Anharmonic resonance interactions in the bending manifold associated with ν3 in 13C2D2 studied by high—resolution infrared and Raman spectroscopy

The Q branch of the 2ν₂ ← ν₂ band of ¹³C₂D₂ has been recorded with an instrumental resolution of about 0.003 cm^?1 using inverse Raman spectroscopy combined with stimulated Raman pumping in order to populate the ν₂=1 state. A weak local perturbation evident in the spectrum has been attributed to the effect of an anharmonic resonance between the ν₂=2 and ν₃=ν₄=ν₅=1 Σ⁺ _g, states. To study this interaction, the components of the latter vibrational manifold (Σ⁺ _g, ^? _g and Δ_g), together with all the bending states up to (ν₄ + ν₅)=2 associated with ν₃=1, have been characterized through the analysis of their infrared spectra. Both cold and hot bands from states thermally populated at room temperature, ν₄, ν₅, 2ν₄, 2ν₅ and ν₄ + ν₅, have been recorded in the region between 2300 and 3000 cm^?1 at an effective resolution of about 0.009 cm^?1. A simultaneous analysis of all the assigned transitions has been performed on the basis of a theoretical model which takes into account the rotational and vibrational ?-type resonances within each vibrational manifold, the Darling-Dennison anharmonic resonance between the ν₃ + 2ν₄ and ν₃ + 2ν₅ states, and the anharmonic interaction between the 2ν₂ and ν₃ + ν₄ + ν₅ states.     

Density field theory for a fluid interacting with the Yukawa potential. Role of the ideal entropy

We present a field theory to describe liquids where the field represents the density. In terms of this field, the Hamiltonian contains the ideal entropy and the interaction between the density fields. The approach is illustrated with the Yukawa interaction and presented in the grand canonical ensemble formalism. In this framework, first, we derive a relation specific to the field theory. This relation is equivalent to the ‘equation of motion’ in field theory for interacting quantum particles. Then, focusing on the effect of the fluctuations, we calculate thermodynamic quantities beyond the mean field. The pressure, the density and the compressibility at a given chemical potential in the quadratic approximation and beyond are given. The aim of this paper is to illustrate the importance and the role of the ideal entropy in this type of approach. The density and the compressibility at a given chemical potential are calculated perturbatively in various ways. Whether from their field theoretical definition, or deriving them from one another using the thermodynamical relations or also using the ‘equation of motion’, the results are in all ways of calculation consistent. However, the different calculations require different levels of expansion of the ideal entropy term involving in our case three and four body coupling constants. The consistency is then closely related to the form of the functional of the ideal entropy.     

The ν6, ν8 3ν4+ν12 infrared system of Si2H6 under high resolution: rotational and torsional analysis

A Fourier transform infrared spectrum of disilane has been measured at a Doppler limited resolution, and analysed in the region of the ν₆ and ν₈ fundamentals, from about 800 to 1020cm^?1. The torsional splittings are not resolved in the ν₆ band, showing that the splittings in the ν₆ = 1 state and in the ground state are almost identical. The torsional splittings in the reasonably unperturbed regions of the ν₈ fundamental are about 0.0146cm^?1, and a detailed rotation-torsion analysis shows that the intrinsic splittings in the ν₈ = 1 state are smaller than in the ground state by this amount. An intrinsic torsional splitting about 0.0150 cm^?1 is estimated in the vibrational ground state and in the ν₆ = 1 state, and almost vanishing in the ν₈ = 1 state (about 0.0004cm^?1), with a barrier height around 407cm^?1. This is in agreement with the expectation from theory. The ν₈ band, beyond a moderate x, y-Coriolis coupling with ν₆, is affected by several perturbations, also selective in the torsional components. The 3ν₄ + v¹² combination, with three quanta of the torsional mode excited and large torsional splittings, is the main perturber, causing both Fermi and Coriolis resonances in several regions of the spectrum. The vibrational origins of all four torsional components of 3ν₄ + v¹² were determined. Other perturbative effects are attributed to the systems 2ν₃ + ν₄, and ν₄ + 24₉(E + A). The spectrum was numerically analysed, and the relevant vibration-rotation-torsion parameters were determined.     

The stretching fundamental bands of 13C2D2

The stretching fundamental bands of the isotopically substituted acetylene ¹³C₂D₂ have been recorded and analysed. The Raman spectra of the Q branch of v ₁ and v ₂, Σ⁺ _g -Σ⁺ _g bands, have been recorded with an instrumental resolution of about 3.0 x 10^?3 cm^?1 using inverse Raman spectroscopy. The infrared spectrum has been recorded in the region between 2350 cm^?1 and 2500 cm^?1 with an instrumental resolution of 4.0 x 10^?3 cm^?1. Transitions belonging to the v ₃, Σ⁺ _u -Σ⁺ _g , fundamental band have been identified and assigned. The vibrational energies and the rotational and centrifugal distortion constants of the excited states of all the observed transitions have been determined. The molecular parameters obtained reproduce the assigned wave-numbers with a standard deviation of the same order of magnitude as the experimental uncertainty.     

