Rydberg atoms in magnetic fields — The landau limit of the atomic spectrum

We present some of the more striking experimental aspects of the quasi-Landau atomic spectrum in a magnetic field, observed near and above the zero field ionization threshold. The Landau limit is shown to be almost reached in our experiments on caesium, led at fixed electron energies scanning the magnetic field.     

Rydberg atoms in crossed electric and magnetic fields. Experimental evidence for the Pauli quantization

The experimental evidence for the Pauli quantization obeyed by the Rydberg spectrum of rubidium, in crossed electric and magnetic fields, is reported. When the external field perturbation associated with Zeeman and linear Stark effects are of the same order but small compared to the Coulomb binding energy, the energy levels of the system are given by $\text{E}{}_{\mathrm{n,k}}\text{= -R/n}{}^2\text{+ ɡK (ω}{}^2{}_{\mathrm{L}}\text{+ ω}{}^2{}_{\mathrm{E}}\text{)}{}^{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$, where K is an integer ω_L, ω_E the Larmor and linear Stark frequencies respectively.     

Early building up of the quasi Landau spectrum in the diamagnetic coulomb region

We report the results of experimental measurements on atomic diamagnetism in inter-l and inter-n mixing conditions. They have been obtained using high resolution techniques on highly hydrogenic M = ± 3 states of cesium, providing a pure experimental situation. Comparison with straightforward hydrogenic calculations and semi-classical predictions allow identification of the dominant lines of the spectrum which are shown to behave as precursors of the quasi Landau spectrum.     

Moisture effects in lithium-doped polyimide films

The interaction of lithium-doped polyimide films with water has been investigated. Contact angle and water absorption/desorption measurements have been performed to obtain an idea of the hygroscopic nature of these lithium-doped films. Contact angles were found to decrease as the amount of surface lithium increased. Film water content was also found to increase as the weight percent of total lithium content in the film increased. This phenomenon has been used to rationalize the electrical resistivity–temperature profile of certain lithium films which display an increase in electrical resistivity upon drying.     

Alkylation of manganese(II) tetraphenylporphyrin by a synthetic antimalarial trioxane

The synthesis and the antimalarial activity of a new kind of polycyclic 1,2,4-trioxanes are reported. The alkylation of the heme model MnIITPP by the biologically active (IC 50 = 320 nmol L-1) hemiperketal 2 is presented.     

Studies of thermal cyclizations of polyamic acids and tertiary amine salts

Thermal conversion rates of the polyamic acid derived from pyromellitic dianhydride and 4,4′-diaminodiphenyl ether are presented. Formation of the imide ring proceeds by fast and slow first-order processes. Tertiary amines give ring closures faster by a factor of 10 than the free acid. The enhancement is an activation entropy rather than an activation energy effect.