Fabrication and performance of MMW and SMMW platelet horn arrays

Future spaceborne millimeter and sub-millimeter wave sensing systems will require the sensitivity and resolution only achievable with large focal plane array receiving systems. A technique has been developed for the low cost fabrication of large arrays of millimeter and sub-millimeter wave corrugated feed horns. These arrayed horns exhibit high efficiency and symmetrical receiving patterns and are compatible with integrated receivers. W-band test results of a 3×3 array are presented.     

国外长波红外焦平面列阵现状

文中介绍了长波工外焦平面列阵的国外进展，这些列阵包括碲镉汞光电二极管、肖特基势垒器件、砷化镓／砷铝镓多量子阱光导体、高温超导体以及室温工作的焦平面列阵，其中非制冷的混合式热释电陶瓷和单片式的微型测辐射热计焦平面列阵已进入批理生产阶段。     

Study on Infrared Transmission Spectrum of Sildenafil Citrate Mixed in Traditional Chinese Medicine

The infrared transmission spectrum has been studied on the mixed medicine sample composed of sildenafil citrate (SDF or Viagra) and traditional Chinese medicine(TCM). The measured infrared spectra are composed of several broad absorption bands and many sharp absorption lines. Then the broad absorption bands are changed from sample to sample. It is identified that the sharp and broad absorption bands are from the Viagra and TCM, respectively. A numerical best fitting process has been used to extract the absorption spectrum from the spectrum of mixed sample. Combined with the numerical analysis, the Viagra component can be extracted from the mixed material even with a changeable broad absorption bands' background. It shows that the infrared transmission spectroscopy is a useful method to extract the component of chemical medicine from the mixed medicine.     

蛋白质分子的红外吸收的温度特征

考虑了Ａｍｉｄｅ－Ⅰ振子同肽群振动的光学声子相耦合，在该理论中研究了在蛋白质分子中的孤立子引起的红外吸收的反常红移和温度依赖关系。所得结果较好地吻合于实验值。从而也证实了蛋白质中确有孤立子激发的存在     

The eight first vibrational states of the water molecule: measurements and analysis

In this work the spectrum of the water molecule has been the subject of extensive experimental and theoretical investigations. More than 1500 transitions have been assigned in a far infrared emission spectrum recorded in the 50-500 cm⁻¹ region and experimental rotational energies have been obtained for the second triad of interacting states, (0 3 0), (1 1 0), and (0 1 1), up to J=10 using flame spectroscopy. These new data along with a large data set of already published experimental rotational energies, high-resolution infrared transitions, and microwave lines, involving the eight first vibrational states, have been analyzed using the theoretical formalism developed for water in a previous paper (J. Mol. Spectrosc. 206 (2001) 83), which accounts for the anomalous centrifugal distortion as well as for the Fermi- and Coriolis-type couplings.     

低温低噪声红外前置放大器的计算机辅助设

通过ＰＳＰＩＣＥ５．０的模型参数提取工具ＰＡＲＴＳ软件，提取并确定了低温低频低噪声双极晶体管的器件模型参数，利用ＰＳＰＩＣＥ５．０对低温红外前置放大器进行了计算机辅助设计和优化，成功地对双极模拟电路进行了温度为１２０Ｋ（—１５３℃）的多种模拟分析。采用ＭＣＭ技术制作出了混合集成低温红外前置放大器，实际电路的ＣＡＴ测试结果与计算机辅助设计结果相吻合。     

