Untersuchung und Optimierung von Verfahren zur Herstellung und Charakterisierung von homogenen und heterogenen Fullerenen Schlussbericht

1. State of the art: Using the electric arc method (Kraetschmer) it is possible to produce macroscopic amounts of fullerenes (C_6_0). 2. Motivation: A method suitable for the production of macroscopic amounts of higher fullerenes has not yet been developed. Mass spectra of fullerene samples produced by laser evaporation of graphite show a large number of higher as well as endohedral fullerenes. 3. Method: An apparatus for the production of fullerenes by laser evaporation of graphite has been developed. Basic physical properties of fullerenes have been investigated using fragmentation mass spectroscopy and electron energy loss spectroscopy (EELS). 4. Results: Investigation of the suitability of different laser types for the laser-assisted production of fullerenes; determination of optimum parameters for the production of fullerenes by laser evaporation; production of fullerenes by means of laser evaporation; optimization of the photoionization time-of flight mass spectroscopy for the measurement of fragmentation engergies of fullerenes; investigation of physical properties of fluorinated fullerenes; investigation of physical properties of fluorinated fullerenes; information about fundamental electronic properties of C_6_0; detection of small amounts of higher fullerenes in coalescence experiments. 5. Possible applications: It could be shown that the laser evaporation method is more efficient for the production of higher fullerenes than the conventional arc method. (orig.)Available from TIB Hannover: DtF QN1(40,41) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEBundesministerium fuer Forschung und Technologie (BMFT), Bonn (Germany)DEGerman

VUV photoionization and photofragmentation of large molecules and clusters: polycyclic aromatic hydrocarbons (PAHs), fullerenes and peptides Final science report

The photoionization and photofragmentation of large molecular species is currently a topic of intense research activity. Whereas mass spectrometry has been very successful in its analytical applications for large species such as peptides and proteins, the understanding of the physical chemistry of the processes is still lacking. In the present research effort we have concentrated on three classes of molecules: 1. Polycyclic aromatic hydrocarbons (PAHs) (see reprints 1-7 from the list of publications); 2. Fullerenes (see reprints 5, 8-12) and 3. A small peptide (reprint 13). PAHs are important in interstellar chemistry and in combustion. Fullerenes are a third allotropic form of carbon with unusual chemical and technological properties. The chemistry of peptide radical cations is unique and deserves further study. All of the large molecules offer new and exciting opportunities. (orig.)Available from TIB Hannover: F00B230 / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEGerman-Israeli Foundation for Scientific Research and Development (GIF), Oberschleissheim (Germany)DEGerman

Neue physikalische Wirkprinzipien fuer Hochleistungsfestkoerperlaser. Teilvorhaben: Physikalische Grundlagen der Parallelschaltung von Laserverstaerkern mit Phasenkopplung Forschungsbericht/Abschlussbericht

Available from TIB Hannover: F98B587+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEBundesministerium fuer Bildung, Wissenschaft, Forschung und Technologie, Bonn (Germany)DEGerman