e→2pnd ¹D° (n=3,4), 2pnd ¹D°(n=3, 4)→2p4p ¹P^e, 2pnp ³P^e (n=2,3)→2p3d ³D°, and 2pnp ³P^e (n=2,3)→2p4d ³D° of helium atom in plasmas for various Debye lengths are reported.     

Theoretical performance of novel multipliers at millimeter and submillimeter wavelengths

A theoretical comparison of various low and high order multipliers for 200 GHz and 1 THz has been carried out. Novel diodes including single barrier varactors, barrier-intrinsic-n⁺ diodes and high electron mobility varactors are shown to have excellent theoretical performance, comparable or better than the conventional Schottky varactors for single and double diode frequency multipliers at millimeter and submillimeter wavelengths, whereas quantum well diodes, since they suffer from high resistive losses, are shown to be less attractive. In comparison to the conventional Schottky varactor, these new diodes have some potential advantages in their characteristics such as nonlinearity or a special symmetry. For future optimization some general comments on these advantages as well as other factors affecting multiplication is given.     

The pure rotational spectrum of TiS (XΔr) at submillimeter wavelengths

The pure rotational spectrum of TiS in its X³Δ_r ground state has been measured using millimeter-wave direct-absorption techniques in the frequency range of 313-425 GHz. This free radical was created by the reaction of titanium vapor, produced in a high-temperature Broida-type oven, with H₂S. Eight to ten rotational transitions were recorded for the main titanium isotopologue, ⁴⁸TiS, in the v = 0 and v = 1 levels, as well as for the v = 0 state of ⁴⁶TiS, observed in natural abundance (⁴⁸Ti:⁴⁶Ti = 74:8). All three Ω components were observed in almost every recorded transition, with no evidence for lambda-doubling. The data were fit with a Hund’s case(a) Hamiltonian, and rotational, spin-orbit, and spin-spin constants were determined, as well as equilibrium parameters for ⁴⁸TiS. Relatively few fine structure parameters were needed for the analysis of TiS (A, A_D, and λ), unlike other 3d metal species. The rotational pattern of the three fine structure components suggests the presence of a nearby excited ¹Δ state, lying ∼3000 cm⁻¹ higher in energy. From the equilibrium parameters, the dissociation energy for TiS was estimated to be ∼5.1 eV, in reasonable agreement with past thermochemical data.