[en] This document proposes the table of contents and a brief presentation of a course book for students in atomic and molecular physics. After some generalities on energy quantification and on photon momentum / Compton Effect, the different chapters address topics like hydrogen and helium atoms, alkalis, alkaline-earth, atoms with several valence electrons, the atom-radiation interaction, molecule and ion spectroscopy in solids, and the most significant laser systems using an active media based on atoms, ions or molecules in a diluted environment. Each chapter contains exercises and problems

[en] The low phonon materials KPb₂Cl_5, CsCdBr₃ and Tl₃PbBr₅ were successfully grown by using the Bridgman-Stockbarger method. These crystals were stable, homogeneous, no moisture sensitive and could be doped with Pr³⁺ ions. Spectroscopic properties of the ³H₅→³H₄ Pr³⁺ transition have been investigated for the three low phonon materials. Absorption and emission cross sections of this transition around 3.8-5.5 μm are broad and present high peak values. Furthermore, gain cross sections derived from these measurements could be positive for small population inversion ratio. Finally, the performance of a continuous wave Pr-doped low phonon single-crystal laser operating on this transition is studied using numerical modelling. By this way it was possible to demonstrate that compact solid-state laser systems could be achieved via quantum-cascade laser (QCL) pumping.

[en] A detailed spectroscopic study of various Yb³⁺:CaF₂ crystals with dopant concentrations ranging from 0.03 to 2 at% Yb³⁺ has been performed. By using site-selective laser excitation, the low-temperature (7 K) excitation and emission spectra recorded in the case of the lower doped samples (0.03% and 0.05%) are found to be dominated by three types of sites with excited state fluorescence lifetimes of about 2, 8 and 10 ms. Confronted with crystal field calculations, these sites have been identified as Yb³⁺ ions in trigonal (C_3v), tetragonal (C_4v) and cubic environments, respectively. At higher dopant concentrations (>0.1 at%), evidence is found of a third kind of site, whose contribution increases up to be dominant as dopant concentration is increased above about 1 at%Yb³⁺ and which gives rise to the lasing center which has been recently discovered and operated