K. Fritioff

Relative cross sections for the electron impact single detachment on Li

The electron impact single detachment process on Li− targets was studied using the storage ring CRYRING located at the Manne Siegbahn Laboratory in Stockholm, Sweden. The Li− ions, first stored in the storage ring, were merged with a cold, 1.4 cm in diameter, electron beam. The neutral Li atoms, originating from the process under scrutiny, were recorded by an energy-sensitive surface barrier detector in order to measure the relative electron single detachment cross section. The findings are the following. The cross section increases smoothly above the 1.4 eV detachment threshold and reaches a maximum at about 12 eV. At even larger energies a slow decrease, which follows the ln (E)/E energy dependence predicted by the Bethe–Born approximation, is observed.

Observation of an excited C2−4 ion

This paper reports an experimental investigation of the electron impact detachment of C−4. We observe structure in the electron impact cross section for detaching a single electron from a C−4 cluster anion, which we attribute to the formation and decay of the C2−4 dianion. The system is energetically unstable and very rapidly decays via double autodetachment. The energy and width of the resonance were determined to be 8.8(5) eV and 1.4(5) eV, respectively, and the resonance lies 1.5(5) eV above the ground state of the neutral system. The experiment was conducted by merging monoenergetic electron and ion beams in the heavy ion storage ring CRYRING. The detachment channel was monitored by detecting neutral C4 fragments.