Observation of dielectronic satellites in the K-spectrum of argon ions in plasma produced by femtosecond laser pulses

The satellite structure of 1s2p ^1,3 P ₁-1s ²¹ S ₀ lines of the He-like argon ion in plasma produced by a 45-fs laser pulse in a gas-jet cluster target is measured with a high spectral resolution. Radiation transitions 2p → 1s from autoionizing states (AISs) are detected for ions ranging from Li-like to F-like. The spectrum observed is theoretically simulated with the use of the spectroscopic data for the AISs of multicharged ions obtained within the multiconfiguration relativistic Hartree-Fock method. Good agreement with experimental data is obtained when the main population channels of these states are taken into account for typical values of cluster-target plasma parameters.     

Spin dynamics investigated by EPR in the paramagnetic regime of La2/3Ca1/3Mn1−x Me x O3 (Me = Al, In) manganites

We report an electron paramagnetic resonance (EPR) investigation of the spin dynamics in the paramagnetic regime of the colossal magnetoresistive manganites La_2/3Ca_1/3Mn_1?x Me _x O₃ (Me=Al, In;x≤0.05). The temperature dependences of the EPR linewidth and integral intensity have been analyzed in terms of the bottleneck spin relaxation and small-polaron hopping models. The exchange coupling integral between Mn³⁺ and Mn⁴⁺ ions and the polaron activation energy decrease with increasing doping level. A discussion is given concerning the factors which could explain the observed changes.     

A chemometric study of the simultaneous determination of calcium and magnesium in natural waters

A method for the simultaneous spectrophotometric determination of calcium and magnesium in mineral waters with an FIA system is tested. The method is based on the reaction between the analytes and arsenazo(III) at pH 8.5. The calculations of the amounts of both analytes in the samples are carried out with the H-point standard addition method (HPSAM) for ternary mixtures, and with a partial least squares (PLS) model after a proper variable selection. The results obtained for the determination of calcium were comparable using both methods. The employment of the HPSAM brings to our attention the influence of the calcium concentration in the sample to the development of the reaction between magnesium and arsenazo(III). HPSAM also permits to estimate the concentration of magnesium in the samples.     

Exploring the Effect of Ligand Structural Isomerism in Langmuir–Blodgett Films of Chiral Luminescent EuIII Self‐Assemblies

Here we have investigated the influence of the antenna group position on both the formation of chiral amphiphilic Eu^III‐based self‐assemblies in CH₃CN solution and, on the ability to form monolayers on the surface of quartz substrates using the Langmuir–Blodgett technique, by changing from the 1‐naphthyl ( 2(R) , 2(S) ) to the 2‐naphthyl ( 1(R) , 1(S) ) position. The evaluation of binding constants of the self‐ assemblies in CH₃CN solution was achieved using conventional techniques such as UV/Visible and luminescence spectroscopies along with more specific circular dichroism (CD) spectroscopy. The binding constants obtained for EuL , EuL₂ and EuL₃ species in the case of 2‐naphthyl derivatives were comparable to those obtained for 1‐naphthyl derivatives. The analysis of the changes in the CD spectra of 1(R) and 1(S) upon addition of Eu^III not only allowed us to evaluate the values of the binding constants but the resulting recalculated spectra may also be used as fingerprints for assignment of the chiral self‐assembly species formed in solution. The obtained monolayers were predominantly formed from EuL₃ (≈85 %) with the minor species present in ≈15 % EuL₂ .