From the coincidence map shown in figure and from table II it can be seen that three different pairs of singly charged fragment ions are formed from the precursor dication [C 4 the hydrogen atoms distributed at the terminal carbons, [CH 2 CCCH 2 ] 2+ . In addition, we also obtained two close lying cyclic structures, one with 4-member carbon ring and another having a 3-member carbon ring. For C 4 H 2+ 3 dication, the lowest energy structure is once again a linear carbon chain with the hydrogen atoms distributed at the terminal carbons, [HCCCCH 2 ] 2+ and the next lowest energy structure has a cyclic 3-member carbon ring. Although we see both, cyclic and linear structures for these dications, our MD simulations shows higher distribution of linear ones. For both these dications, the formation of the highest energy structure is the most likely possibility for explaining appearance of fragment pairs (CH , is formed, several different processes become active for dissipation of excess energy of this dication. These processes include the emission of neutral particles (H/H 2 /C 2 H 2 ), hydrogen migration, and hydrogen scrambling, breaking of central or terminal C-C bonds, and breaking of C-H bonds. All these processes are sensitive to the internal energy of the dication and have different onset time scales. With ion-impact induced ionization, dications are expected to have a wide range of internal energy distribution. That this is the case, is evident from the large number of dissociation fragments observed in the experiment with involvement of all the different processes mentioned above.