Metalorganic chemical vapor deposition of HgCdTe for photodiode applications

Metalorganic chemical vapor depositon (MOCVD) in situ growth of p-on-n junctions for long wavelength infrared (LWIR) and medium wavelength infrared (MWIR) photodiodes is reported. The interdiffused multilayer process was used for the growth of the HgCdTe junctions on CdTe and CdZnTe substrates. The n-type region was grown undoped while the p-type layer was arsenic doped using tertiarybutylarsine. Following a low temperature anneal in Hg vapor, carrier densities of (0.2-2) x 10¹⁵ cm³ and mobilities of (0.7-1.2) x 10⁵ cm²/V-s were obtained for n-type LWIR (x ~ 0.22) layers at 80K. Carrier lifetimes of these layers at 80 K are ~l-2 μs. For the p-type region arsenic doping was controlled in the range of (1-20) x 10¹⁶ cm^-3. Arsenic doping levels in the junctions were determined by calibrated secondary ion mass spectroscopy depth profile measurements. Composition and doping of the p-on-n heterojunctions could be independently controlled so that the electrical junction could be located deeper than the change in the composition. The graded composition region between the narrow and wide (x = 0.28-0.30) bandgap regions are 1–2 μm depending on the growth temperature. Backside-illuminated variable-area circular mesa photodiode arrays were fabricated on the grown junctions as well as on ion implanted n-on-p MWIR junctions. The spectral responses are classical in shape. Quantum efficiencies at 80K are 42–77% for devices without anti-reflection coating and with cutoff wavelengths of 4.8–11.0 μm. Quantum efficiencies are independent of reverse bias voltage and do not decrease strongly at lower temperatures indicating that valence band barrier effects are not present. 80K R_oA of 15.9 Ω-cm² was obtained for an array with 11.0 μm cutoff. Detailed measurements of the characteristics of the MOCVD in situ grown and implanted photodiodes are reported.     

Direct growth of CdZnTe/Si substrates for large-area HgCdTe infrared focal plane arrays

Direct epitaxial growth of high-quality 100lCdZnTe on 3 inch diameter vicinal {100}Si substrates has been achieved using molecular beam epitaxy (MBE); a ZnTe initial layer was used to maintain the {100} Si substrate orientation. The properties of these substrates and associated HgCdTe layers grown by liquid phase epitaxy (LPE) and subsequently processed long wavelength infrared (LWIR) detectors were compared directly with our related efforts using CdZnTe/ GaAs/Si substrates grown by metalorganic chemical vapor deposition (MOCVD). The MBE-grown CdZnTe layers are highly specular and have both excellent thickness and compositional uniformity. The x-ray full-width at half-maximum (FWHM) of the MBE-grown CdZnTe/Si increases with composition, which is a characteristic of CdZnTe grown by vapor phase epitaxy, and is essentially equivalent to our results obtained on CdZnTe/GaAs/Si. As we have previously observed, the x-ray FWHM of LPE-grown HgCdTe decreases, particularly for CdZnTe compositions near the lattice matching condition to HgCdTe; so far the best value we have achieved is 54 arc-s. Using these MBE-grown substrates, we have fabricated the first high-performance LWIR HgCdTe detectors and 256 x 256 arrays using substrates consisting of CdZnTe grown directly on Si without the use of an intermediate GaAs buffer layer. We find first that there is no significant difference between arrays fabricated on either CdZnTe/Si or CdZnTe/GaAs/Si and second that the results on these Si-based substrates are comparable with results on bulk CdZnTe substrates at 78K. Further improvements in detector performance on Si-based substrates require a decrease in the dislocation density.     

Unimodularity of the Clar number problem

We study the generalization to bipartite and 2-connected plane graphs of the Clar number, an optimization model proposed by Clar [E. Clar, The Aromatic Sextet, John Wiley & Sons, London, 1972] to compute indices of benzenoid hydrocarbons. Hansen and Zheng [P. Hansen, M. Zheng, The Clar number of a benzenoid hydrocarbon and linear programming, J. Math. Chem. 15 (1994) 93–107] formulated the Clar problem as an integer program and conjectured that solving the linear programming relaxation always yields integral solutions. We establish their conjecture by proving that the constraint matrix of the Clar integer program is always unimodular. Interestingly, in general these matrices are not totally unimodular. Similar results hold for the Fries number, an alternative index for benzenoids proposed earlier by Fries [K. Fries, Uber Byclische Verbindungen und ihren Vergleich mit dem Naphtalin, Ann. Chem. 454 (1927) 121–324].     

红外区表面电磁波（IRSEW）技术

本文简要介绍了表面电磁波(Surface Electromagnetic Waves,简称SEW)的基本原理,红外表面电磁波的产生方法,它在光滑金属表面的传播及表面状况对传播长度的影响,最后指出它在表面无损检测中应用的可能性及前景。