Methode d''excitation du spectre Raman d''une couche mince utilisant un reseau a grand nombre de traits

The Raman spectrum of a dielectric substance deposited in a few microns thick film on a diffraction grating (aluminium coating), is obtained with a trapped laser beam inside the film. In order to assure the most efficient coupling, a single mode of propagation is excited in “reverse coupling”; the selection of groove spacing is discussed.     

529—Chemical reactions and oscillating potential difference variations at an oil-water interface

Oscillatory potential and difference interfacial tension variation can be observed at an oil-water interface containing charge species when the conditions are such that hydrodynamic instabilities can occur. We propose a mechanism based on an experimental study accountable for the relaxation-type oscillations observed. It involves the coupling of a chemical reaction occurring in the bulk in the vicinity of the interface with an interfacial transfer by diffusion and adsorption-desorption processes.     

Correlation between implantation defects and dopants in Fe-implanted SiC

SiC single crystals were implanted with Fe ions and the effects of implantation temperature, Fe concentration, and subsequent swift heavy ion irradiation on both dopant and damage depth distributions were evaluated by using RBS and channelling techniques. It is found that an increase of the implantation temperature above the threshold temperature for amorphization can lead to the formation of a broad layer (∼50 nm) containing a large concentration of implanted Fe atoms (∼2 at.%) but almost free of implantation defects. This particular configuration is likely due to dynamic annealing during implantation combined with defect annihilation at the surface. It is only observed when the implanted species concentration does not exceed a critical value (which lies between 2 and 5 at.% in the present system). Post-implantation swift heavy ion irradiation leads to a further decrease of the damage level, while the Fe distribution is not affected. The Fe substitutional fraction has been evaluated in the different tested conditions. A maximum value of ∼50% is found when implantation is performed at the temperature above that required to prevent amorphization (470 K in the present system). Swift-heavy ion irradiation seems to induce Fe atoms relocation at substitutional positions.     

Profiling the Active Site of a Copper Enzyme through Its Far-Infrared Fingerprint

Vibrations of the metal active site of the Cu,Zn-superoxide dismutase enzyme were analyzed by far-infrared difference spectroscopy and theoretical normal mode calculation. Both electrochemically triggered Cu(I) and Cu(II) redox states show well-defined infrared vibrational modes, notably modes of the histidine ligands, the Cu(II) -His(61) -Zn(II) bridge and of the water pseudo-ligand.     

Raman spectrum of a layer or thin slice at a solid interface

If we use an experimental device with one plane parallel dielectric film and one plane parallel metallic film between two transparent media, we can amplify the luminous energy (homogeneous or inhomogeneous waves) in the dielectric medium, and obtain the Raman spectrum of the film or of a thin slice of 1000 Å thickness.     

Raman scattering of Langmuir-Blodgett barium stearate layers using a total reflection method

In this paper it is shown that the total reflection of a plane wave on a stratified medium of particular configuration provides a very high energy density by means of leaky waves. This property is used to excite the Raman scattering of Langmuir-Blodgett multilayers of about 0.3 μ thick. A comparison is made with other methods and spectra are given.     

Direct Measurement of Electron Beam Scattering in the Low Vacuum SEM

The beam-gas interactions in the low-vacuum SEM is investigated through experimental and simulation approaches. An original experimental way to characterise the skirting is proposed. We obtained directly image distribution of the primary electron beam and the scattered electrons in the low-vacuum SEM. The experimental results are compared to the electron beam profile obtained with Monte-Carlo simulation.