Objective
The main goal of the present project is to use the unique ability of SIMS and SNMS techniques to study the fundamental properties of homogeneous and heterogeneous clusters, which are considered as a suitable basis for the development of new cluster-assembled materials. To generate the mentioned clusters by ion sputtering the use of various samples is considered as well as the use of various projectiles. A special emphasis should be placed on the cooperative character of the project that unites efforts of the involved research teams and allows promising comparisons between sputtered cluster ions and cluster neutrals, between the conventional atomic ion bombardment and the newer cluster ion bombardment as well as between the experimental results and those predicted theoretically.
The present project aims at conducting a set of the following experiments:
measurements of mass distribution of sputtered positive and negative cluster ions as well as neutral clusters;
identification and investigation of fragmentation channels for selected sputtered clusters;
measurements of kinetic energy spectra of cluster ions fragmenting within field-free zones of the mass spectrometers and determination of the Kinetic Energy Release (KER) distributions for the selected sputtered cluster ions;
measurements of kinetic energy spectra of the selected sputtered cluster ions.
The following data processing procedures will be developed:
a special new experimental procedure for the determination of the energy resolution functions and the software for the according correction of measured energy spectra;
improved existing original procedures and the software for the estimation of the cluster fragmentation activation energies from the measured KER-distributions as well as for the determination of the sputtered cluster ion distributions over fragmentation rate constants, lifetimes and internal energies;
a new original procedure considering the use of a secondary ion mass spectrometer as the internal energy filter in the mode of cluster ion fragmentation study.
Moreover, Mollar Dynamics simulations for the calculation of the internal energy distributions of sputtered nascent clusters and a theoretical study of the influence of local electronic excitations generated by the projectiles within the -surface area of solids are also planned to be carried out.
It is expected that present project will provide the following information:
a series of mass spectra of clusters sputtered by atomic and cluster ion bombardment;
the ionization probability of sputtered clusters;
identification of cluster fragmentation channels;
kinetic energy release distributions of fragmented clusters;
a series of kinetic energy spectra of the sputtered clusters;
fragmentation rate dependencies on the time after the cluster (ion) emission;
lifetime distributions of sputtered clusters;
internal energy distributions of sputtered clusters;
activation energies for the selected fragmentation channels.
The relations between all the above mentioned sputtered cluster characteristics and the projectile-sample combinations and the sputtering conditions are expected to be determined. As a main result of the project, the potentialities of the ion sputtering technique to generate so- called super-stable clusters will be explored. For such species, the experimentally determined properties will be compared to those predicted by theoretical ab-initio calculations. Moreover, it is expected that the close interaction between experimental and theoretical parts of the project will significantly propel the interpretation of observed experimental results and, hence, lead to a much better understanding of the fundamental physical processes underlying the formation of clusters in sputtering.
Topic(s)
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2610 Antwerpen (Wilrijk
Belgium