Determination of alkali metals by laser-induced atomic-ionization in flames

The technique of laser-induced atomic-ionization (AI) in flames has been used for direct determination of Na, K, Rb, and Cs in samples such as water, high-purity alkali metals and their salts and polymeric organosilicon compounds. Different procedures for sample introduction into the flame were studied: (a) the sample was placed onto the cathode of the detector (this gave limits of detection for Na and Cs of 4 x 10(-16) and 2 x 10(-15) g, respectively), (b) electrothermal vaporization and (c) aspiration of the sample into the flame. To reduce the interference of SiO(2) in the AI determination of K in polymeric organosilicon compounds (at the level of 10(-3)-10(-5)%), a procedure involved additional electrical heating of the FID cathode was developed. The efficiency of certain schemes for the laser stepwise and two-photon excitation of atoms was compared for determination of Na.     

Nitration of sulfate lignin under homogeneous conditions studied by electron spectroscopy

Russian Chemical Bulletin - The nitration of sulfate lignin by nitric acid in an aqueous-dioxane medium under homogeneous conditions was studied. The method proposed makes it possible to synthesize...     

Determination of the B1Π-X1Σ and C1Σ-X1Σ electronic transitions strengths of CaO

The strengths S_e of the B¹Π-X¹∑ and C¹∑-X¹∑ electronic transitions of the CaO molecule have been determined by absorption measurements in a shock tube. Powdered calcium oxide and a gaseous mixture of oxygen and argon in the ratio of 1:5 or 1:9 were introduced into the shock channel. The CaO gas-phase concentration was determined by using the equilibrium constant for CaO?Ca+O; atomic oxygen concentration was calculated and that of calcium was measured spectroscopically. The values of S_e (in atomic units) are for B¹Π-X¹∑, 2.32±0.49; for C¹∑-X¹∑, 2.88±0.67.     

Photoprocesses induced by short-wavelength excimer laser radiation in adsorbed halomethane molecules

Photolysis and desorption induced by ArF and KrCl laser irradiation of CH₂I₂, CH₃I, CCl₄, CHCl₃, CH₂Cl₂, CF₂Cl₂, and CHF₂Cl molecules adsorbed on fused silica were studied. One-photon fragmentation, as well as nonlinear dissociation and desorption processes, were observed. It was found that three-step fragmentation is a widespread phenomenon for molecules that experience resonant absorption of laser radiation. To explain the phenomenon, a mechanism based on stimulated emission was proposed. The nonlinear character of desorption is associated with redistribution of absorbed energy in adsorbed molecules and its transfer to the substrate.     

Synthesis of a magnetoactive compound by the interaction of iron(II) sulfate with potassium chromate

A study was made of the effect of synthesis conditions on the properties of a magnetoactive compound obtained by the interaction of iron(II) sulfate with potassium chromate. It was found that, in the formation of the magnetoactive compound, chromium is almost completely coprecipitates with the solid phase. To produce the magnetoactive compound with high relative magnetic susceptibility, it is necessary to precipitate it from the initial solution in no less than 10 min after its preparation at a K₂CrO₄: FeSO₄ molar ratio of 0.16–0.18.