NaYF4:Er3+,Yb3+UCNPs为供体的均相荧光分析

在基于荧光共振能量传递(FRET)的均相分析中,小尺寸的上转换发光纳米晶(UCNPs)用作供体被认为有很大的优势。通过配体交换的方式制备了大小约12nm、表面带有氨基的水溶性NaYF4∶Er3+,Yb3+UCNPs。傅里叶变换红外光谱证明配体交换成功;扫描电镜表明UCNPs的形貌和尺寸没有改变;圆二色光谱表征亲合素偶联UCNPs前后二级结构变化较小。以亲合素化的NaYF4∶Er3+,Yb3+UCNPs为供体;受体为生物素标记的藻红蛋白。通过亲合素—生物素系统拉近供体和受体,引发共振能量传递。当体系中加入自由的生物素分子,它们竞争地与UCNPs表面的亲合素结合,抑制能量传递过程,从而荧光光谱发生变化。根据这种光谱变化与加入生物素量之间的关系,对其进行定量检测,获得了纳摩尔级的检测限。     

非等谱散焦非线性Schrdinger方程的规范变换和精确解

非线性Schrdinger方程及其相关方程在许多领域都得到广泛应用.为了研究谱参数随时间变化时散焦非线性Schrdinger方程的性质,研究了三个非等谱散焦非线性Schrdinger方程.对于前两个方程,给出了它们与等谱方程之间的规范变换,以及多孤子精确解.对于第三个方程给出了单孤子解.     

Data processing for image-based chemical sensors: unsupervised region of interest selection and background noise compensation

Natural olfaction suggests that numerous replicas of small sensors can achieve large sensitivity. This concept of sensor redundancy can be exploited by use of optical chemical sensors whose use of image sensors enables the simultaneous measurement of several spatially distributed indicators. Digital image sensors split the framed scene into hundreds of thousands of pixels each corresponding to a portion of the sensing layer. The signal from each pixel can be regarded as an independent sensor, which leads to a highly redundant sensor array. Such redundancy can eventually be exploited to increase the signal-to-noise ratio. In this paper we report an algorithm for reduction of the noise of pixel signals. For this purpose, the algorithm processes the output of groups of pixels whose signals share the same time behavior, as is the case for signals related to the same indicator. To define these groups of pixels, unsupervised clustering, based on classification of the indicator colors, is proposed here. This approach to signal processing is tested in experiments on the chemical sensitivity of replicas of eight indicators spotted on to a plastic substrate. Results show that the groups of pixels can be defined independently of the geometrical arrangement of the sensing spots, and substantial improvement of the signal-to-noise ratio is obtained, enabling the detection of volatile compounds at any location on the distributed sensing layer.     

配位聚合物{[Mn（H2BCPBA）2（H2O）4]}n的合成和表征

采用3,5-bi(4-carboxy-phenoxy)-benzoic acid(H3BCPBA)为配体,以Mn为中心离子采用自组装的方法合成了配位聚合物{[Mn(H2BCPBA)2(H2O)4]}n,采用单晶衍射仪,红外光谱,热重,固体紫外和元素分析对其进行了晶体结构的解析和表征。它属于三斜晶系,P1空间群,晶胞参数分别为a=0.58423(13)nm,b=1.3644(3)nm,c=1.3910(3)nm,α=109.173(2)°,β=98.927(3)°,γ=99.123(3)°,V=1.0082(4)nm,Mr=913.63,Z=1,Dc=1.505 g/cm3,μ=0.414 mm-1,F(000)=471.0。热重分析表明,该配合物在410℃下稳定,UV固体光谱表明,该配合物有很弱的吸收。     

配位聚合物{[Co3(TCOPM)2(H2O)2]·17H2O}n的合成和结构

采用三(对-苯甲酸)甲烷(H3TCOPM)为配体,以Co为中心离子采用自组装的方法合成了配位聚合物{[Co3(TCOPM)2(H2O)2]·17H2O}n,利用单晶衍射仪,红外光谱,TG和元素分析对其进行了晶体结构的解析和表征.它属于单斜晶系,C2/c空间群,晶胞参数分别为a=2.9675(13) nm,b =1.3548(5) nm,c=1.8659 (5) nm,α=90.00°,β=124.61(2)°,γ=90.00°,V=6.174(4) nm3,Mr=959.47,Z=4,Dc=1.187 g/cm3,μ =0.860 mm-1,F(000)=2268.0.结果表明,配位聚合物中H3TCOPM的三个羧酸全部和Co配位,形成三维结构,展现了一个具有tfd连接拓扑网络结构,其孔隙率为47.6;.     

基于银纳米颗粒的PCF SERS传感器优化设计

为充分发挥表面增强拉曼散射(SERS)光子晶体光纤(PCF)传感器的应用价值,对实芯PCF的结构、银纳米颗粒结构参数对传感性能的影响进行研究与对比,据此设计出适用于PCFSERS传感的实芯PCF以及银纳米颗粒的形状、大小、间距等参数.经数值计算,入射波长为785 nm时,设计的实芯六孔PCF模场面积可达25.8 μm2,并能够实现单模传输.而半径为38 nm的银纳米球,间距为0.7nm时能够产生最大的SERS增强因子.研究证明,设计的实芯PCF在785 nm输入波长下能够提供理想的活性面积,银纳米颗粒的形状、尺寸、间距对SERS性能影响严重,而且与入射波长有很强的依赖关系.