Faculté des sciences

Discovery of dumbbell-shaped CsHe(n) exciplexes in solid ⁴He

Nettels, Daniel ; Hofer, Adrian ; Moroshkin, Peter ; Müller-Siebert, Reinhard ; Ulzega, Simone ; Weis, Antoine

In: Physical Review Letters, 2005, vol. 94, p. 063001

We have observed several new spectral features in the fluorescence of cesium atoms implanted in the hcp phase of solid helium following laser excitation to the 6²P states. Based on calculations of the emission spectra using semi empirical Cs-He pair potentials the newly discovered lines can be assigned to the decay of specific Cs*He(n) exciplexes: an apple-shaped Cs(AП(3/2))He₂ and a... Plus

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    Summary
    We have observed several new spectral features in the fluorescence of cesium atoms implanted in the hcp phase of solid helium following laser excitation to the 6²P states. Based on calculations of the emission spectra using semi empirical Cs-He pair potentials the newly discovered lines can be assigned to the decay of specific Cs*He(n) exciplexes: an apple-shaped Cs(AП(3/2))He₂ and a dumbbell-shaped Cs(AП(1/2))He(n) exciplex with a well-defined number n of bound helium atoms. While the former has been observed in other environments, it was commonly believed that exciplexes with n>2might not exist. The calculations suggest Cs(AП(1/2))He₇ to be the most probable candidate for that exciplex, in which the helium atoms are arranged on a ring around the waist of the dumbbell-shaped electronic density distribution of the cesium atom.