Berlin 2005 – wissenschaftliches Programm
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MO: Molekülphysik
MO 22: Poster I
MO 22.7: Poster
Samstag, 5. März 2005, 10:30–12:30, Poster HU
Fragmentation dynamics of polycyclic aromatic hydrocarbons — •Adalbert Ding, Christian Lenski, and Michael Lenski — Technische Universität Berlin, Optisches Institut, Sekr. P1-1, Strasse des 17. Juni 135, D-10623 Berlin
Most favoured theories concerning diffuse interstellar bands propose that the observed radiation originates from infrared fluorescences of vibronic highly excited polycyclic aromatic hydrocarbons (PAHs).
Photodissociation of PAHs has been shown to be the principal process competing with radiative relaxation of these PAHs. Due to their high resilience towards decomposition PAHs are attractive compounds for photoionization studies.
Light from the Berlin synchrotron BESSY was used to investigate the fragmentation of various PAHs by means of standard ionisation and coincidence techniques. By evaporation of the solid substances in an oven an effusive beam of target molecules was produced. After having been ionized using photon energies between 10 eV and 30 eV the fragmentation of these PAHs has been analyzed by means of time of flight mass spectrometry.
At sufficiently high photon energies dissociation via splitting off H-atoms and CxHy-fragments is observed. The critical energies are determined and compared with appropriate values from electron bombardement ionisation. Experimentally taken breakdown curves are compared with RRKM calculations.