Date and place of birth: August 29, 1952, Riga, Latvian Republic Marital status: Married, one daughter Place of work: Institute of Solid State Physics, University of Latvia Present position: Head of Laboratory, Senior Researcher Address: Kengaraga street 8, LV-1063 Riga, Latvia Phone: (+371) 67251691 FAX: (+371) 67132778 E-mail: purans@cfi.lu.lv EDUCATION
ACADEMIC AND PROFESSIONAL EXPERIENCE
PROFESSIONAL ACTIVITIES, FELLOWSHIPS
Research supervisor of National research programmes:
Research supervisor of International research programmes:
Participation in International scientific programmes: Italy - 1982, 1983, 1986, 1988 - 1993 LNF INFN Frascatti (Roma). "EXAFS study of electrochromic and superionic oxides" Advisor Prof. E. Burattini; "EXAFS study of BaBiPbO3 oxides and glasses" Advisor Prof. A. Baldzarotti; "Multiple - Scattering effect in ReO3" Advisor Prof. C.R.Natoli. USSR - 1984, 1986, 1988 programme on synchrotron radiation, Institute of Nuclear Physics AS Novosibirsk. Advisor Prof. G. Kulipanov. USSR - 1988-1991 (Responsible of EXAFS part) "EXAFS spectroscopy with SR". USSR National Project on SR (Zelenograd (Moscow) - Advisor Prof. M. Kovalchuk; France - 1995-1997 PECO CEE LURE (French National SR Laboratory, Orsay) (Responsible of part of International Project). "In-situ XAFS study of transition metal oxides". PECO International (CE) project on applying of synchrotron radiation. Advisor Dir. Ad. H. Dexpert. Italy - 1996 - 1998 INFM Universita di Trento (Italy) "Local structure and anharmonic properties of crystalline Ge" Advisor Prof. G. Dalba. Member of the: - Head of Latvian Synchrotron Radiation Society 1997-present - European Synchrotron Radiation Society Committee, 1993-1996 - Synchrotron Radiation Committee of Zelenograd, 1988-1993 - Latvian Physics Society, 1991-present - Association of Latvian Scientists, 1991-present RESEARCH SUPPORT AND AGENCY 1993 International Science Foundation travel grant 1994-1996 International Science Foundation - LV 8001 and LJ 8001 1994-1997 PECO International (CE) project - LURE (Orsay) SCIENTIFIC ADVISOR Alexei KUZMIN - was awarded the Academia European Baltic Prize for a young scientists in 1996 for the work "X-Ray Absorption Spectroscopy Study of Transition Metals Oxide Compounds and Related Materials". Alexei KUZMIN - Ph.D. in Physics - 1992, LU Riga, "Study of 4d and 5d transition metals oxide compounds by X-ray absorption spectroscopy"; Vera BARANOVA - MSc in Physics - 1989, LU Riga, "Optical emission spectroscopy of silicide sputtering process". Alexei KUZMIN - MSc in Physics - 1989, LU Riga, "EXAFS and XANES of tungsten oxides"; Armand PLATE - MSc in Physics - 1988, LU Riga, "Properties of the amorphous silicon prepared by magnetron sputtering"; Gints KARKLINS - MSc in Physics - 1987, LU Riga, "Optical emission spectroscopy of magnetron sputtering process".
TEACHING EXPERIENCE During last ten years I lectured in the University of Latvia at both undergraduate and graduate levels giving courses on "Structural methods in condensed matter characterization" and "Synthesis, properties, and application of thin films". Also I was invited as associated Professor at French (Paris-Sud, Marseille, Bordoaux I, Amiens) and Italian (Trento, Rome) Universities and gave a lectures on XAFS spectroscopy and a course on "X-ray absorption fine structure data analysis". I have supervised 12 B.S. and M.S. theses and two Ph.D. theses.
