DISSOCIATION REACTIONS OF (CO2)n+ (2≦n≦9) CLUSTER  IONS IN  
                                  COLLISION WITH He ATOM

                H. Sakai$^\ast$ , A. Fujino$^\ast$ ,T. Koizumi$^\ast$ and Y. Itoh$^\sharp$

    $^\ast$Department of Physics, Rikkyo University,Nishi-Ikebukuro 3, Toshima-ku, Tokyo 171-8501,Japan
    $^\sharp$Physics Laboratory, Josai University,Sakado, Saitama 350-0295,Japan
    
The dissociation cross sections of (CO2)n+ cluster ions in collision with He atoms have been measured in 
the laboratory energy region from 300 to 800 eV . The monomer-ion production cross section increases 
rapidly with the increase of the ion velocity, and reaches the maximum value about 1x10-16 cm2 at 3x106
　cm/s.  The monomer-loss cross sections are more than an order of magnitude larger than the monomer-ion 
production cross sections and decrease monotonically with the increase of the ion velocity.