FU Berlin Digitale Dissertation
Gero Heusler : Gas phase investigations of geometry and charge transfer of carbon clusters Gasphasenuntersuchungen zu Geometrie und Ladungstransfer von Kohlenstoffclustern
|Abstract| |Table of Contents| |More Information|

Abstract Carbon clusters have been investigated in the gas phase. A new modular molecular beam apparatus has been set up and allows a variety of experiments. This work divides up into three parts: In the first part, it is shown that the near-resonant charge transfer reaction C60 + Na(3p) --> C60- + Na+ exhibits an extraordinary large alignment effect (< rss > = 0.8 ± 0.2). In a crossed beam experiment, the sodium is excited using a linearly polarized two mode dye laser. The alignment effect is observed by simultaneously monitoring the dependence of the fluorescence and the C60- anions on the polarization direction. It is found that practically only sodium atoms with their electronic charge cloud asymptotically aligned along the relative velocity vector lead to charge transfer. The clear effect is interpreted in terms of the "orbital following" model and the strong p-character of the LUMO (lowest unoccupied molecular orbital) of C60. The second part is dedicated to a mass spectrometric characterization of the carbon clusters. Carbon clusters are produced by laser-vaporization and subsequent supersonic expansion. It turns out that the bimodal distribution of carbon cluster cations may even be trimodal. This third mode is explained by the coalescence of smaller fullerenes in the source. The studies using reactive carrier gases (hydrogen and nitrogen) give some insight in the variety of the geometries of carbon cluster cations. Evidence for the formation of long-lived, excited neutral states in large fullerenes is presented. In the third part, the geometries of the carbon cluster cations are investigated using the technique of gas phase ion chromatography. The mobility of the ions in an inert gas is determined. A comparison with the simulated mobilities of different geometric isomers allows a structural assignment of the different isomers. This will allow future studies of the reactivity of carbon clusters in dependence on their geometry.

Table of Contents Download the whole PhDthesis as a zip-tar file or as zip-File For download in PDF format click the chapter title Inhaltsverzeichnis 1 Einleitung 2 Experimenteller Aufbau I. Ladungstransfer: Die Reaktion C60 + Na(3p) --> C60- + Na+ 3 Theoretische Einführung 4 Meßergebnisse und Datenanalyse II. Massenspektrometrische Untersuchungen 5 Massenspektrometrische Analyse der Kohlenstoffcluster 6 Hochangeregte Neutralcluster langer Lebensdauer? III. Geometrie der Kohlenstoffcluster 7 Mobilität und Diffusion von Ionen in Gasen 8 Messungen der Mobilität von Kohlenstoffclustern 9 Zusammenfassung und Ausblick 10 Literaturverzeichnis

More Information:
Online available:	http://www.diss.fu-berlin.de/1999/27/indexe.html
Language of PhDThesis:	german
Keywords:	fullerenes; carbon clusters; charge transfer; alignment; geometry; gas phase ion chromatography; mobility
DNB-Sachgruppe:	29 Physik, Astronomie
Classification PACS:	36.40.-c, 34.70.+e, 32.80
Date of disputation:	12-May-1999
PhDThesis from:	Fachbereich Physik, Freie Universität Berlin
First Referee:	Prof Ingolf Volker Hertel
Second Referee:	Prof Ludger Wöste
Contact (Author):	Heusler@mbi-berlin.de
Contact (Advisor):	Hertel@mbi-berlin.de
Date created:	05-May-1999
Date available:	03-Jun-1999

 

---

|| DARWIN|| Digitale Dissertationen || Dissertation|| German Version|| FU Berlin|| Seitenanfang ||

---

	Fragen und Kommentare an: darwin@inf.fu-berlin.de
© Freie Universität Berlin 1999