80th anniversary of Anatoly M. Kharitonov

Anniversary Dates

80th anniversary of Anatoly M. Kharitonov     

High-resolution FTIR spectrum of vinyl chloride: rovibrational analysis of the v 10 and v 11 fundamental bands

The Fourier transform gas-phase infrared spectra of the v ₁₀ and v ₁₁ bands of natural CH₂=CHCl have been measured with a resolution of 0.005 cm^?1 in the frequency range 820–1010 cm^?1. These vibrations of symmetry species A″ give rise to c-type bands and the transitions observed are characterized by δK _a = ±1 and δK _c = 0, ±2. Both J and K structures have been resolved in different subbranches and about 1800 (J ≤ 64, K _a ≤ 13) and 2800 (J ≤ 72, K _a ≤ 14) transitions for the v ₁₀ and v ₁₁ fundamentals, respectively, have been identified for the ³⁵Cl isotopomer. Combined analysis of the assigned data with the available ground state constants allowed the determination of the band origins, rotational and centrifugal distortion parameters for the v ₁₀ = 1 and v ₁₁ = 1 excited states of CH₂=CH³⁵Cl isotopic species. The molecular constants obtained account for slight perturbations in the v ₁₀ vibrational level.     

Direct correlation functions and bridge functions in additive hard-sphere mixtures

A method to obtain (approximate) analytical expressions for the radial distribution functions in a multicomponent mixture of additive hard spheres that was recently introduced is used to obtain the direct correlation functions and bridge functions in these systems. This method, which yields results practically equivalent to the generalized mean spherical approximation and includes thermodynamic consistency, is an alternative to the usual integral equation approaches and requires as input only the contact values of the radial distribution functions and the isothermal compressibility. Calculations of the bridge functions for a binary mixture using the Boublik-Mansoori-Carnahan-Starling-Leland equation of state are compared to parallel results obtained from the solution of the Percus-Yevick equation. We find that the conjecture recently proposed by Guzman and del Rio (1998, 98, Molec. Phys., 95, 645), stating that the zeros of the bridge functions occur approximately at the same value of the shifted distance for all pairs of interactions, is at odds with our results. Moreover, in the case of disparate sizes, even the Percus-Yevick bridge functions do not have this property. It is also found that the bridge functions are not necessarily non-positive.     

Dynamics on reactive potential energy surfaces: hyperspherical view and signatures of ‘quantum chaos’

Adiabatic energy levels for two prototypical reactions, F + H₂ → HF + H and He + H⁺ ₂ → HeH⁺ + H, are analysed by means of statistical tests. These levels result from quantum mechanical calculations of dynamics based on the hyperspherical approach, and are given as a function of the total inertia of the system measured by the hyperradius ρ The nearest neighbour level spacing distributions of Brody and of Berry and Robnik, the spectral rigidity δ₃ of Dyson and Mehta and the correlation coefficient are reported, together with other properties, such as variance, skewness and kurtosis of the distributions. Trends are studied as a function of ρ, proposed as a natural control variable. For low ρ, which correspond to the transition state, evidence is found of Wigner-like behaviour, which is interpreted as the signature of quantum chaos. On the passage of the systems through intermediate ρ a mixture of Wigner- and Poisson-like behaviour emerges. The situation for high ρ where reactants and products of the reactions are well separated, is characterized by a tendency towards regular Poisson-like behaviour. A comparison between the two investigated systems shows that the chaotic regime in the transition state region is more pronounced for the He reaction, which proceeds through a deep well and whose dynamics are characterized by a rich resonance pattern.     

香菇多糖L-2A的结构表征

从香菇子实体中提取纯化得到香菇多糖级分L-2A,利用紫外光谱、红外光谱、凝胶渗透色谱和气相色谱分析其结构特征.香菇多糖L-2A糖含量为90.14%;重均分子量是2.03×10 5道尔顿;具有D-葡萄吡喃糖构型,单糖组成主要是由吡喃型葡萄糖组成;香菇多糖L-2A多糖含有o-糖苷键,且主要是o-Ser连接方式;具有与刚果红结合的螺旋结构.香菇多糖L-2A为首次从香菇子实体中分离得到.     

