Spectroscopic studies of the sulphur afterglow

The afterglow emission spectrum of sulphur and argon mixture is found to consist of (a) the main band system of S₂(B³Σ^-_u?X³Σ^-_g) in the region 3200–6600 Å and (b) the atomic spectrum of argon in the 7500–9000 Å region. Although B?X bands of S₂ obtained by ordinary excitation extends from 2829 to 7100 Å, the lower wavelength limit of these bands from the afterglow is only 3200Å. It is proposed that the S₂ molecules are formed in the B³Σ^-_u state through inverse predissociation when two S atoms approach each other along the potential curve of the predissociating electronic state 1_u.     

Spectroscopic studies of high-voltage flash discharges

Hydrodynamic effects are considered for high-power sparks in supersonic electrode flames in relation to the spectroscopic parameters. These effects explain the high intensities of the lines and continuum as well as the line broadening in zones remote from the discharge channel.     

Spectroscopic studies of atmospheric interest on NO and NO

In recent years, high-resolution photoelectron spectroscopy and ab initio calculations have considerably revised and enlarged the understanding of the electronic structure of the NO and NO⁺ molecules. The experimental potential energy curves for the different electronic states of atmospheric interest molecules like NO and NO⁺ are constructed by using the Rydberg-Klein-Rees method as modified by Vanderslice et al. The ground state dissociation energies are determined by curve fitting technique using the five parameter Hulburt-Hirschfelder (H-H) function. The estimated dissociation energies are 6.381 and 10.693 eV for NO and NO⁺, respectively. These values are in good agreement with the literature values. The r-centroids and Franck-Condon factors (FC Factors) for the band system of B²Π_r-X²Π of NO and a³Σ⁺-X¹Σ⁺, A¹Π-X¹Σ⁺ of NO⁺ molecules have been calculated employing an approximate analytical methods of Jarmain and Fraser, and Nicholls and Jarmain. The absence of the bands in these systems is explained.     

Spectroscopic studies on Yb+ ions in liquid helium

An emission spectrum of the - (D1) transition and excitation spectra of the - (J=1/2 (D1) and 3/2 (D2)) transitions of Yb⁺ ions in liquid helium have been observed by means of a laser-induced fluorescence method. It has been found that all these spectra are blue-shifted from the ones in the free space, and also that the D2 excitation spectrum has double peaks. To understand these spectra, theoretical calculations have also been carried out based on a vibrating bubble model, in which the bubble surface is assumed to vibrate in the spherical (breathing), dipolar and quadrupolar modes. As a result, it has been found that the blue shifts are well understood with this bubble model, and also that the dynamic Jahn-Teller effect due to the quadrupole vibration of the bubble plays an important role for the double-peaked profile of the D2 excitation spectrum. Received 27 December 1999 and Received in final form 31 July 2000     

Spectroscopic studies of electron surface states on liquid helium

Field-ion microscopy has been previously used [1–4] to determine the surface energy anisotropy of tungsten and iridium. Drechsler and Nicholas [5] have used field emission patterns of equilibrium shapes of emitters to determine the surface energy anisotropies for a number of fcc and bcc metals including α-iron. The purpose of the present paper is to report some observations by field-ion microscopy on the vacuum faceting of α-iron and the surface energy anisotropy at about half the absolute melting point. Qualitative results on the effect of hydrogen on the surface energy anisotropy are also presented.     

痂囊腔菌素A与肌红蛋白相互作用的光谱研究

研究了痂囊腔菌素A(EA)与肌红蛋白(Mb)的相互作用.通过紫外-可见吸收光谱研究发现痂囊腔菌素A与肌红蛋白在避光与光照两种条件作用模式存在明显差异;痂囊腔菌素A对肌红蛋白的内源荧光有猝灭作用,形成了新的配合物,属于静态猝灭;热力学计算结果表明痂囊腔菌素A与肌红蛋白之间以疏水作用力结合.同步荧光光谱研究了痂囊腔菌素A对...     

Spectroscopic studies of tantalum doped borate glasses

Glasses with formula 30Li₂O 60B₂O₃xTa₂O₅ (10−x) Bi₂O₃ for x=0, 2, 4, 6 and 8 were prepared via normal melt quenching technique and characterized by refractive index and MDSC. Refractive index (μ) and glass transition temperature (T_g) are found to increase with increase in dopant concentration. Impedance spectra of the samples were recorded in the frequency range 100 Hz–5 MHz in the temperature range 175–275 °C. The plots are typical of those recorded for disordered systems. Conductivities and relaxation times are found to follow Arrhenius type of relation and activation energies are calculated. Optical absorption spectra were recorded in the wavelength range 200–900 nm range from which cutoff wavelength (λ_c) and optical band gap energy (E_g) are evaluated. λ_c is found to decrease while E_g to increase with increase in composition. FTIR spectra of the samples were recorded in the frequency range 400–1500 cm⁻¹ which exhibit characteristic bands corresponding to BO₃, BO₄ stretching vibrations and BO bending vibration. Tightening of the structure is indicated by increase in the vibration of BO₃ at the cost of BO₄ for 8 mol% of Ta₂O₅. This is in support of the highest value of T_g for this sample among the series. Raman spectra of the samples were recorded in the frequency range 200–1200 cm⁻¹. With successive addition of Ta₂O₅, increase in the vibration of Ta–O groups TaO₆ groups to be responsible for observed increase in μ and T_g. An attempt is made to prepare tantalum doped borate glasses and study them by spectroscopic techniques.     

