Electron temperature (T e) measurements by Thomson scattering system

Thomson scattering technique based on high power laser has already proved its superoirity in measuring the electron temperature (T _e and density (n _e) in fusion plasma devices like tokamaks. The method is a direct and unambiguous one, widely used for the localised and simultaneous measurements of the above parameters. In Thomson scattering experiment, the light scattered by the plasma electrons is used for the measurements. The plasma electron temperature is measured from the Doppler shifted scattered spectrum and density from the total scattered intensity. A single point Thomson scattering system involving a Q-switched ruby laser and PMTs as the detector is deployed in ADITYA tokamak to give the plasma electron parameters. The system is capable of providing the parameters T _e from 30 eV to 1 keV and n _e from 5 × 10¹²cm⁻³−5 × 10¹³cm⁻³. The system is also able to give the parameter profile from the plasma center (Z=0 cm) to a vertical position of Z=+22 cm to Z=−14 cm, with a spatial resolution of 1 cm on shot to shot basis. This paper discusses the initial measurements of the plasma temperature from ADITYA.     

New relationships connecting the dipole polarizability, radius, and second ionization potential for atoms

The atomic dipole polarizability α of the 101 elements from He to No is related to the second ionization potential I? and the Waber-Cromer radius r(WC). Our recommended model is the function α = P?·I??? + P?·r(WC)(3) I?(y). With the parameters P? = 2.26, P? = 3.912, and y = 0.439, it reproduces the polarizabilities of all 101 elements with a mean absolute deviation of 7.5 au.     

When does the non-variational nature of second-order Møller-Plesset energies manifest itself? All-electron correlation energies for open-shell atoms from K to Br

All-electron correlation energies E(c) are not very well known for open-shell atoms with more than 18 electrons. The complete basis-set (CBS) limits of second-order M?ller-Plesset (MP2) perturbation theory energies are obtained for open-shell atoms by computations in large basis sets combined with a knowledge of the MP2/CBS limit for the next larger closed-shell atom with the same valence shell structure. Then higher-order correlation corrections are found by coupled-cluster calculations using basis sets that are not quite as large. The method is validated for the open-shell atoms from Al to Cl for which E(c) is reasonably well established. Then, the method is used to obtain non-relativistic E(c) values, probably accurate to 3%, for the open-shell atoms of the fourth period: K, Sc-Cu, and Ga-Br. These energies are compared with the predictions of 19 density functionals and may be useful for the parameterization of new ones. The results show that MP2 overestimates |E(c)| for atoms heavier than Fe.     

Cyclopropanation of poly(isoprene) using NHC-Cu(I) catalysts: Introducing carboxylates

The incorporation of functional groups into unsaturated polyolefine-polymers often represent a challenging task. Based on the known cyclopropanation of double bonds with diazoesters in the presence of metal-catalysts of low molecular weight compounds, we in this article develop an approach to decorate the polymer backbone of poly(diene)s with ester as well as carboxylic groups via cyclopropanation. Therefore, predominantly cis-1,4-poly(isoprene)s are converted with ethyl or tert-butyl diazoacetate using copper(I) N-heterocyclic carbene (NHC) catalysts, while focusing on the technically relevant cyclohexane as solvent. The application of commercially available NHC-Cu(I) catalysts results in modification degrees of 4–5%, while an increased solvent polarity, like dichloromethane, results in up to 17% modification. The resulting esters were further converted to the corresponding free carboxylic groups by deprotection using trifluoroacetic acid. Thus, an introduction of functional groups along the polymer backbone with a wide variety of application, like ionic interaction or hydrogen bonding motifs, was successfully demonstrated. Its potential for upscaling makes this approach feasible for an application in large-scale production processes, such as for manufacturing of modified synthetic rubbers.     

I2 as an efficient catalyst in ionic Diels-Alder reactions of α,β-unsaturated acetals

A variety of protected and unprotected α,β-unsaturated aldehydes react with 1,3-dienes in the presence of I₂ to give the corresponding cycloadducts.     

Gross alpha determination in salt rich water samples using an extraction chromatographic resin and LSC

The application of an extraction chromatographic resin to the determination of the gross alpha activity of drinking water samples with volumes greater than 100 ml and of salt rich aqueous samples, like mineral, waste or sea waters was tested. Alpha-emitters are extracted from the water sample onto the resin, the gross alpha activity is then determined by direct measurement of the dried resin using α/β discrimination LSC. The resin shows strong affinity for actinides, as well as for radium, out of pH 2 solutions. The extraction is robust against Ca, sulphate and other potential interferents. The method was tested by analyzing reference materials, intercomparison samples and spiked real samples. Results of good precision and accuracy were obtained in counting times notably shorter than routinely used for gas proportional counting.     

More on basis set quality tests

The quality measure δ of Sordo and Pueyo is computed for 94 orbital basis sets for the atomic helium Hartree-Fock problem and compared with various information theoretic quality measures reported previously by us for this data base. δ is in error often enough that it is unlikely to be a useful general purpose measure.     

The quality of s-orbitals determined by least-squares fitting and constrained variational methods

Calculations of a wide range of position and momentum space properties of 23 orbital basis sets for atomic helium are performed to supplement our previous work. The combined results on 94 orbital basis sets are used to demonstrate that, as in the case of d-orbitals, the least squares error is not as discriminating as other information theoretic measures of overall quality for s-orbitals. Detailed comparisons suggest that constrained variation can improve the overall quality of the resulting orbital provided that the constraints are selected carefully to complement the bias inherent in the energy expectation value and the functional form of the basis functions.     

Polarizabilities of the alkali anions: Li- to Fr-

Static dipole polarizabilities are calculated for the ground states of the alkali anions from Li- to Fr-. The polarizabilities include scalar relativistic effects at the second-order Douglas-Kroll level and were computed using the finite-field, coupled-cluster CCSD(T) method with large, carefully optimized basis sets. The relativistic polarizabilities increase with Z, reach a maximum at Cs-, and then decrease again unlike their nonrelativistic counterparts which increase monotonically with Z.