Optical characterization of InxGa1−xN alloys

InGaN layers were grown by molecular beam epitaxy (MBE) either directly on (0 0 0 1) sapphire substrates or on GaN-template layers deposited by metal-organic vapor-phase epitaxy (MOVPE). We combined spectroscopic ellipsometry (SE), Raman spectroscopy (RS), photoluminescence (PL) and atomic force microscopy (AFM) measurements to investigate optical properties, microstructure, vibrational and mechanical properties of the InGaN/GaN/sapphire layers.The analysis of SE data was done using a parametric dielectric function model, established by in situ and ex situ measurements. A dielectric function database, optical band gap, the microstructure and the alloy composition of the layers were derived. The variation of the InGaN band gap with the In content (x) in the 0 < x ≤ 0.14 range was found to follow the linear law E_g = 3.44-4.5x.The purity and the stability of the GaN and InGaN crystalline phase were investigated by RS.     

Routes towards Anderson-like localization of Bose-Einstein condensates in disordered optical lattices

We investigate, both experimentally and theoretically, possible routes towards Anderson-like localization of Bose-Einstein condensates in disordered potentials. The dependence of this quantum interference effect on the nonlinear interactions and the shape of the disorder potential is investigated. Experiments with an optical lattice and a superimposed disordered potential reveal the lack of Anderson localization. A theoretical analysis shows that this absence is due to the large length scale of the disorder potential as well as its screening by the nonlinear interactions. Further analysis shows that incommensurable superlattices should allow for the observation of the crossover from the nonlinear screening regime to the Anderson localized case within realistic experimental parameters.     

The swelling and dissolution of cellulose crystallites in subcritical and supercritical water

The swelling and dissolution phenomena of microcrystalline cellulose (MCC) were investigated in subcritical and supercritical water. Commercial MCC was treated in water at temperatures of 250–380 °C and a pressure of 250 bar for 0.25–0.75 s. As reaction products, undissolved but depolymerised cellulose residue, short-chain cellulose precipitate, water-soluble cello-oligosaccharides and monosaccharides, as well as their degradation products, were detected. The highest yield of the cellulose II precipitate was obtained after a reaction time of 0.25 s at 360 °C. Our hypothesis was that if the crystallites were swollen, the depolymerization pattern would be that of homogeneous reaction and the cellulose Iβ to cellulose II transformation would be observed. The changes in the structure of the undissolved cellulose residue were characterised by size exclusion chromatography, wide-angle X-ray scattering and ¹³C solid-state NMR techniques. In many cases, the cellulose residue samples contained cellulose II; however, due to experimental limitations, it remains unclear whether it was formed through the swelling of crystallites or the partial readsorption of the dissolved cellulose fraction. The molar mass distributions of untreated MCC and after low intensity treatments showed a bimodal shape. After high intensity treatments the high molar mass chains disappeared which indicated a complete swelling or dissolution of the crystallites.     

龙爪芦荟和库拉索芦荟中微量锗的测定与红外光谱区别

采用吸光光度法对龙爪芦荟和库拉索芦荟中的微量锗进行了测定,并探讨了两种芦荟的红外光谱的区别。结果表明,龙爪芦荟中含锗量在26.1～28.6μg·g-1,回收率为91.6%～97 5%。库拉索芦荟中含锗量在16.8～20.0μg·g-1,回收率为87.1%～94.5%。两种芦荟的FT IR光谱图在2100cm-1处有明显差异,由此可区别两种芦荟。     

Krametosan, a new trinorlignan from the roots of Krameria tomentosa

A new phenylcoumarone type trinorlignan, krametosan (1), along with the known norlignans, ratanhiaphenol I (2) and 2-(2'-hydroxy-4',6'-dimethoxyphenyl)-5-(E)-propenylbenzofuran (3), the lignan conocarpan (4) and dinorlignan decurrenal (5), were isolated from the CHCl3 extract of the roots of Krameria tomentosa. The structure of these compounds were elucidated by the spectroscopic methods.