Research Activities at the Faculty

Reports of the Institutes and Departments

Research Activities at the Faculty

Postgraduate Research Units

The aim of the Postgraduate Research Unit is to run an interdisciplinary training project which helps a large number of postgraduates to achieve their doctorate during a three-year period of postgraduate training as part of a complex research programme.

The research programme contains the topics "Interfaces of Porous Solids", "Semiconductor Interfaces" and "Fluid Interfaces". It involves the usage of a representative arsenal of instrumental and theoretical methods, and is devoted to the diversity of physical phenomena and chemical conversions of interfaces of all possible phase combinations.

A postgraduate training programme studying the "Theoretical Fundamentals of Interfaces", "Experimental Methods for the Characterisation of Interfaces" and "Technical and Analytical Applications of Interface Phenomena" as well as a series of colloquia featuring renowned visiting scientists are organised for the doctoral candidates.

The institutions involved include the Institutes of Physical and Theoretical Chemistry, Technical Chemistry, Analytical Chemistry, and Organic Chemistry, as well as the interdisciplinary group Time Resolved Spectroscopy, all of which are based at the Faculty of Chemistry and Mineralogy, as well as at the Institute of Experimental Physics I at the Faculty of Physics and Earth Science, and the Institute of Non-classical Chemistry at the University of Leipzig.

Eighteen professors (who submit the applications), 11 associated professors, six post-docs (four grant-holders and two associated post-docs), 26 doctoral candidates (including 19 grant-holders and seven associated members supported by other funding programmes) make up the research unit. In 2000, 10 doctoral programmes were successfully completed on schedule.

The sub-projects dealt with are listed on --->.

• Postgraduate Research Unit: "Mechanisms and Applications of Non-conventional Oxidation Reactions"
Spokesman: Prof. E. Hey-Hawkins (Institute of Inorganic Chemistry)

Non-conventional aspects of a central chemical reaction, namely oxidation, are studied in an interdisciplinary research group, and form the core of a modern, stimulating postgraduate training programme.

The central aspects of the research programme are the development of new oxidation agents (heterometallic complexes, benzene perselenic acid, bisazidoiodosobenzene, 3-hydro-peroxysultime and sultame, electrophilic amination with a homochiral nitrenoid, O-sulphonyl-oxime and a chloronitroso compound), their application in syntheses, enzymatic oxidation reactions (cytochrome P450, independent and dependent monooxygenases), including the characterisation and structural determination of enzymes, and the study of reactive oxygen species in living organisms and in inflammable processes.

The Postgraduate Research Unit offers scholarship-holders and associate members a research-based training programme which comprises the main chemistry subjects (inorganic chemistry, organic chemistry, physical chemistry), pharmaceutical chemistry, biochemistry (including molecular biology), biophysics and environmental chemistry. Hence, in addition to the topic of their own dissertation, scholarship-holders and associate members undergo further interdisciplinary training. The training programme includes lectures, colloquia with prominent visiting scientists, a programme of seminars, and practical courses in the laboratories of the groups involved.

Thirteen professors and Habilitation candidates, one post-doc, 10 scholarship-holders and nine associate members from the Faculty of Biology, Pharmacy and Psychology, the Faculty of Chemistry and Mineralogy, and the Faculty of Medicine form the Postgraduate Research Unit.

The research projects dealt with are listed on --->.

Collaborative Research Centre

Collaborative Research Centre 294: "Molecules in Interaction with Interfaces"
Spokesman: Prof. D. Michel (Faculty of Physics and Earth Science, Institute of Experimental Physics II)

Sub-project D1:
Studies of elementary steps of heterogeneous catalysis – elucidation of the reaction mechanism of n-butene-isomerisation on ferrierite and similar zeolites.
Head: Prof. H. Papp (Institute of Technical Chemistry)

The mechanism of isomerisation of n-butene to i-butene on zeolites is the subject of controversial discussion. Initial findings show that a mainly mono-molecular mechanism takes place on ferrierite, whereas on ZSM-5 zeolites the dimerisation of iso-Butene to C8-hydrocarbons occurs in a subsequent reaction.

Centre of Excellence

Centre of Excellence: "Chemical Signal and Biological Answer"
Spokesman: Prof. P. Welzel (Institute of Organic Chemistry)

This Centre of Excellence was funded by the DFG (National German Research Society) from 1 January 1996 to 31 December 2000. It was run by a team from three faculties (Chemistry and Mineralogy; Biology, Pharmacy and Psychology; Medicine).

The scientific objective was to improve the understanding of the interaction between active ligands (chemical signals) with their targets, which are usually based on highly selective recognition mechanisms. Funding totalled DM 7.07 million.

