Spectroscopie d'émission des produits de pulvérisation de solides soumis à un bombardement ionique

Emission spectroscopy of particles sputtered from solids under ionic impact

• Auteur / Autrice : Abdelilah Kaddouri
• Direction : Paul-Guy Fournier
• Type : Thèse de doctorat
• Discipline(s) : Physique
• Date : Soutenance en 1989
• Etablissement(s) : Paris 11

Mots clés

Mots clés contrôlés

Irradiation

Alliages

Pulvérisation

Bombardement ionique

Mots clés libres

Krypton ion

Luminescence

Résumé

À l'aide d'un appareil entièrement construit au laboratoire, nous avons mesuré des longueurs d'onde, entre 190. 0 et 600. 9 nm, et les intensités des émissions lumineuses produites lors de la pulvérisation d'un solide bombardé par des ions Kr+ de 5 keV. Les spectres optiques observés consistent en une série de raies qui dans un certains cas sont superposées à un continuum. L'examen des raies spectrales permet une identifiaction directe des divers produits désorbés de la surface bombardée. Les études menées portent sur : 1) effet des différents paramètres expérimentaux sur les émissions lumineuses ; 2) enregistrement des spectres de luminescence de plusieurs cibles à un seul constituant qui serviront de spectres étalons ; 3) influence de la présence d'oxygène sur l'intensité des raies spectrales ; 4) analyse élémentaire d'échantillons multi-éléments (alliages et composés) ; 5) étude des émissions lumineuses d'un échantillon supraconducteur, YBaCuO₈-₆(δ=1. 74), à température ambiante et à basse température (< 10 K) ; 6) détermination des concentrations des constituants dans des alliages binaires. L'origine des particules excitées responsables des émissions lumineuses est discutée essentiellement à l'aide d'un modèle basé sur l'échange d'électrons entre les particules pulvérisées et la surface.

During ion-bombardment of solids, secondary processes occur such as reflection of projectiles, sputtering, electron emission and emission of electromagnetic radiation. This thesis presents an extensive review of beam induced light emission experiments, and describes a variety of elementary and quantitative analyses. For this purpose, a specific apparatus was built and luminescence spectra of a large number of metals, semiconductors, alloys, compounds, and compacted powders were studied. In addition, a BaYCuO₈-₆(δ=1. 74) superconductor sample was bombarded, both at room and low temperature (≈ 4 K). Typical optical spectra consist of a series of sharp lines, in some cases superimposed on a broad continuum. The line spectrum can easily be identified as emission from excited target atoms or ions. The radiation provides a method for identifying atoms sputtered from a surface, and serves as the basis of a sensitive surface analysis technique. The analytical capability of this method, called ASSO (Analyse de Surface par Spectroscopie Optique) has successfully been tested. When the cleaned sample is exposed in situ to 10ˉ⁵ torr of O2, the optical spectrum shows the same lines, but some of them are enhanced, some remain constant, and others decrease in intensity upon oxygenation of the surface. A systematic study of the influence of oxygen on the light emission has been carried out for Al, Cu, Fe, and Ni targets. The quantitative analysis have been tested on binary alloys. The observed intensity ratio of two constituents in a particular sample is directly proportional to the concentration ratio of the constituents. This result has been also tested when 10ˉ⁵ torr of oxygen was introduced into the target chamber. The question of whether the excited sputtered atoms are indeed responsible for the observed line spectra is discussed. The results are interpreted in terms of a model of resonant electron-transfer combined with oxygen-induced changes in band structure, where the measured yield is governed by electron transfer processes between the excited sputtered atoms and electronic levels in the solid. Experiments designed to clarify the source of the observed continuum radiation have been carried out in this laboratory. One of the major problems in explaining continuum emission is that the spectra of the species which might be proposed as the emitters are very often unknown in the spectroscopic literature. However, ASSO could become a very useful light source for the spectroscopic study of molecules and free radicals which are difficult to generate in the gas phase by other methods. Because of its sensitivity as a surface probe, and because of its simplicity, it seems likely that the ASSo technique will become an important tool for surface analysis with application to scientific, technological, and environmental problems.