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Solid-state high-harmonic generation (HHG) by an intense infra-red (IR) laser field offers a new route to generate coherent attosecond light pulses in the extreme ultraviolet regime. The propagation of the IR driving field in the dense solid medium is accompanied by non-linear processes which shape the generating waveform. In this work, we introduce a monolithic scheme in which we both exploit the non-linear propagation to manipulate a two color driving field, as well as generate high harmonics within a single crystal. We show that the resulting non-commensurate, bi-chromatic, generating field provides precise control over the periodicity of the HHG process. This control enables us to manipulate the spectral positions of the discrete harmonic peaks. Our method advances solid-state HHG spectroscopy, and offers a simple route towards tunable, robust XUV sources.

The possibility to deposit CN x thin films by laser-induced CVD technique was investigated. For this purpose, different carbon/nitrogen containing mixtures and substrates were used. CO 2 and the KrF laser irradiations were employed. The deposition was alternatively performed on laser pre-deposited catalytic titanium thin films and on bare substrates (quartz and alumina). An XPS analysis of CN x film composition reveals that in the presence of Ti layers nitrogen incorporation is enhanced and chemical structures with higher transfer states are favored.

The results of a study on laser-assisted CVD of iron thin films from Fe(CO)5 vapour using a CO2 laser are presented. The iron-based layers deposited onto quartz substrates were characterised by different analytical techniques, and the influence of the precursor pressure and laser incident energy on the physical and chemical properties of films was pointed out. It was deduced that the purity of the as-deposited films depends on the different phases of carbon incorporation, which in turn is strongly influenced by the dynamics of the prevaling gas-phase processes.

High order harmonic generation from clusters is a controversial topic: conflicting theories exist, with different explanations for similar experimental observations. From an experimental point of view, separating the contributions from monomers and clusters is challenging. By performing a spectrally and spatially resolved study in a controlled mixture of clusters and monomers, we are able to isolate a region of the spectrum where the emission purely originates from clusters. Surpringly, the emission from clusters is depolarized, which is the signature of statistical inhomogeneous emission from a low-density source. The harmonic response to laser ellipticity shows that this generation is produced by a new recollisional mechanism, which opens the way to future theoretical studies., Comment: accepted at Physical Review Letters

We introduce High Harmonic Generation (HHG) as a new molecular chirality probe. Chiral sensitivity arises from non-planarity of electron trajectories in the continuum due to the influence of magnetic field of the laser.

We study the Cooper minimum in HHG from argon atoms using long wavelength laser pulses. We find that the minimum in high harmonic spectra is systematically shifted with respect to total photoionization cross section measurements. We use a semi-classical theoretical approach based on Classical Trajectory Monte Carlo and Quantum Electron Scattering methods (CTMC-QUEST) to model the experiment. Our study reveals that the shift between photoionization and high harmonic emission is due to several effects: the directivity of the recombining electrons and emitted polarization, and the shape of the recolliding electron wavepacket.

International audience; We present the possibility of carbon nitride fine powder synthesis by sensitized laser pyrolysis of acethylene/nitrous oxide/ammonia mixtures. The powders were analyzed using X-ray diffraction, X-ray photoelectron spectroscopy (XPS) and IR transmission measurements. It was found that nitrogen was incorporated in powders and that in the carbon-nitrogen phases formed, the presence of the triple bonded C≡N was not detected. The majority of X-ray diffraction data suggests the presence of a mixture of the predicted α- and β-C3N4 structure, with an α-C3N4-like form being prevalent. The powders were found to be slightly contaminated by SF6 sensitizer products. Our results suggest that by improving the experimental parameters this contamination might be reduced and that the laser pyrolysis method offers possibilities for production of CxNy materials, with controlled composition.

Laser-induced Fe(CO)5 decomposition at different vapor pressures was performed, and a comparative study of the films obtained thermally (at 10.6 ?m) and photolytically (at 248 nm) is presented. A perpendicular geometry of irradiation and quartz substrates were used. The influence of the incident laser energy on the growth rate and on the chemical content of the films was demonstrated. The film properties are discussed in connection with the irradiation conditions and specific mechanisms involved.

The carbon nitride (CN x ) films have been prepared by infrared (IR; at 10.6 μm) and ultraviolet (at 248 nm) laser induced chemical vapour deposition (CVD) using different ethylene/nitrous oxide/ammonia mixtures. The partial concentration of ammonia in mixtures was varied in order to obtain a higher nitrogen incorporation in the deposited films. The changes induced in the gas-phase composition by the laser radiation in different experimental conditions were determined by IR transmission measurements. The film composition was studied by X-ray photoelectron spectroscopy. The modification of the film chemical composition, specifically the dependence of the N C ratio, on the irradiation wavelength and on the reactants composition is described for the first time.

Laser-assisted processes for metal-based thin films deposition are currently using vapour-phase precursors. Eitherphotolytic or thermal, the mechanisms developed during laser-induced interaction between adsorbed precursor and substrate are imposing different trends to the composition and morphology of the growing metallic layer. Various aspects of the dynamics of film growth are discussed, in connection with the deposition oftitanium from titanium tetrachioride.Keywords: laser induced photochemistry, laser CVD, laser pyrolysis, laser photolysis. I . INTRODUCTION In the frame of the applications of lasers as tools for fine processing of surfaces, local deposition of films from vapour-phase is one of the most important and successfully developing field of tiga' Depending on the radiation action on the gas or absorbate precursor, laser methods are often roughly devided in photolytic or thermal-activatedprocesses. Metal containing precursors, either organometallics (carbonyls, alkyls) or inorganic salts (titanium chloride)