According to a final appraisal by the DFG at a meeting in March 2001 (2/3 February 2001) the Centre of Excellence was very successful in:

• Establishing an inspiring scientific atmosphere in the interdisciplinary area of chemistry and biosciences with important impacts on research and teaching structures, the joint use of expensive instruments, joint research proposals, and the organisation of meetings
• Organising conferences (19 meetings and symposia)
• Taking part in the acquisition of the following instruments: MALDI-TOF mass spectrometer, CD spectrometer, 600 MHz NMR spectrometer, 7 Tesla Ion cycloresonance mass spectrometer, ConfoCor, BIACORE
• Inviting scientists from Germany and abroad to give lectures (altogether 63 invitations from both academic institutions and industry)
• 166 publications presenting findings obtained within the framework of the Centre of Excellence were either published or submitted for publication
• Scientists of the Centre of Excellence gave altogether 170 lectures at other universities, at symposia or at meetings held by the Centre of Excellence
• 29 graduate students working in the Centre of Excellence obtained a PhD, while 19 more are still working on topics supervised by the Centre of Excellence
• Three members of the Centre of Excellence completed their Habilitation; two of them have already received university appointments elsewhere

For more details, see:
http://www.uni-leipzig.de/~inno/innokoll/index.htm

Centre of Excellence: "Phenomena at Miniaturisation Limits"
Spokesman: Prof. W. Grill (Faculty of Physics and Earth Science, Institute of Experimental Physics II)

Sub-project K: Dimension Quantisation in III-V-Heterostructures
Researchers: Dr V. Gottschalch, Dr R. Schwabe, PD Dr B. Rheinländer, PD Dr R. Pickenhain, G. Kirpal, Dr H. Schmidt, T. Hofmann, F. Kasic, J. Kovac, M. Schubert, G. Wagner, G. Benndorf

The project focuses on the study of MOVPE monolayer epitaxial growth of AlAs, GaAs, InAs, InP and GaP in various AIII-BV-barrier materials. The localisation energies of the monolayers grown in different host materials have been obtained by applying photoluminescence, ellipsometry, deep-level transient spectroscopy and photocurrent spectroscopy. These results were supported by pseudopotential supercell calculations performed for several of the monolayer/barrier material combinations grown. Semiconductor lasers with monolayers or short-period superlattices in the active area have been successfully tested.

Period of funding: January 1996 – December 2000

Sub-project L: III-V-semiconductor Microresonators with Ultra-thin Isovalent Layers
Researchers: PD Dr B. Rheinländer, Dr V. Gottschalch, S. Hardt, J. Kvietkova, J. Kovac, L. Kuna

This project studies the coupling of resonator modes with excitation states in individual and multiply repeated isovalent atomic layers in AIII-BV-semiconductor microresonators.

The active region of the samples grown by metal organic vapour phase epitaxy consists of InAs monolayers separated by GaAs barriers. The active region is embedded in a 3.25- Al0.3Ga0.7As microcavity with a Al0.2Ga0.8As/AlAs Bragg mirror on the bottom. Edge-emitting oxide-stripe lasers made from these structures exhibited significantly lower threshold current densities and a lower temperature-dependence of the emission wavelength compared to similar Lasers without the vertical cavity.

Period of funding: July 1998 – December 2000

Interdisciplinary Semiconductor Research Team

FAHL – Leipzig Interdisciplinary Semiconductor Research Team
Head: Prof. K. Bente (Institute of Mineralogy, Crystallography and Materials Science)

Methodological co-operation (HRTEM) with the Centre of Excellence "Phenomena at Miniaturisation Limits".

Leipzig-Halle-Jena research collaboration

Leipzig-Halle-Jena research collaboration

Co-operation and complementarity in research and methodological equipment in the field of mineralogy in higher education.

EU-funded research project

EU-funded research project: Thematic Network "Glow Discharge Spectroscopy for Spectrochemical Analysis"
Head: Prof. J. A. C. Broekaert (Institute of Analytical Chemistry)

The project studies the possibilities of glow discharge in particular with respect to its usage for the analysis of environmentally relevant samples and the analysis of new materials. Work focuses on analysing ceramic powders using plasma spectrometry (Leipzig) and glow discharge (IFW e.V., Dresden), as well as the determination of environmental pollutants in co-operation with the University of Oviedo (Spain).

Period of funding: 1 January 1999 – 31 December 2001

EU-funded research project: "Aldehydes"
Head: Prof. W. Engewald (Institute of Analytical Chemistry)

The simultaneous trace determination of aldehydes and ketones in various environmental matrices is mainly carried out using the DNPH method, in which the carbonyl compounds are converted into the corresponding hydrazones in the presence of acid with 2,4-dinitrophenylhydrazine, and then determined using HPLC.

Involving nine partners from six different countries, the aim of this EU project is to overcome the existing weak points of this technique stemming from interference with ozone or nitrogen oxides, as well as from the diversity of possible unsaturated carbonyl compounds. The Leipzig team is developing and testing a gas-chromatographic method of determination independent of HPLC involving the usage of new dosing techniques.

