We study experimentally the three-body Coulomb explosion dynamics of carbon dioxide dimer
\rm(CO_2)_2^4+
ions produced by intense femtosecond laser field. The three-dimensional momentum vectors as well as kinetic energy are measured for the correlated fragmental ions in a cold-target recoil-ion momentum spectrometer (COLTRIMS). Carbon dioxide dimer is produced during the supersonic expansion of
\rm(CO_2)_2
gas from a 30 μm nozzle with 10 bar backing pressure. The linearly polarized laser pulses with a pulse duration (full width at half maximum of the peak intensity) of 25 fs, a central wavelength of 790 nm, a repetition rate of 10 kHz, and peak laser intensities on the order of
\rm8 \times10^14\;\rmW/cm^2
are produced by a femtosecond Ti:sapphire multipass amplification system. We concentrate on the three-particle breakup channel
\rm(CO_2)_2^4+ \rightarrow \rmCO_2^2++\rmCO^++ \rmO^+
. The two-particle breakup channels,
\rm(CO_2)_2^4+ \rightarrow \rmCO_2^2++ \rmCO_2^2+
and
\rmCO_2^2+\rightarrow CO^++O^+
, are selected as well for reference. The fragmental ions are guided by a homogenous electric field of 60 V/cm toward microchannel plates position-sensitive detector. The time of flight (TOF) and position of the fragmental ions are recorded to reconstruct their three-dimensional momenta. By designing some constraints to filter the experimental data, we select the data from different dissociative channels. The results demonstrate that the three-body Coulomb explosion of
\rm(CO_2)_2^4+
ions break into
\rmCO_2^2++\rmCO^++\rmO^+
through two mechanisms: sequential fragmentation and non-sequential fragmentation, in which the sequential fragmentation channel is dominant. These three fragmental ions are produced almost instantaneously in a single dynamic process for the non-sequential fragmentation channel but stepwise for the sequential fragmentation. In the first step, the weak van der Waals bond breaks,
\rm(CO_2)_2^4+
dissociates into two
\rmCO_2^2+
ions; and then one of the C=O covalent bonds of
\rmCO_2^2+
breaks up, the
\rmCO_2^2+
ion breaks into
\rmCO^+
and
\rmO^+
. The time interval between the two steps is longer than the rotational period of the intermediate
\rmCO_2^2+
ions, which is demonstrated by the circle structure exhibited in the Newton diagram. We find that the sequential fragmentation channel plays a dominant role in the three-body Coulomb explosion of
\rm(CO_2)_2^4+
ions in comparison of the event ratio of the two fragmentation channels.