Electron impact ionization of thymine clusters embedded in superfluid helium droplets
- 106 Downloads
Embedding molecules in helium clusters has become a powerful technique for the preparation of cold targets for spectroscopy experiments, as well as for the assembly of complex, fragile molecular species. We have recently developed a helium cluster source and a pick-up cell to produce neutral beams of doped helium droplets, to be used as targets in studies on electron collisions with molecules of biological relevance. In the present work we present the results of a series of experiments on electron-impact ionization of helium clusters doped with thymine and 1-methylthymine, where several interesting phenomena were observed, i.e., (i) electron impact ionization of molecular clusters inside the helium droplets leads predominantly to protonated clusters; (ii) the appearance energies are close to the ionization threshold of the helium atom but ionization efficiency curves in addition extend down by several eV; (iii) ionized molecular clusters can undergo metastable decay via the loss of one neutral monomer.
PACS.34.80.Gs Molecular excitation and ionization by electron impact 36.40.Qv Stability and fragmentation of clusters 82.33.Fg Reactions in clusters 87.50.Gi Ionizing radiations
Unable to display preview. Download preview PDF.
- C. Plützer, I. Hünig, K. Kleinermanns, E. Nir, M.S. de Vries, Chem. Phys. Chem. 4, 838 (2003) Google Scholar