Period of funding: December 1997 – November 2000

TMR: EU-funded research project: Fluorine as a Unique Tool for Engineering Molecular Properties
Head: Prof. K. Burger (Institute of Organic Chemistry)

The development of synthetic methodology for the regioselective introduction of fluorine or short-chain perfluoroalkyl groups into organic molecules is of current interest. Fluoromodification often confers unique properties on a molecule, e.g. in terms of increased metabolic stability and lipophilicity, which in turn optimises in vivo absorption and transport rates. As a consequence, the pharmacokinetic profiles are often improved.

The six partner laboratories participating in this network chose the following classes of natural products for fluoromodification: steroids, carotinoids, terpenes, carbohydrates and peptides. Furthermore, one project deals with new polyfluorinated materials, namely the preparation of new fluoromodified membranes for selective gaseous and liquid separation as well as new fluorinated materials with low surface energy for use as anti-adhesive coatings.

Period of funding: December 1998 – November 2001

DFG priority programme

DFG priority programme: "Fundamentals of Electrochemical Nano-technology"
Head: Prof. U. Stimming (Munich Technical University, Chair of Energy Process Engineering)

Sub-project:
Scanning Probe Microscope Manipulation and Characterisation of Electrocatalytic Centres
Researchers: Dr G. Wittstock, Prof. R. Szargan (Wilhelm Ostwald Institute of Physical and Theoretical Chemistry)

The aim of the project is to study electrocatalytic reactions on individual reactive centres with dimensions in the nanometre range. This is carried out using an instrument we are currently developing which combines the operation of a scanning tunnelling microscope in an electrolyte environment (ECSTM) and a scanning electrochemical microscope (SECM) quasi-simultaneously. This device should enable local reactivity information to be assigned to individual topographical features. The model systems to be investigated using this instrument are based on ordered alkane thiol layers on gold surfaces in which shortcomings are induced by means of co-adsorption, sequential occupation or the STM peak. These defects are intensified using metal precipitation. Depending on the type and size of the precipitated metal clusters, structures with differing reactivity occur. Some of the clusters produced in this manner are dissolved again by means of oxidation agents produced on the SECM probe. Individual catalytic centres are prepared by combining these strategies. They are then characterised – with STM in terms of their topography and with SECM with respect to their reactivity.

Period of funding: 29 September 1997 – 29 September 2001

DFG priority programme: "Structure Gradients in Crystals"
Head: Prof. Schmahl (Institute of Mineralogy, University of Bochum)

Sub-project:
Modelling of diffusion-induced segregations in structure gradients
Researchers: Prof. K. Bente (Institute of Mineralogy, Crystallography and Materials Science), Prof. St. Luckhaus (Mathematical Institute) in co-operation with Prof. St. Müller (Max Planck Institute of Mathematics in the Sciences)

Since 1 October 1998

DFG interdisciplinary research project "Interfaces on Oxides"
Co-ordinator: Prof. H. Neddermeyer (Chair of Experimental Physics, University of Halle-Wittenberg)

Sub-project A3:
X-ray emission spectroscopy of transition metal oxide layers using synchrotron radiation
Researchers: Prof. R. Szargan, Prof. T. Chassé (Wilhelm Ostwald Institute of Physical and Theoretical Chemistry)

The aim of the project is to investigate the local electronic structure of epitaxially grown ultrathin multilayers of 3d metal oxides at the interfaces between metals and metal oxides in buried layer structures: charge transfer phenomena, d-d excitation channels, and gap parameters.

Period of funding: July 2000 – July 2002

BMBF interdisciplinary project

BMBF interdisciplinary project: "Instrumentation for X-ray Fluorescence Spectroscopy with Synchrotron Radiation"
Co-ordinator: Prof. R. Szargan (Wilhelm Ostwald Institute of Physical and Theoretical Chemistry)

This project (for which funding has been granted) covers the instrumentation for X-ray emission spectroscopy with angle-resolved and energetically variable excitation and angle-resolved registration, which in combination with a device for recording X-ray absorption spectra and a preparation chamber is designed to open up new applications for intensive X-raying using a third-generation synchrotron source such as BESSY II. The advantages of angle-resolved and polarisation-resolved X-ray emission spectra (element-, edge- and symmetry-specific as well as resonant excitation and an impressively large emersion depth) are to be used by the co-operating users of the participating university institutes (Berlin, Dresden, Leipzig, Würzburg) as well as research establishments of the Max Planck and Leibniz Societies to investigate characteristic phenomena during resonant photoemission and to determine local partial state densities and orbital symmetries. The aim of the work is to produce new types of information on the geometrical and electronic structure of highly ordered ultra-thin layers on metal and semiconductor substrates, on the interface structure of buried layers in semiconductor material, and the electron structure of highly correlated materials.

Summary

The research findings achieved in 2000 have been published in scientific journals (see list of scientific publications), summarised in theses (two Habilitation theses, and 33 doctoral theses; see list of dissertations), and presented at congresses, symposia and colloquia. For more detailed information, please see the 2000 Annual Report of the Faculty of Chemistry and Mineralogy.