Spectroscopic properties of the molecular ions BeX+ (X=Na,K, Rb): forming cold molecular ions from an ion–atom mixture by stimulated Raman adiabatic process

In this theoretical work, we calculate potential energy curves, spectroscopic parameters and transition dipole moments of molecular ions BeX⁺ (X=Na, K, Rb) composed of alkaline ion Be and alkali atom X with a quantum chemistry approach based on the pseudopotential model, Gaussian basis sets, effective core polarisation potentials and full configuration interaction. We study in detail collisions of the alkaline ion and alkali atom in quantum regime. Besides, we study the possibility of the formation of molecular ions from the ion–atom colliding systems by stimulated Raman adiabatic process and discuss the parameters regime under which the population transfer is feasible. Our results are important for ion–atom cold collisions and experimental realisation of cold molecular ion formation.     

A combining rule calculation of the ground-state van der Waals potentials of the magnesium rare-gas complexes

The potential energy curves and spectroscopic constants of the ground-state of the Mg–Rg (Rg = He, Ne, Ar, Kr, and Xe) van der Waals complexes are generated by the Tang–Toennies potential model and a set of derived combining rules. The parameters of the model are calculated from the potentials of the homonuclear magnesium and rare-gas dimers. The predicted spectroscopic constants are comparable to other available theoretical and experimental results, except in the case of Mg–He, we note that there are large differences between various determinations. Moreover, in order to reveal relative differences between species more obviously we calculated the reduced potential of these five systems. The curves are clumped closely together, but at intermediate range the Mg–He reduced potential is clearly very different from the others.     

β-Sonogel-Carbon electrodes: A new alternative for the electrochemical determination of catecholamines

In this work, a new alternative for the electrochemical determination of catecholamines based on β-cyclodextrin-Sonogel-Carbon electrodes is reported. The incorporation of β-CD and graphite in the preparation of the Sonogel-Carbon material leads to a modification of the electrode surface properties which causes a significant increase in the oxidation peak current of biomolecules such as dopamine, l-epinephrine, d,l-norepinephrine and catechol. This phenomenon might be attributed to the formation of an inclusion complex between β-CD and the catecholamines. The amount of β-CD necessary to form the Sonogel electrode was studied and optimization of electrochemical parameters, perm selectivity and mechanical stability of the sensor are discussed. Scanning electron microscopy and electrochemical impedance spectroscopy measurements were employed to characterize the electrical parameters and the structural properties of the new electrode surface, respectively. Cyclic voltammetry (CV) and Adsorptive differential pulse voltammetry (AdDPV) measurements were also used to explore the electrochemical behaviour of the electrode versus the quoted catecholamines. The β-CD-Sonogel-Carbon electrode offers fast and linear responses towards dopamine, norepinephrine, epinephrine and catechol, with good and low detection limits: 0.164, 0.294, 0.699 and 0.059 μmol L⁻¹, respectively.