Photodetachment study of He − quartet resonances below the He ( n = 3 ) thresholds

9 A pr 1 99 8 Photodetachment study of He − quartet resonances below the He ( n = 3 ) thresholds

The photodetachment cross section of He has been measured in the photon energy range 2.9 . . . 3.3 eV in order to investigate doubly excited states. Measurements were made channel specific by selectively detecting the residual He atoms left in a particular excited state following detachment. Three Feshbach resonances were found in the He(1s2p P)+e(ǫp) partial cross section: a S resonance below ...

Photodetachment of He- in the vicinity of the He* (n=3, 4, and 5) thresholds

Parallels between high doubly excited state spectra in Hâ•fi and Liâ•fi photodetachment

Eigenchannel R-matrix calculations for photodetachment of H– up to the H(n = 6) threshold provide complete theoretical confirmation of observed high-lying, doubly excited state spectra. Long-range multipole interactions beyond the reaction volume are found to play an important role. Similar calculations for Li– photodetachment up to the Li(n = 6) threshold predict analogous resonance structures...

On doubly excited states in negative ions

Atomic negative ions are fragile quantum systems with a binding energy one order of magnitude smaller than for atoms. Due to this weak binding, correlation among the valence electrons plays a very important role. For doubly excited states, where two electrons are simultaneously promoted, correlation becomes dominant and is thus no longer a small perturbation to the independent particle behaviou...

Interaction between overlapping doubly excited resonance series for the He atom

We present a detailed theoretical study on the photoionization from the bound excited 1P state of He to continua dominated by multiple doubly excited resonance series embedded in multiple single-ionization channels between the N = 2 and N = 3 thresholds. In addition to identifying the individual resonance series, our investigation has also demonstrated unambiguously the level crossing between o...