Spectroscopic studies of electric discharges in electrospraying

The paper presents spectroscopic studies of electrical discharges, which take place in the electrospraying, and discusses the effect of electrical discharge on the spraying process. The experiments show that spectral lines, characteristic for the elements and compounds dissolved in the liquid to be sprayed can be identified in the emission spectra.     

Spectroscopic studies on vanadyl ion in rubidium magnesium sulphate hexahydrate

The optical absorption spectrum of VO²⁺ ion in a single crystal of Rb₂Mg(SO₄)₂6H₂O has been investigated both at laboratory and liquid nitrogen temperatures. The electron paramagnetic resonance (EPR) spectrum of the polycrystalline sample has also been investigated at the laboratory temperature. Both optical absorption and EPR spectra are characteristic of the VO²⁺ ion in tetragonal symmetry. Molecular orbital coefficients have been evaluated by correlating the optical absorption and EPR data.     

Spectroscopic studies of a flash X-ray discharge

By adjusting the crystal for reflection of a wavelength corresponding to a voltage higher than the initial one applied on the storage capacitor, it has been found from oscillographical recording of the detector output signal as well as thedI? waveform from the discharge, that mostly X-radiation of high intensity and short duration was produced during intervals characterized by decreasing discharge current. The results obtained is in accordance withHändel's theory that a pincheffect acts in the flash X-ray discharge, and as a result of this, a voltage increase across the flash tube electrodes.     

Spectroscopic and theoretical studies on a three-iron cluster with linear arrangement

The linear trinuclear iron complex Fe₃(SPh)₆(CO)₆ with bridging benzenethiolate ligands is the subject of temperature- and field-dependent Mössbauer studies. The results reveal the two terminal iron atoms to be diamagnetic (Fe(II) and the central iron atom to be high-spin Fe(II). The magnetic Mössbauer pattern of the latter is dominated by a positive (!) internal field. Complementary to the experimental studies, also theoretical studies are performed. Local density molecular orbital and ligand-field calculations yield an orbitally degenerate ground state that accounts for the unusual electronic and spectroscopic properties.     

Spectroscopic studies on the binding of barbital to bovine serum albumin

In this paper, the interaction between barbital and bovine serum albumin (BSA) was investigated by the method of fluorescence spectroscopy under simulative physiological conditions. Fluorescence data revealed that the fluorescence quenching of BSA by barbital was the result of the formation of BSA-barbital complex, and the effective quenching constants (K_a) were 1.468×10⁴, 1.445×10⁴ and 1.403×10⁴ M⁻¹ at 297, 303 and 310 K, respectively. The thermodynamic parameters enthalpy change (ΔH) and entropy change (ΔS) for the reaction were calculated to be −2.679 kJ mol⁻¹ and 70.76 J mol⁻¹ K⁻¹, respectively, according to the van’t Hoff equation. The results indicated that hydrophobic and electrostatic interactions were the dominant intermolecular force in stabilizing the complex. The results of synchronous fluorescence spectra showed that binding of barbital with BSA can induce conformational changes in BSA. In addition, the effects of Cu²⁺ and Zn²⁺ on the constants of BSA-barbital complex were also discussed.     

Spectroscopic studies of uranyl-acetonitrate complex formation in solutions

In the present work uranyl-acetonitrile complex formation is studied on the basis of analysis of vibrational (IR absorption and Raman) spectra of UO₂(NO₃)₂·6H₂O and UO₂(ClO₄)₂·7H₂O. From the present results and coordination critera for nitrate groups and acetonitrile, it is concluded that in the UO₂ (NO₃)₂·6H₂O-acetonitrile system, acetonitrile molecules are in the second coordination sphere of the uranyl ion. In a benzene solution of uranylperchlorate with added acetonitrile, acetonitryl is substituted for a water molecule in the first coordination sphere of the uranyl ion. In the coordination the vibration frequency of C≡H of acetonitrile (2240 cm⁻¹) is shifted by 21 cm⁻¹ to the shortwave region. Possible reasons for the relatively small change in this frequency are discussed. Belarusian State University, 4, F. Skorina Ave., Minsk, 220050, Belarus. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 3, pp. 179–183, March–April, 1997.     

Spectroscopic studies of ArF laser photoablation of PMMA

A Spectroscopic study has been made of the emission spectra arising from ArF laser initiated photoablation of PMMA samples. This process leads to direct etching of the polymer. The thermal temperature of the CH fragment species in the plume immediately above the ablated site was found to be 3200 ±200 K. The translational velocity of this species was found to be 4.2×10⁵ cm/s corresponding to a translational temperature of 11,000 K. These results are consistent with a rapid direct bond scission model for ablation.