- Diploma, Chemical Engineering,National Technical University, Athens, 1974
- Ph.D., Chemical Engineering, Stanford University,1980
Research in the area of experimental solid surface science is carried out on a time-sharing basis with other faculty members in the Surface Science Laboratory (SSL). The central theme of the research is the use of a large variety of surface analysis and characterization techniques in order to determine the structure, composition and electronic properties of the outermost atomic layers of solid materials exposed to ultra-high-vacuum or controlled gaseous atmospheres and correlate them with the material behavior in various processes. Surface and interface analysis is of primary importance in both fundamental and applied research in the field of Material Science and Technology. Outstanding demonstration of the significance of modern Surface Chemistry research in technological areas such as those described above is the 2007 Nobel Prize for Chemistry, which was awarded to Prof. Gerhard Ertl for his groundbreaking studies of chemical processes on solid surfaces. A number of surface sensitive techniques, including X-ray and ultra-violet photoelectron and Auger electron spectroscopies (XPS/XAES, UPS), Auger Electron and Electron Energy Loss Spectroscopy (AES, EELS), Ion Scattering Spectroscopy (ISS), work function measurement (WF) and Low-energy electron diffraction (LEED), as well as traditional mass spectrometric techniques like temperature programmed desorption (TPD) are available in the SSL. In addition, there is access to synchrotron radiation facilities, in which high-resolution photoelectron spectroscopy (SRPES) and additional techniques can be implemented, including near-edge and extended X-ray absorption fine structure analysis (NEXAFS/ SEXAFS/ EXAFS). The laboratory started its activity in 1991 as a research group at the Department of Chemical Engineering, U. Patras (DChe/UP ). In 2002 SSL was officially established as a distinct Research Laboratory at DChe/UP and since then it places also emphasis on applied research and surface analytical services to other public and private organizations as well as to the industry. Recently, SSL (UPatras) was a partner in the EU-funded project ANNA (ANNA), which aimed at creating a European Integrated Multi-site Laboratory Facility for Nano- and Micro-Electronics Analysis. In the frame of this project, SSL has obtained Accreditation according to ISO17025 for Surface Analysis via XPS ( ESYD, Certificate No 660, 12 March 2010). Some of our past and current research topics are summarized below.
Model catalytic experiments on single crystals.
The use of single crystals as model catalysts for adsorption and surface reaction studies allows a detailed correlation of the adsorptive and catalytic activity with the surface structure and electronic properties of the catalyst. Recent examples of our research in this area include the study of surface alloying on the Sn/Ni(111) system and its effect on CO adsorption, in collaboration with Charles University(Prague) and the Synchrotron Radiation Facility ELETTRA (Trieste).
Study of realistic model catalysts.
The use of single crystal or flat polycrystalline oxides and metals as substrates for the preparation of layered or particulate deposits by evaporation in ultra-high-vacuum constitutes a model system for supported catalysts. These so-called realistic model catalysts are subject to adsorption and surface reaction studies allowing a correlation of the adsorptive and catalytic activity with the size, surface structure and electronic properties of the catalyst particles. Recent examples of our research in this area include: (1) the study of realistic models of Ziegler-Natta catalysts ( evaporation of Ti and MgCl2 on Si, Ti and SiO2 substrates) in collaboration with FORTH-ICE/HT (Patras) and ELETTRA(Trieste) , (2) The study of the Ni-Cr bimetallic system on NiO(100) with XPS and molecular dynamics simulations, in collaboration with the Physics Department, U. of Ioannina.
Spectroscopic characterization of various materials.
This current activity includes, on the one hand the development of versatile computational methods for the advanced quantification of XPS and the extraction of specialized information for surface nanostructures (e.g. individual film thickness and composition of nanofilm stacks) and on the other hand the application of XPS and other surface analysis and characterization techniques on particular specimens (e.g. catalysts, biomaterials or refractory materials and thin films thereof). These specimens are provided by collaborating groups within and outside the Department and are also studied in the frame of offering Surface Analysis Services to third parties via the Research Committee of the U. of Patras. The aim is the elucidation of certain aspects of the material behaviour (e.g. adsorptive/catalytic properties) or the determination and understanding of the influence of various preparation parameters on the quality of the material (e.g. crystallinity, impurity content, interface reactions).
“The adsorption and catalytic oxidation of CO on evaporated Pd particles”
S. Ladas, H. Poppa and M. Boudart,
Surface Sci., 102, 151 (1981).
“Kinetic oscillations and facetting during the catalytic CO oxidation on Pt(110)”
S. Ladas, R. Imbihl and G. Ertl,
Surface Sci., 198, 42 (1988).
“Origin of Non-Faradaic Electrochemical Modification of Catalytic Activity”
S. Ladas, S. Kennou, S. Bebelis and C.G. Vayenas,
J. of Phys. Chemistry , 97, 8845 (1993).
“Interfacial oxidation of ultra-thin Ni and Crfilms on yttria-stabilized zirconia”
O.Khyzhun, L.Sygellou, S.Ladas,
J. Phys. Chem. B , 109, 2302 (2005).
“On the origin of the substrate induced oxidation of Ni/NiO(001) studied by X-ray
Photoelectron Spectroscopy and Molecular Dynamics Simulations”
E.Symianakis , G.A. Evangelakis, S.Ladas,
Surface Sci. , 604 , 943 (2010).
“The interfacial properties of MgCl2 thin films grown on Ti(0001)”
S.Karakalos, A.Siokou, F.Sutara, T.Skala, F.Vitalyi, S.Ladas, K.Prince, V.Matolin, V.Chab ,
J. Chem. Phys.., 133 , 074701-1 (2010) , [doi:10.1063./1.3473933].
“An X-ray photoelectron spectroscopy study of strontium-titanate-based high-k film stacks”
L.Sygellou, H. Tielens, C.Adelmann, S.Ladas ,
Microelectronic Engineering, 90, 138 (2012).