München 2004 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe
MS: Massenspektrometrie
MS VIII: HV VIII
MS VIII.1: Hauptvortrag
Donnerstag, 25. März 2004, 12:30–13:00, HS 112
Free-electron-laser based IR spectroscopy of gas-phase cluster ions — •Gert von Helden1, Andre Fielicke2, and Gerard Meijer1,2 — 1Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin — 2FOM Institute for Plasmaphysics, Edisonbaan 14, NL-3439 MN Nieuwegein
For the characterization of gas-phase cluster ions, it is desirable to obtain more information than just the knowledge of the mass to charge ratio. In principle, spectroscopic data can give unique insight into the structure and properties of such species. In the infrared (IR) spectral region, the vibrational modes of the clusters are probed and direct information on the forces that hold the cluster together is obtained. However, experimental methods are limited by the availability of bright and tunable IR light sources. We use pulsed radiation from the free-electron laser FELIX to measure vibrational spectra of size selected gas-phase neutral or ionic species. FELIX has a tuning range from 40 to 2000 wavenumbers. The light comes in 5 microsecond long macropulses with energies of up to 150 mJ. This makes FELIX an ideal tool to resonantly pump large amounts of energy into gas-phase species. This absorbed energy can then induce secondary processes such as fragmentation or ionization. Measuring their yield as a function of excitation wavelength can give an IR spectrum of the (neutral or charged) molecule or cluster. In the presentation, IR spectra of various mass-selected metal cluster ions will be presented and discussed.