InAs/GaSb superlattice focal plane arrays for high-resolution thermal imaging

The first fully operational mid-IR (3–5 μm) 256×256 IR-FPA camera system based on a type-II InAs/GaSb short-period superlattice showing an excellent noise equivalent temperature difference below 10 mK and a very uniform performance has been realized. We report on the development and fabrication of the detecor chip, i.e., epitaxy, processing technology and electro-optical characterization of fully integrated InAs/GaSb superlattice focal plane arrays. While the superlattice design employed for the first demonstrator camera yielded a quantum efficiency around 30%, a superlattice structure grown with a thicker active layer and an optimized V/III BEP ratio during growth of the InAs layers exhibits a significant increase in quantum efficiency. Quantitative responsivity measurements reveal a quantum efficiency of about 60% for InAs/GaSb superlattice focal plane arrays after implementing this design improvement. The paper presented there appears in Infrared Photoelectronics, edited by Antoni Rogalski, Eustace L. Dereniak, Fiodor F. Sizov, Proc. SPIE Vol. 5957, 595707 (2005).     

Structural anisotropy in friction‐deposited layers of polystyrene

Friction‐deposited layers of atactic polystyrene (PS) on inert and OH‐grafted gold substrates were the subject of this study to establish a relationship between the friction process and the resulting anisotropy of the transferred polymer chains. We show, by using polarization‐modulation infrared reflection‐absorption spectroscopy that the deposited PS chains involve an anisotropy in which PS main backbone is rather perpendicular to the friction support, fact that is surprising when compared with the majority of polymers where the anisotropy is along the sliding direction. Moreover, our calculation of the orientation angles revealed that PS chains are more perpendicular in the transferred layers than in spin‐coated films. This particular anisotropy is probably due to a parallel reorientation of the phenyl ring on the friction support whatever the surface chemistry is. On the other hand, this study was useful to rectify the assignment of infrared bands unclearly reported in the literature. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 3272–3281, 2006     

Asymptotic behavior of energy band associated with a negative energy level

The mathematical foundation of the tight binding approximation is given. If ₀ is a negative energy level of a real potentialq, then there exists an energy band for a one-dimensional chain with period 2T of the same atoms which lies near ₀. We study this band whenT tends to infinity.On leave of absence from the Department of Physics, Leningrad State University, Leningrad, USSR.     

Study of the spectrum of CH335C1 between 4250 and 4600 CM?1: thev2+v4 andv4+v5 rovibrational bands

About 2500 lines of CH₃ ³⁵Cl have been assigned. The strong xy Coriolis resonance between thev ₂ andv ₅ modes is quite visible between thev ₄+v ₄ ^±1 perpendicular band, centered around 4383 cm^–1, and thev ₄ ^±1 +v ₅ ^±1 perpendicular component, centered around 4475 cm^–1, with a crossing of upper energy levels allowing the observation of lines which are normally forbidden. Although not yet observed with certainty, because of the great density of lines of the spectrum, thev ₄ ¹ +v ₅ ^±1 parallel component is nevertheless detectable by its effects onv ₂+v ₄ ^±1 which is linked by Coriolis resonance to both components ofv ₄+v ₅. Moreover the spectrum is much complicated by many other resonances with weak bands which occur at level crossings: it is the case ofv ₂+3v ₆ ^±1 , connected tov ₂+v ₄ ^±1 by the well known Darling Dennison resonance which couplesv ₄ ^±1 and 3v ₆ ^±1 , and also ofv ₅ ^±1 +3v ₆ ^±1 connected tov ₄ ^±1 +v ₅ ^±1 by the same resonance; but this last case is complicated by an anharmonic resonance betweenv ₅ ^±1 +3v ₆ ^±1 and 2v ₃+3v ₆ ¹ . Two more perturbations occur on the K=–1 side ofv ₂+v ₄: a weak Coriolis resonance gives rise to one subband ofv ₁+v ₂ at a level crossing withv ₂+v ₄, and thev ₁+v ₅ band (linked of course tov ₁+v ₂ by the Coriolis resonance between thev ₂ andv ₅ modes) is quite visible and perturbs several subbands ofv ₂+v ₄ of high values of K through an anharmonic resonance. Moreover, the complex (3v ₅ ^±1 ,v+2v ₅ ⁰ , 2v ₂+v ₅ ^±1 , 3v ₂,v ₂+2v ₅ ^±2 , 3v ₅ ^±3 ) system of Coriolis-connected bands is linked to the bands studied in the present work by two Fermi resonances: one betweenv ₂+2v ₅ ⁰ andv ₁+v ₂, and the other one betweenv ₁+v ₅ and 3v ₅ ^±1 , whose several subbands have been observed on the low part of the spectrum. The values of all the band centres and of the different coupling constants have been estimated, but all these interactions make the line assignments and the interpretation of the spectrum very difficult.     

