Aachen PK 2003 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe
P: Plasmaphysik
P 4: Poster I
P 4.8: Poster
Montag, 17. März 2003, 17:45–19:15, Foyer
Do hydrogenic Rydberg molecules contribute to the H−-formation in low temperature plasmas ? — •Thomas Mosbach and H.F. Döbele — Institut für experimentelle Physik, Universität Essen, D-45117 Essen
The population of the electronic and rovibronic states of molecular hydrogen have found particular interest in connection with negative hydrogen ion densities in low temperature hydrogen plasmas. Dissociative attachment of low-energy electrons to electronic ground state molecules in high rovibronic levels and to highly electronically excited molecules – Rydberg molecules – are considered as important formation channels. We consider the contribution of the formation channel via Rydberg molecules to the total density of negative ions in a magnetic multipole plasma source. We apply detailed rate coefficients for relevant gas temperatures and electron energy distribution functions to determine the stationary population of molecular Rydberg states. State-selective rate coefficients for dissociative electron attachment are used in order to determine the H−-formation rate on basis of the stationary populations found. These rates are compared with corresponding rates of dissociative attachment to highly excited H2 molecules in the electronic ground state. We come to the conclusion that the Rydberg channel can be neglected as an efficient source of negative ions in low temperature plasmas.
This work was supported by the DFG in the frame of the SFB 191.