We have observed, for the first time, LS-forbidden triplet doubly excited states, in single photon excitation of ground state helium, below the second ionization threshold. These states are identified as 3Do and 3Po and their excitation is due to spin-orbit interaction that mixes them with the optically allowed 1Po states. This observation is possible due to the very high efficiency in detecting metastable atoms created after the fluorescence decay of the doubly excited states, and the new capabilities of third generation synchrotron vacuum ultraviolet sources with high resolution beam lines.
Observation of triplet doubly excited states in single photon excitation from ground state helium / F., Penent; P., Lablanquie; R. I., Hall; M., Zitnik; K., Bukar; Stranges, Stefano; R., Richter; M., Alagia; P., Hammond; J. G., Lambourne. - In: PHYSICAL REVIEW LETTERS. - ISSN 0031-9007. - STAMPA. - 86:13(2001), pp. 2758-2761. [10.1103/physrevlett.86.2758]
Observation of triplet doubly excited states in single photon excitation from ground state helium
STRANGES, Stefano;
2001
Abstract
We have observed, for the first time, LS-forbidden triplet doubly excited states, in single photon excitation of ground state helium, below the second ionization threshold. These states are identified as 3Do and 3Po and their excitation is due to spin-orbit interaction that mixes them with the optically allowed 1Po states. This observation is possible due to the very high efficiency in detecting metastable atoms created after the fluorescence decay of the doubly excited states, and the new capabilities of third generation synchrotron vacuum ultraviolet sources with high resolution beam lines.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.