有机硅活性中间体的研究 II. 一些含环丙基的有机硅化合物的合成及其结构

用锂有机物的方法合成了四种含有环丙基有机硅化合物,对上述每种化合物中可能存在着的立体异构进行了分离和和构型测定。     

Synthesis and spectral characterization of zinc(II) complexes of N(4)-substituted thiosemicarbazone derived from salicylaldehyde: Structural study of a novel –OH free Zn(II) complex

Five novel zinc(II) complexes of salicylaldehyde 3-hexamethyleneiminyl thiosemicarbazone were synthesized and physico-chemically characterized. The complexes were given the formulae [Zn(HL)₂] (1), [Zn(L)py] (2), [Zn(L)bipy] · 3.5H₂O (3), [Zn(L)phen] · H₂O (4) and [Zn(L)γ-pic] (5). The thiosemicarbazone binds the metal as a dianionic ONS donor ligand in all the complexes, except in 1. Compound 1 is a homoleptic complex with zinc occupying the center of a distorted tetrahedral environment and being coordinated by two azomethine nitrogen and two thiolate sulfur atoms.     

Thermal lens technique to evaluate the fluorescence quantum yield of a schiff base

The fluorescence spectrum of the schiff base obtained from salicylaldehyde and 2-aminophenol is studied using an argon-ion laser as the excitation source and its fluorescence quantum yield (Q_f) is determined using a thermal lens method. This is a nondestructive technique that gives the absolute value of Q_f without the need for a fluorescence standard. The quantum-yield values are calculated for various concentrations of the solution in chloroform and also for various excitation wavelengths. The value of Q_f is relatively high, and is concentration dependent. The maximum value of Q_f obtained is nearly 0.78. The high value of the fluorescence quantum yield will render the schiff base useful as a fluorescent marker for biological applications. Photostability and gain studies will assess its suitability as a laser dye. PACS 42.55.Mv; 42.62.Cf; 42.62.Fi; 42.70.Hj     

Excited atomic state of Li

An optical transition of 3489 A has been shown to arise from Li using beam foil spectroscopic technique. The mean life of the state emitting this radiation has been measured to be 2.23 ä 0.08 n sec.     

A crystallographic study of 2-hydroxyacetophenone N(4)-cyclohexyl thiosemicarbazone

The crystal structure of 2-hydroxyacetophenone N(4)-cyclohexyl thiosemicarbazone is described. The compound crystallizes in the triclinic crystal system, space group , Z = 4, V = 1569.6(3) ?³ with unit cell parameters a = 6.9436(8) ?, b = 12.4762(15) ?, c = 18.588(2) ?, α = 100.187(2)°, β = 97.069(2)° and γ = 92.340(2)°. There are two independent molecules in the asymmetric unit. The crystal structure reveals that the compound exists in the thione form and S1 and N1 are at E configuration to each other with respect to N2-C8 bond. Similarly, S2 and N4 are trans to each other with respect to N5-C23 bond in the second molecule of the asymmetric unit. The packing of the molecules in the crystal lattice is stabilized by intermolecular hydrogen bonds.     

Development and Calibration of a Portable Air Sampler

This paper describes the development and calibration of a portable air sampler for detecting chemical vapors. The air sampler is equipped with a preconcentrator, a battery operated mini-pump, a three-way valve, capacitive sensors housed in a sensing chamber, and a data acquisition and control circuit board. The preconcentrator is used to adsorb trace level chemicals and to thermally desorb them into the sensing chamber. The air sampler was calibrated using known concentrations of ethylbenzene vapor generated by an Environics gas mixing system. The air sampler was also tested using low concentration toluene and ethanol vapors generated by diffusion based vapor generation device. The concentration factor of the preconcentrator was experimentally determined.     

Polarized Raman scattering in single crystals of Nd0.7Sr0.3MnO3

We report polarized Raman scattering in single crystals of Nd_0.7Sr_0.3MnO₃. The temperature dependence of the MnO₆ octahedral bending and stretching modes observed in the XX spectra points to the existence of local lattice distortions, possibly polarons. The XY spectra have been analyzed using a collision-dominated model, which allows the extraction of the carrier scattering rate.     

Hyperfine fields at implanted119Sn in Fe

Metastable FeSn systems produced by high dose implantation of¹¹⁹Sn into Fe foils are studied by conversion electron Mössbauer spectroscopy. The hyperfine field experienced by Sn implanted in Fe depends on the implantation dose. Clustering and precipitation of Sn take place at doses of 5x10¹⁶/cm² and beyond. Isochronal annealing of the implanted sample at 500 C causes the Sn atoms to move towards the surface, probably due to vacancy assisted migration, resulting in the precipitation of almost the entire implanted Sn on the Fe surface. This precipitate acts as a source for the in-diffusion of Sn into Fe at 600 C.     

Characterisation of nickel(II) complexes of a substituted 2-acetylpyridine thiosemicarbazone by electronic and n.m.r. spectral studies

Summary Ni^II complexes of 1H-hexahydroazepine-1-thiocarboxylic acid-2-[1-(2-pyridinyl)ethylidene] hydrazide (HL4A) of general formula [Ni(L4A)X] (X=Cl, Br, I or NCS) have been synthesized and characterised by physical and spectroscopic methods. The molar conductivities show that all of the complexes are non-electrolytes. The terdentate character of the ligand in all cases is inferred from i.r. spectra, while the electronic spectra suggest planar geometries.     

Structural and spectral investigations on some new Ni(II) complexes of di-2-pyridyl ketone N(4)-phenylthiosemicarbazone

Ni(II) complexes (1–5) of di-2-pyridyl ketone N(4)-phenylthiosemicarbazone (HL) have been synthesized and spectrochemically characterized. Elemental analyses revealed a NiL₂ · 2H₂O stoichiometry for compound 1. However, the single crystals isolated revealed a composition NiL₂ · 0.5(H₂O)0.5(DMF). The compound crystallizes into a monoclinic lattice with the space group P2₁/n. Complexes 2, 3 and 4 are observed to show a 1:1:1 ratio of metal:thiosemicarbazone:gegenion, with the general formula NiLX · yH₂O [X = NCS, y = 2 for 2; X = Cl, y = 3 for 3 and X = N₃, y = 4.5 for 4]. Compound 5 is a dimer with a metal:thiosemicarbazone:gegenion ratio of 2:2:1, with the formula [Ni₂L₂(SO₄)] · 4H₂O.