聚乙烯单晶的退火效应

用混合晶红外光谱法和ＳＡＸＳ、ＤＳＣ和ＬＡＭ等方法研究了聚乙烯单晶在７５℃、９０℃和１０５℃退火前后的结构变化，发现在９０℃以下和１０５℃以上退火，遵循不同的退火机制     

付里叶变换红外光谱仪的操作参数对光谱的影响

本文以二苯基甲酮的ＫＢｒ压片为标样，在Ｂｒｕｋｅｒ ＩＦＳ １２０ＨＲ付里叶变换红外光谱仪上系统考察了该仪器折一些重要操作参数（光源光栏、切趾函数、扫描速度）对光谱质量（信噪比，分辨率）的影响。从而获得了测样时的优化操作条件。     

FTS-20E富里叶红外光谱仪数据系统改造

报道了ＦＴＳ－２０Ｆ富里叶红外光谱仪数据系统改造的工作采用ＩＢＭ４８６计算机及新的数据接口取代了陈旧的ＮＯＶＡ４数据系统，文章详细描述了其硬件设计和软件编辑，改造不仅更新了ＦＴＳ－２０Ｅ里叶红外光谱仪，而且还使其达到９０年代的水平。     

Conformations, Energy and Spectral Characteristics of 2,3-Trimethylene- and 2,3-Pentamethylene-3,4-dihydro-4-quinazolinones

Quantum-chemical calculations and IR spectroscopy were used to study the conformations as well as the energy and spectral characteristics of 2,3-trimethylene- and 2,3-pentamethylene-3,4-dihydro-4-quinazolinones. The shift of -electron density from the heterocyclic system to the carbonyl group and, thus, the proton affinity of the oxygen atom of this group increase with expansion of the bond angle at the nitrogen atom in going from a five-membered to seven-membered ring.     

Thermal Stability Of Folic Acid in the solid-state

This study attempts to identify the degradative process which folic acid undergoes in the solid-state under thermal stress. In order to facilitate the process, the various pieces of the chemical structure, namely, p-amino benzoic acid, pterin and glutamic acid as both its d- and l-isomers were investigated as separate entities. These structured solid-state pieces were then compared to the composite solid state folic acid degradative curves in order to identify the peaks seen and provide direction for the interpolation of the degradative mechanism. It was observed that none of the structural pieces could be superimposed as assumed earlier and hence an attempt was made to identify the decomposition products using various analytical techniques such as infrared spectroscopy, mass spectroscopy and X-ray diffraction which suggested that the glutamic acid fragment is lost first as evidenced by acid loss and amide enhancement in the IR spectra. The vitamin was ultimately degrading to carbon fragments and that further identification was not necessary. This revised version was published online in August 2006 with corrections to the Cover Date.     

傅立叶变换红外光谱对灰指甲组织结构的研究

对健康指甲和灰指甲的红外光谱特征吸收峰进行了指认,并对其相应官能团的吸收峰进行了对比分析.结果表明,灰指甲增厚、变脆的原因系α-角蛋白螺旋结构遭到破坏,肽链伸展并发生断裂,形成了不同化学环境的氨基酸,同时蛋白质分子的有序排列也发生了改变.