Inelastic scattering and chemisorption of CO on a Pt(111) surface

A semiclassical model is used to calculate energy transfer in collisions between CO and a Pt(111) surface. The sticking probability is found to be as large as 0.7–0.8 for small collision energies (≈0.14 eV). At higher energies (≈5 eV) it decreases to ≈0.3. Strong interaction between the adsorbed molecule and the phonons is observed.     

Semiclassical calculation of energy transfer in polyatomic molecules. V. Differential cross sections for excitation of CO2 and N2O colliding with Li+ at E ≈ 4.72 eV

A semiclassical model has been used to calculate differential cross sections for vibrational excitation of CO₂ and N₂O at the center of mass collision energy E≈ 4.72 eV. Also the average rotational excitation as a function of the scattering angle is reported. Comparison is made with experimental data and previous more approximate theoretical calculations.     

Author index to volume 48

The vibrational energy transfer in a polyatomic molecule is described by introducing an irreducible set of operators. Each operator represents a specific interaction induced by the intermolecular potential. We present a graphic method which significantly facilitates the solution if the number of quantum modes (M) is large.     

Frequency Domain Methods and Decoupling of Linear Infinite Dimensional Differential Algebraic Systems

We discuss the analysis of linear constant coefficient differential algebraic equations on infinite dimensional Hilbert spaces. We give solution concepts and discuss solvability criteria which are mainly based on Laplace transform. Furthermore, we investigate the decoupling of these systems motivated by the Kronecker normal form for the finite dimensional case. Applications are given by the analysis of mixed systems of ordinary differential, partial differential and differential algebraic equations.     

Development of an improved method for trace analysis of chloramphenicol using molecularly imprinted polymers

A confirmatory method is described for the determination of the illegal antibiotic chloramphenicol using a specifically developed molecularly imprinted polymer (MIP) as the sample clean-up technique. The newly developed MIP was produced using an analogue to chloramphenicol as the template molecule. Using an analogue of the analyte as the template avoids a major traditional drawback associated with MIPs of residual template leeching or bleeding. The MIP described was used as a solid-phase extraction phase for the extraction of chloramphenicol from various sample matrices including honey, urine, milk and plasma. A full analytical method with quantification by LC-MS/MS is described. The method was fully validated according to the European Union (EU) criteria for the analysis of veterinary drug residues.     

Bis(4‐aminopyridinium) hexachloridostannate(IV) and bis(p‐toluidinium) hexachloridostannate(IV)

The crystal structures of the two organic–inorganic hybrids bis(4‐aminopyridinium) hexachloridostannate(IV), (C₅H₇N₂)₂[SnCl₆], and bis(p‐toluidinium) hexachloridostannate(IV), (C₇H₁₀N)₂[SnCl₆], differ in the way their cations pack in the layered structures. The Sn atom in the 4‐aminopyridinium compound lies on an inversion centre.     

Comparison of quantum mechanical and semiclassical cross sections for rotational excitation of hydrogen

Partial and integral cross sections for rotational transitions in He  H₂ have been calculated by a semiclassical coupled states method. The agreement with corresponding quantum mechanical values is excellent.     

Determination of arsenic in gold samples using matrix exchange differential pulse stripping voltammetry

A method comprising matrix exchange differential pulse stripping voltammetry (DPSV) at a gold film electrode has been proposed for the determination of small quantities of arsenic in pure gold. A wall-jet cell (WJC) and an on-line deoxygenation system were used to facilitate matrix exchange. The gold(I) cyanide complex was formed to avoid gold deposition on the electrode together with the arsenic. The pH of the sample solutions were adjusted to 3, as alkaline solutions gold(I) cyanide produced interference and the uncomplexed cyanide led to passivation of the gold film electrode. Matrix exchange electrolytes consisting of 4 mol l⁻¹ hydrochloric acid or a combination of 2 mol l⁻¹ sulphuric acid and 0.2 mol l⁻¹ hydrochloric acid could be utilised. Arsenic concentrations as low as 0.1 mg l⁻¹, could readily be detected in a gold matrix with a 60 s deposition time. While, cobalt and silver did not interfere with the arsenic determination, copper interfered even when present at similar concentrations to that of arsenic.