Infrared emission spectroscopy of a new Σ-Σ system of TiCl

The spectra of TiCl have been reinvestigated in the 4200-8500 cm⁻¹ region using the 1-m Fourier transform spectrometer associated with the National Solar Observatory at Kitt Peak. The molecules were excited in a microwave discharge lamp operated with 3.0 Torr of He and a trace of TiCl₄ vapor, and the spectra were recorded at a resolution of 0.01 cm⁻¹. Three new bands with origins near 6938.9, 6900.2, and 6861.7 cm⁻¹ have been assigned as the 0-0, 1-1, and 2-2 bands of a new - transition. This assignment is supported by our recent ab initio calculations on TiCl and ZrCl [J. Chem. Phys. 114 (2001) 3977]. A rotational analysis of these bands has been carried out and spectroscopic constants have been extracted for the states.     

Effect of Phosphate on the Self-Assembly of Peptide EMK16-Ⅱ

The ionic-complementary peptide EMK16-Ⅱ is used to investigate the effects of hydrophobic and electrostatic interactions on the self-assembling process by atomic force microscopy and circular dichroism spectra. It is found that the increase of hydrophobicity of the peptides promotes the aggregation of fibrils in pure water. The effects of phosphate with different concentrations on electrostatic interactions are also investigated. It is found that the self-assembling process is enhanced at a low concentration of phosphate and more ordered fibrillar aggregates are formed. When the concentration of phosphate increases to a certain value （9mM）, only a few fibrils are found to be formed. No fibrils but amorphous aggregates exist when the concentration further increases. A physical interpretation is presented such that one divalent anion can interact with two positively charged residual groups in different peptide molecules like a ＂bridge＂ which destroys the ionic-complementary feature and largely inhibits the formation of ordered fibrils.     

Equation of State of Nuclear Matter in Chiral σ-ω Model

The equation of state of nuclear matter is studied in the 1-loop approximation of chiral linear σ-ω model. By introducing the density-dependent coupling constants, the problem of tachyon pole in the chiral σ-ω model is resolved. The 1-loop contributions of σ and π mesons to the nucleon's binding energy are included, while the empirical properties of nuclear matter such as saturation density, binding energy, and incompressibility are well reproduced.     

Study of Σ~*-Δ Interactions

We study the Σ~*-Δ interaction in the chiral SU(3) quark model and in the extended chiral SU(3) quark model.In these two models,the short-range interaction mechanism are totally different,one is from the one-gluon exchange and another is from the vector meson exchange.The possible reasons of forming strangeness-1 bound states are given.Comparisons between the cases with and without quark exchange effect are made.The results show the quark exchange effect does give attractions to (Σ~*Δ)_(ST)=0 5/2 and (Σ~*Δ)_(ST)=3 1/2 systems,which means the special symmetry is important.Also,we make some analysis on chiral field effect,our results show that the σ exchange dominantly provides the attractive interaction for these two states.     

Luminescence of Cu+-β“-alumina

A series of monovalent copper containing β-alumina single crystals have been prepared by standard ion exchange techniques. The crystals exhibit strong luminescence which we attribute to the 3d⁹4s → 3d¹⁰ interconfigurational transition. The peak wavelength of this transition can be varied by 135 nm by the presence of other cations in the β“-alumina conduction plane, allowing the luminescence to be varied throughout the visible spectrum. Single-pass gain measurements of several of these crystals show gains of the order of 0.1/cm, suggesting the potential use of these materials for solid-state tunable lasers.     

Equation of State in the σ-ω-ρ Model Supported by the Observational Data of 4U 1608-52 Neutron Star

The properties of the neutron star rotating at 619Hz （which is the spin frequency of 4U 1608-52 neutron star） are investigated by using an equation of state （EOS） of the nuclear matter in the relativistic σ-ω-ρ model. It is shown that the EOS in the relativistic σ-ω-ρ model is supported by the observational mass and radius of the 4U 1608-52 neutron star. Moreover, a
strict constraint on the polar redshift of 4U 1608-52 neutron star is obtained.     

Dynamics of Solvent Controlled ESIPT of π-Expanded Imidazole Derivatives - pH Effect

A set of π-expanded imidazole derivatives employing excited state intramolecular proton transfer (ESIPT) was designed and synthesized. The relationship between the structure and photophysical properties were thoroughly elucidated by comparing with the analogue blocked with ESIPT functionality. The compound possessing an acidic NH function as part of an intramolecular hydrogen bond system has much higher fluorescence quantum yield and Stokes shift and the π-expansion strongly influences the optical properties. The occurrence of ESIPT for imidazole tosylamide derivatives were less affected by the hydrogen-bonding ability of the solvents compared to the unprotected amine. The low pKa values for the monocation ? neutral equilibrium indicate the presence of intramolecular hydrogen bonding between the amino proton and tertiary nitrogen atom.     

Spectrophotometric Study of Basicity of Some Substituted α-(Benzamtoomethyl)phenylhydrazines

The protonation behavior at 25°C in water and in aqueous sulfuric acid solutions of some substituted α-(p-R-benzamidomethyl)phenyl hydrazines (R=H, CH₃, Cl, Br) was investigated by UV spectrophotometry. The absorption spectra in sulfuric acid solutions were analyzed by the method of multivariate analysis. The premonition constants of hydrazine (pK₁) and amide (pK₂) moieties were determined; pK₂ values were calculated from the reconstituted absorption spectra by Cox - Yates method. Dependence of pK₂ on Hammett's a constants was discussed.     

