ABSOLUTE PHOTOIONIZATION CROSS SECTION MEASUREMENTS OF Xe^+ IONS IN THE
4d-THRESHOLD ENERGY REGION


A. Ito*, Y. Itoh&, M. Kitajima#, T. Koizumi*, T. M. Kojima$, H. Sakai*, M.
Sano# and N. Watanabe+


* Department of Physics, Rikkyo University, Tokyo 171-8501, Japan
& Physics Laboratory, Josai University, Saitama 350-0295, Japan
# Department of Physics, Sophia University, Tokyo 102-8554, Japan
$ The Institute of Physical and Chemical Research, Saitama 351-0198, Japan
# Photon Factory, KEK, Ibaraki 305-0801, Japan
+ Institute of Low Temperature Science, Hokkaido University, Hokkaido
060-0819, Japan


By using a photon-ion merged-beam apparatus, absolute photoionization cross
sections for Xe^2+ and Xe^3+ 
production from the Xe^+ ions (4d^10 5s^2 5p^5  ^2P_3/2,1/2) were measured
in the energy range from 80 eV to 
140 eV. The energy dependence of the cross section for Xe^3+ production
shows typical 4d "giant" resonance 
structure and the cross section has maximum value of 2.7 x 10^-17 cm^2 at
about 100 eV. The cross section for
Xe^2+ production does not show strong energy dependence; the maximum value
is 3.4 x 10^-18 cm^2 at about 100 eV.