Abstract We report the observation of superfluourescence at wavelengths (in air) of 501.6 nm, 667.8 nm, and 728.1 nm following the excitation of helium atoms with free-electron laser pulses at wavelengths of 53.7 nm (n = 3 excitation) and 52.2 nm (n = 4 excitation). The observed wavelengths of the superfluorescence pulses correspond to 1s3p-1s2s, 1s3d-1s2p, and 1s3s-1s2p transitions. Observation of superfluorescence on these transitions implies either competing cascade decays, or direct excitation of non-dipole allowed transitions. We have studied the time structure of the emitted pulses using a streak camera, and the results cannot be explained by straightforward considerations using the usual model for two-level superfluorescence.
|Journal||Journal of Physics B: Atomic, Molecular and Optical Physics|
|Publication status||Published - May 28 2015|
ASJC Scopus subject areas
- Condensed Matter Physics
- Atomic and Molecular Physics, and Optics