The first high-resolution analysis of the 10-μm absorption of thioformaldehyde

The 10 μm region of thioformaldehyde (H₂CS) has been recorded at high resolution (0.005 cm⁻¹) using a Fourier transform spectrometer. H₂CS was produced by low-pressure pyrolysis of a gas flow of C₃H₅SCH₃ in Ar at 560 °C or CH₃SCl at 1150 °C, which was introduced into a multipass White cell with an optical path length of 32 m. Forty scans were recorded for the range 750-1400 cm⁻¹ at a total pressure of 0.15 mbar. A thorough analysis of the three lowest wavenumber fundamental bands, ν₃, ν₄ and ν₆, which fall in this region, has been carried out using a Hamiltonian model, which takes explicitly into account the numerous resonances affecting the ro-vibrational energy levels; especially the massive A-type Coriolis resonance between the out-of-plane wagging mode, ν₄, and the in-plane rocking mode, ν₆. These two modes are only separated by 0.83 cm⁻¹, and they are thoroughly mixed. From the fittings, the following band centers were derived: ν_o (ν₄)=990.18213(40) cm⁻¹, ν_o (ν₆)=991.02021(50) cm⁻¹ and ν_o (ν₃)=1059.20476 (30) cm⁻¹ where the uncertainties are one standard deviation. In addition, a number of relative line intensities were measured permitting the determination of relative values of the first-order transition moments and therefore relative band intensities for all three bands. Finally, a comprehensive list of line wavenumbers and relative intensities has been generated.     

Puzzle of low temperature phase of α-(ET)2 salts

α-(ET)₂ salts split into two groups: one superconducting and another with mysterious low temperature phase (LTP). The LTP does not exhibit X-ray signiture of conventional CDW or magnetic one for SDW. But the magnetic phase diagram suggests strongly a kind of CDW. We have analysed the threshold electric field of unconventional CDW (UCDW) both for H=0 and H≠0. The threshold electric field for UCDW with H=0 and for 3D weak-pinning limit describes reasonably well the one determined in α-(ET)₂KHg(SCH)₄. The result for H≠0 is also presented. We propose that the LTP in α-(ET)₂ salts is most likely UCDW.     

The phase behaviour of 4- n -pentylphenyl-4′- n -heptyloxythiobenzoate

New results of investigations of phase polymorphism for two substances, hydrogenous (7OS5-d₀) and partially deuterated (7OS5-d₂₆) have been presented. On the basis of measurements of the integrated “elastic window” intensity (EL), quasielastic neutron scattering (QNS) spectra and results obtained with the Transmitted Light Intensity (TLI) method, the metastable character of the SmC phase, that at constant temperature always transforms to the crystalline phase Cr₂, has been confirmed. Variations of the EL show a very clear hysteresis effect in the nematic and SmC phases as well as in solid phases. It was confirmed by a phase polymorphism in both investigated substances. Convergence of the EL and TLI methods was shown. The new phase situation of both hydrogenous and partly deuterated liquid crystals is presented.     

Interaction of 1-(β-oxyethyl)-2-methyl-5-nitroimidazole with the surface of highly dispersed silica

Using the IR spectroscopy method, it has been established that formation of a monolayer 1-(β-oxyethyl)-3-methyl-5-nitroimidazole (metronidazole) on the surface of nonporous amorphous highly dispersed silica (S_sp = 230 m²/g) occurs during its absorption in an amount of 0.6 mmole/g. Such a content of adsorbate corresponds to the concentration of free silanol groups that are main active centers of the surface. Based on the analysis of the IR spectra of the specimens obtained and the dependence of the degree of perturbation of silanol groups on the content of adsorbed metronidazole, the structure of the surface adsorption complexes is suggested. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 72, No. 6, pp. 717–721, November–December, 2005.     

Fourier Transform Emission Spectroscopy of a New Φ-1Δ System of VO

High-resolution emission spectra of VO have been recorded in the region 3400-19 400 cm⁻¹ using a Fourier transform spectrometer. The molecules were observed from the reaction of VOCl₃ with active nitrogen. Two new bands, with origins near 5539.46 and 5551.69 cm⁻¹, are assigned as the 0-0 bands of the ²Φ_5/2-²Δ_3/2 and ²Φ_7/2-²Δ_5/2 spin-orbit components (respectively) of a ²Φ-1²Δ electronic transition of VO. A rotational analysis of both subbands has been carried out and spectroscopic constants have been extracted. The 1²Δ state is known from the previous analysis of the near infrared doublet transitions of VO and the new ²Φ excited state has rotational constants very similar to those of another ²Φ state observed previously [Merer et al., J. Mol. Spectrosc.125, 465 (1987)].     

Model of grain-boundary self-diffusion in α- and β-phases of titanium and zirconium

A model of the grain-boundary self-diffusion process in metals undergoing phase transitions in the solid state is proposed. The model is based on the ideas and approaches of the theory of nonequilibrium grain boundaries. It is shown that the range of application of basic relations of this theory can be extended, and they can be used to calculate the parameters of grain-boundary self-diffusion in high-temperature and low-temperature phases of metals with phase transition. Based on the constructed model, activation energies of grainboundary self-diffusion in titanium and zirconium are calculated, and their anomalously low values in the low-temperature phase are explained. The calculated activation energies of grain-boundary self-diffusion are in good agreement with experimental data.     

Investigation of output parameters of a 4.3-μm longitudinal-discharge CO2 laser

A simple hot-cell-free 4.3-m CO₂ laser with longitudinal d.c. discharge is described and the results of its parametrization are presented. It is shown that for effective operation of the 4.3-m (10° 1-10°0 band) CO₂ laser, use of active mixtures containing 4 to 5% of carbon dioxide with 20% nitrogen is needed. The laser is mechanically Q-switched producing peak powers in excess of 60 W with a pulse duration of 300 ns FWHM. The 4.3-m laser is easily tunable and operates on the P and R branches of the 10°1-10°0 band of CO₂. The peculiarities of spectral performances are discussed.