RESEARCH INTERESTS My scientific activities are concerned with the X-ray absorption spectroscopy (XAS) study of condensed matter: experimental and theoretical research on local atomic structural and dynamical properties, breaking the pico-metre barrier (10-12 m) in XAS, e.g. research at the picoscopic (10-2 Å) and subpicoscopic (10-3 Å) scale. The research activity is carried out in collaboration with several Synchrotron Radiation Facilities: PWA and PULS at ADONE (Frascati), LURE DCI and SUPER ACO (Orsay), VEPP-3 (Novosibirsk), DESY-HASYLAB (Hamburg), ESRF (Grenoble). Results of simultaneous in-situ and ex-situ x-ray absorption fine structure (XAFS) measurements using hard (metal K- and L-edges) and soft (O K-edge) synchrotron radiation on different transition metal (TM) and rare-earth metal (RE) edges (HxWO3-MoO3, NiO-MgO, WO3-ReO3, WO3-NiO, and CeO2-TiO2) show that this method is very well-suited to study the mixed TM:TM and RE:TM oxides and to follow their phase transitions. We use the excellent sensitivity of the method to probe local (short and medium range order) rearrangements in the several nearest coordination shells around absorbing center and changes in the electronic structure of the TM, RE ions during reduction/oxidation processes in a wide range of temperatures (4 - 800 K). I apply the EDA (EXAFS Data Analysis) software package, developed in my XAS group by Dr. A.Kuzmin, that include the standard (non-linear best fit analysis with the cumulant expansion etc.) and original methods for the analysis of the XAFS of crystalline and disordered materials. The package allows to reconstruct the radial distribution functions (RDF) around an absorbing center with a picoscopic resolution without any prior assumption on the RDF shape. Besides the XAFS signals can be analyzed in terms of single scattering (SS) and multiple scattering (MS) contributions. The EDA package was successfully applied to the analysis of below mentioned materials allowing to determine a set of structural parameters and RDFs for the local environment of several metal ions. I study the role of the focusing and superfocusing (MS) effect in the formation of XAFS is considered for cubic ReO3, non-stoichiometric tungsten oxides WO3-x and FeF3 having the perovskite-type structure. Using an ab initio multiple-scattering approach two cases are mainly analysed: (1) MS effect in ReO3 and WO3-x crystals and (2) high-order superfocusing effect in Me-O(F)-Me-O(F)-Me atomic chain. For all main structures (MoO3-WO3 oxides and MoO3nH2O hydretes) we have done MS calculations on the basis of the X-ray structural data and we have used the full XAFS signals and there characteristic Fourier transforms up to 6 Å as a fingerprints of the different phases. I carry out the experimental research on advanced materials for electrochromic application obtained by vacuum deposition techniques (mainly DC multi-target sputtering) and I develop the plasma Optical emission spectroscopy (OES). Multi-target and multi-magnetron sputtering techniques can be more versatile, and widely applicable, as techniques can be applied to nearly any TM:TM and RE:TM meatal composition, opening up the perspective of the generation of new nonstructural thin films. MAIN FIELD OF RESEARCH AT PRESENT: X-ray absorption spectroscopy:
Local atomic and electronic structure, dynamics and phase-transitions of transition metal oxides:
Advanced materials for electrochromic application:
Local atomic and electronic structure, dynamics of disordered materials and bio-inorganic molecules:
As a result of this study, we have obtained the original information on: 1) the nature of hydrogen insertion in TM oxides; 2) the local structure of amorphous-nanocrystalline oxides and glasses with octahedral structural units; 3) the nature of phase transitions in perovskite-like and layered-like compounds with octahedral structural units; 4) the nature of the atomic rearrangement during small-polarons formation in mixed valence compounds; 5) the nature of the atomic rearrangement around optically active RE ions in b ¢ - and b ² -aluminas exchanged crystals; 6) the nature of the MS processes in compounds based on octahedral structural units; 7) the local structure of TM and RE aquaions and bioinorganic molecules (GdDOTA, Cu(BiK), etc.).
I am the author and co-author of more than 160 scientific publications (the list of recent publications from 1991 to present), which were published in the leading international and soviet journals. |