https://doi.org/10.1140/epjd/e2007-00275-5
Lifetime of the Cs 6P1/2 state in bcc and hcp solid 4He
1
Département de Physique, Université de Fribourg (), Chemin du Musée 3, 1700 Fribourg, Switzerland
2
EPFL, Lausanne, Switzerland
Corresponding author: a adrian.hofer@unifr.ch
Received:
16
May
2007
Revised:
4
September
2007
Published online:
26
September
2007
We present the first experimental study of time-resolved fluorescence from laser-excited Cs(6P1/2) atoms isolated in a solid 4He matrix. The results are compared to the predictions of the bubble model including the interaction of the atomic dipole with its radiation reflected at the bubble interface. Our results show that in liquid He as well as in the body-centered cubic (bcc) crystalline phase of He the lifetime of excited Cs atoms does not depend on He pressure, in agreement with our theory. When going from the bcc to the hexagonally close-packed (hcp) phase of 4He the lifetime is reduced by ≈10% and decreases further with increasing He pressure. We assign this effect to the formation of Cs*Hen exciplexes, and determine the pressure dependence of the probability that the 6P1/2 state decays via this nonradiative channel.
PACS: 32.70.Cs – Oscillator strengths, lifetimes, transition moments / 67.40.Yv – Impurities and other defects / 82.20.Xr – Quantum effects in rate constants (tunneling, resonances, etc.)
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2007