Cluster formation, stability and structure
The Laboratory is occupied with several ion sources able to produce of a wide range of clusters types and compositions. Systematic studies on the stability and the structure of metal doped noble gas clusters have been performed by changing the composition of these species and studying the “magic numbers” patterns appearing in the mass spectra. Furthermore, we have developed and applied packing models and molecular dynamics simulations which explain the observed stability of the clusters. Our studies provide the first example of structural transitions observed in small cluster systems.
Moreover, gas phase synthesis diagnostic studies on novel molecules with technological interest have been performed: e.g.
Optical properties of mass selected clusters
The technique of photofragmentation spectroscopy of mass selected ions in a reflectron Time-Of-Flight spectrometer has been applied to measure the optical properties (absorption spectra) of prototype weakly bonded complexes. The spectroscopic constants obtained have been used to prove theoretical models of electrostatic interactions and also to improve basis sets for ab initio calculations. The optical absorption of the clusters as a function of their size has been measured and the absorption spectra have been explained for the first time by applying theoretical models (in collaboration with several theoretical groups : S. Farantos,-IESL GR, S. Xantheas-PNNL, Richland USA , M. Mühlhäuser –University of Bonn-D)
The interaction of cluster ion beams with atoms (instead of photons) leads to a series of ion molecule reactions, giving important information for the cluster dynamics, structure and reactivity.
Using a beam-gas cell experimental configuration, the collision induced dissociation (CID) of the clusters is studied and fragmentation cross sections are measured as a function of the cluster size.
Furthermore, we have recently developed a crossed molecular beams arrangement where cluster atom scattering can be investigated including measurements of: CID, beam attenuation (integral Cross section), Angular distribution of scattered ions (Differential cross section) and Energy transfer (double differential cross section)
Nanostructured materials produced by laser ablation in liquids in conjugation with biomolecules
The object of this project is the formation of metallic or metal oxide bionanoconjugates (BNC’s). The BNC’s are functionalized nanoparticles (NP’s), attached to biomolecules. Others as in the chemical synthesis of NP’s in the presence of a capping ligand, the formation method employed here is based on laser ablation of the metal or metal oxide immersed in an appropriate liquid medium (solution). The biomolecules (or other species that will subsequently react with the biomolecules) are present in the solution and will act as capping agent, preventing the agglomeration of the formed nanoparticles and stabilizing the obtained colloid. BNC’s have applications in food, chemical, pharmaceutical industry, agriculture, biochemical applications or sensors.
This project is performed in collaboration with Centre of Advanced Research in Nanobioconjugates and Biopolymers, Iasi, Romania
Combining Laser-Induced-Breakdown-Spectroscopy and Mass-Spectrometry
Our efforts target to enhance the capabilities of Laser Induced Breakdown Spectroscopy (LIBS) by combining optical emission spectroscopy with simultaneous mass analysis (Time-of-Flight Mass Spectrometry, TOF-MS) instrumentation, which yields complementary isotopic analysis and identification of molecular fragments, thus, enabling complete structural and compositional characterization.
Such combined studies are applied for the analysis of the composition and structure of cultural heritage materials due to their major importance to historians and conservators.
Spectroscopy for quality wines
Application of Uv-Vis and fluorescence spectroscopy to analyze wines by monitoring the spectroscopic fingerprints through the entire manufacturing process from grapes to the final product. Comparative studies with other traditional or modern quantitative spectroscopic techniques and correlation of results with statistical analysis are necessary to obtain valuable information about the state of the sample.
This project is performed within the framework of a “Thales” program in cooperation with other laboratories of the University of Crete (NMR, GC-MS) and the Technological Educational Institute of Crete (FTIR).