DYNAMICAL ASPECTS OF PHOTOELECTRON ANGULAR DISTRIBUTIONS
FROM K-SHELLS OF ORIENTED CO2 

K. Ito*, J. Adachi#, Y. Hikosaka*, S. Motoki*,$, M.Sano*, K. Soejima%, A.
Yagishita*, 
Kwanghsi Wang& and V. McKoy& 

*Photon Factory, Institute of Materials Structure Science, KEK, Tsukuba
305-0801, Japan
#Institute of Molecular Science, Okazaki 444-0864, Japan
$Graduate School of Science and Technology, Chiba University, Chiba
263-0022, Japan
%Graduate School of Science and Technology, Niigata University, Niigata
950-2102, Japan
&A. A. Noyes Laboratory of Chemical Physics, California Institute of
Technology, Pasadena, CA 91125, U. S. A.

The angular distributions of O-1s photoelectrons from oriented CO2
molecules have been measured by detecting the photoelectrons in coincidence
with the fragment ions. It is found that the angular distributions in
parallel transition show dramatic changes across the sg and su shape
resonances. Ab-initio calculations suggest that the present experimental
results are ascribed to the symmetry breaking due to the anti-symmetric
motion of the oxygen atom in the O-1s photoionization processes.