Laser-radiofrequency double-resonance spectroscopy of 13CH3I

Pure quadrupole resonances of the I¹²⁷ nucleus of ¹³CH₃I have been observed using laser-radiofrequency double resonance. Quadrupole coupling constants are reported for the ground, ν₃, 2ν₃, ν₆, 2ν₆, ν₃ + ν₆, and 2ν₃ + 2ν₆ states. Smaller hyperfine constants are also reported for the ground and ν₆ states.     

An application of the runge-kutta space

The Runge-Kutta space, a mathematical framework for discussing accuracy questions for initial value problems, is introduced and applied to the analysis of order conditions for a slight modification to the Runge-Kutta method. The modified method is proposed as a possible approach to breaking through various order barriers.Dedicated to Germund Dahlquist on the occasion of his 60th birthday     

10-μm sub-doppler laser-Stark spectroscopy of methyl chloride: Analysis of the ν6 bands of the CH335Cl and CH337Cl

About 900 Stark transitions from 70 vibration-rotation transitions in CH₃³⁵Cl and about 400 transitions from 38 transitions in CH₃³⁵Cl in the ν₆ band have been assigned. These data were analyzed simultaneously with previously published microwave data on the ν₆ = 1 state. The fit has a standard deviation of about 2 MHz for the data for both isotopes. The isoptopic shift ν₆35 ? ν₆37 = 0.3766(6) cm^?1. Rotational dependence of the dipole moment was also just apparent at about μ_J = μ_K = 1 × 10^?5 D, and a complete set of molecular constants is given.     

Linear and non-linear stability for general linear methods

We explore the interrelation between a number of linear and non-linear stability properties. The weakest of these,A-stability, is shown by counterexample not to imply any of the various versions ofAN-stability introduced in the paper and two of these properties, weak and strongAN-stability, are also shown not to be equivalent. Finally, another linear stability property defined here, EuclideanAN-stability, is shown to be equivalent to algebraic stability.     

Synthesis and structural studies on di-oxovanadium(V) complexes of N(4)-substituted pyrazole based thiosemicarbazones

Three mononuclear cis-dioxovanadium(V) complexes of tridentate thiosemicarbazones derived from 5-methyl-3-formylpyrazole (MPA) and N(4)-methyl/ethyl/dimethyl thiosemicarbazide have been synthesized and characterized. Single crystal X-ray analyses were performed with [VO₂L¹] (1), [VO₂L²] (2) and [VO₂L³] (3), where L¹, L² and L³ denote the [1 + 1] thiosemicarbazone mono-anions derived from MPA and N(4)-substituted methyl/ethyl/dimethyl thiosemicarbazide respectively. In all the complexes the vanadium atom is in a distorted square pyramidal geometry with a N₂SO₂ chromophore. The interesting finding in the work is that in complexes 1 and 2, the thioimine nitrogen unusually participates in coordination whereas in 3 it is the azomethine nitrogen (quite usual) which is involved in the coordination process.     

Characterizing void nucleation in a damage-based constitutive model using notched tensile sheet specimens

An experimental and numerical test programme was conducted to investigate damage-induced ductile fracture in notched tensile sheet specimens of an aluminum–magnesium alloy. An upper bound, damage-based constitutive model was employed to estimate the formability of the material over a range of stress states found in sheet metal forming. Stress- and strain-based nucleation models are evaluated to characterize damage initiation and fracture of the material. The ligament strain-to-failure, elongation-to-failure and load–displacement curves can be captured using either nucleation rule. The advantages of each nucleation model are discussed in relation to quantitative measurements of damage available in the literature. Stress-based nucleation provides a promising approach for characterizing the nucleation behaviour over a range of stress states compared to strain-based nucleation.     

A Sandmeyer type reaction for bromination of 2-mercapto-1-methyl-imidazoline (N2C4H6S) into 2-bromo-1-methyl-imidazole (N2C4H5Br) in presence of copper(I) bromide

2-Mercapto-1-methyl-imidazoline (N(2)C(4)H(6)S) is converted at room temperature into 2-bromo-1-methyl-imidazole (N(2)C(4)H(5)Br) in presence of copper(I) bromide in acetonitrile-chloroform mixture via extrusion of sulfur as sulfate and oxidation of Cu(I) into Cu(II). 2-Bromo-1-methyl-imidazole was isolated as its self assembled tetranuclear Cu(II) cluster, [Cu(4)(η(1)-N-(N(2)C(4)H(5)Br)(4)(μ(4)-O)(μ-Br)(6)] 1 {η(1)-N-(N(2)C(4)H(5)Br) = 2-bromo-1-methyl-imidazole}.