logo_links.gif Aggregation and Kinetics of Reactive Systems


Apl. Prof. Dr. Thomas Zeuch

Georg-August-Universität
Institut für Physikalische Chemie
Tammannstr. 6
D-37077 Göttingen

E-mail: tzeuch1(at)gwdg.de

Phone: +49-551-39 33126

Fax: +49-551-39 33117


Lehre

Zum heutigen (8.3.2021) hundertsten jährlichen Weltfrauentag möchte ich in tiefer Verneigung der ersten Göttinger Apl. Professorin Emmy Noether eine Ausarbeitung widmen, die ein Kondensat ist unserer inwischen jahrzehntelangen Auseinandersetzung mit den mathematischen und physikalisch-chemischen Begriffs- und Modellbildungen, auf der Suche nach den Bindegliedern unserer Forschung und Lehre. Erst am Ende eines langen Weges haben wir begonnen die bahnbrechende Entdeckung Emmy Noethers in ihrer Tiefe zu erfassen. Die damaligen Herren der Schöpfung bezeichneten sie leicht spöttisch aber anerkennend als Invarianten-Prinzessin. Und es sind genau diese Invarianten der Bewegung, die in einer ständig zu maximaler Ausdifferenzierung neigenden Welt verbindende Perspektiven und Orientierung stiften können. Ein zu Emmy Noethers 1918 publizierten "Invarianten Variationsproblemen" komplementärer mathematischer Befund, der auf Legendre zurückgeht, führt zu den "idealen Wegen der Bewegung", die aus unserer Sicht eine konzeptionelle Integration von Thermodynamik, Mechanik und Quantenmechanik erlauben. Wie das gehen kann, ist im verlinkten Text ausgearbeitet.

Ideale Wege der Bewegung

Vortrag über Raum und Zeit in Chemie und Physik


Teaching

On the occasion of the hundredth annual International Women´s Day (8th of march, 2021) we dedicate, in great admiration, Emmy Noether, the first extraordinary female Professor in Göttingen, the elaboration presented in the document linked below. It is a consolidation of my decade-long reasoning about the mathematical and physical-chemical concepts and models that are the building blocks and connecting links of our research and teaching. At the end of a long journey we have just begun to understand the breakthrough discoveries of Emmy Noether in their full depth. She was recognized for her work on invariants among the leading figures in male mathematics in her day. And these invariants of motion are the interconnecting elements that can give orientation and that can open new perspectives in a scientific world that tends to split-up in more and more sub-disciplines. A mathematical observation going back to the work of Legendre paves the way from “Invariant Variation Problems” to ”Ideal Translations for Transitions” that allow in our view a conceptual integration of thermodynamics, mechanics, and quantum mechanics. How this can be achieved is sketched in the linked text document.

Ideal Translations for Transitions

The measurement problem (by S. H.)

Gedankenexperiment/Thought Experiment (by S. H.)


Kritische Gedanken zu Forschung und Lehre (German)

"Wo der Wind der Freiheit weht", ist das deutsche Leitmotiv der renommierten Stanford Universität. Aber will nicht, wer Sprachmuster unter Veto stellt, eigentlich die Gedanken kontrollieren? Und gleicht nicht jede Uni, die Sprachregeln, so gut sie auch gemeint sein mögen, über ihre Mitglieder verhängt, einem geistigen Gefängnis, einer Karikatur ihrer selbst? Heißt es nicht am Anfang war das Wort? Just a thought ...

Research

The research in the aggregation and kinetics group aims at exploring aggregation phenomena under reactive conditions at the molecular level. The atmospheric oxidation of certain organic substances and the oxidation of hydrocarbon fuels in diesel engines are well known processes leading to particle formation. In the atmosphere such aggregates containing a large fraction of organic matter are called secondary organic aerosol. Soot particles are responsible for the black colour of exhaust gas from diesel fuel combustion. Aerosols influence visibility, climate, and human health and their chemistry is an active field of research with many open issues. An example is the climate effect: It is very large but the mechanisms behind are only poorly characterized. In this context an important question is the exact structure of the smallest aggregates at the beginning of aggregation processes. Such small aggregates are called clusters and we examine their structure with the help of reactive sodium atoms. When attached to an aggregate and irradiated by ultraviolet or visible light the weakly bound sodium 3s electron is ejected and the cluster softly ionized without fragmentation. Additional irradiation with an infrared laser provides the infrared spectrum of the aggregate. The infrared spectrum is our basis for examining the cluster structure, but we need support from theory for arriving at structural assignments. When aggregation occurs under reactive conditions a zoo of stable and unstable species is formed and it is very difficult to identify those, which initiate the formation of aggregates. Here our trick is first to study the kinetics of the gas phase chemistry, which we can do well and second to analyze the time evolution of the particle size distribution, which we also can do well. The links we find between gas phase kinetics and the particle dynamics are our key for unravelling the aggregation mechanism. With a newly developed code we can simulate now for sulphuric acid vapour the complete aggregation process from reactive monomer formation in the gas phase to the time evolution of the emerging particle size distribution. Moreover we continuously develop complex reaction mechanisms for model fuels being used in industrial combustion research for optimizing engine performance and minimizing pollutant formation. An important achievment of our work with many cooperation partners is the Cozzareli prize winning paper "The end of ice I".

Members


PhD students

Florian Zurheide
Daniel Becker
Steven Celik

Master students

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Postdoc

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Been here




Publications

open access:

C. C. Pradzynski, C. W. Dierking, F. Zurheide, R. M. Forck, U. Buck, T. Zeuch und S. S. Xantheas, Infrared detection of (H2O)20 isomers of exceptional stability: a drop-like and a face-sharing pentagonal prism cluster, Phys. Chem. Chem. Phys., 2014, 16, 26691.

U. Buck, C. C. Pradzynski, T. Zeuch, J. M. Dieterich, B. Hartke, A size resolved investigation of large water clusters, Phys. Chem. Chem. Phys., 2014, 16, 6859.

L. Seidel, K. Hoyermann, F. Mauß, J. Nothdurft, T. Zeuch, Pressure Dependent Product Formation in the Photochemically Initiated Allyl + Allyl Reaction, Molecules, 2013, 18, 13608.

C. C. Pradzynski, R. M. Forck, T. Zeuch, P. Slavíček, U. Buck, A Fully Size-Resolved Perspective on the Crystallization of Water Clusters, Science, 2012, 337, 1529-1532.

R. M. Forck, I. Dauster, Y. Schieweck, T. Zeuch, U. Buck, M. Ončák, P. Slavíček, Communications: Observation of two classes of isomers of hydrated electrons in sodium-water clusters, J. Chem. Phys., 2010, 132, 221102.

List of publications


Institute of Physical Chemistry (other groups)

School of Chemistry (Fakultät für Chemie)

University of Göttingen

Suhm Group Göttingen


Revised 2021-05-25