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Population and deactivation of lowest lying barium levels by collisions with He, Ar, Xe and Ba ground state atoms

  • C. Vadla
  • K. Niemax
  • V. Horvatic
  • R. Beuc
Article

Abstract

Excitation transfer between the barium low lying excited states 6s6p3P 1 0 , 6s5d1D2 and 6s5d3DJ by collisions with He,Ar,Xe and Ba has been investigated. The population densities in all levels involved were probed by absorption or by fluorescence usingcw lasers. The depopulation cross sections of the Ba3P 1 0 state by collisions with noble gases were found to be σHe(3P 1 0 )=5.5·10−16 cm2, σAr(3P 1 0 )=4.6·10−16 cm2, and σXe(3P 1 0 )=1.7·10−16 cm2. For Ar, the collisional depopulation of the3P 1 0 level is exclusively due to the transition to the1D2 state. Under the assumption that the3DJ metastable states are populated collisionally by1D23DJ transfer only, we have deduced the upper limit for the corresponding cross section σ 13 Ar =1.5·10−18 cm2. From the Ba1D2 and Ba3DJ steady-state diffusion distributions, collisional relaxation rates of the1D2 and3DJ levels were evaluated. The collisional relaxation rates by Ar and Ba yielded total cross sections for the depopulation of metastable levels: σAr(1D2)=1.5·10−17 cm2, σBa(1D2)℞1·10−13 cm2, σAr(3DJ)=7·10−21 cm2, and σBa(3DJ)=1·10−15 cm2. Furthermore, it was found that the main contribution of the collisional depopulation of the1D2 state by Ar is related to back transfer to the3P J 0 state, whereas the deactivation of the3DJ metastable state is due to back transfer to the1D2 state. Taking into account other cross sections reported in literature we can conclude that collisional deactivation of both metastable levels by Ba ground state atoms can be attributed to their mutual collisional mixing.

PACS

34.50 32.00 

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Copyright information

© Springer-Verlag 1995

Authors and Affiliations

  • C. Vadla
    • 1
  • K. Niemax
    • 2
  • V. Horvatic
    • 1
  • R. Beuc
    • 1
  1. 1.Institute of Physics of the UniversityZagrebCroatia
  2. 2.Institut für PhysikUniversität HohenheimStuttgartGermany

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