  Femtosecond laser pulses are utilized to drive multiple ionization in
gas-phase formic acid dimers and ions are studied using time-of-flight mass
spectrometry. The interaction of formic acid dimer with 200 fs linearly
polarized laser pulses of 400 nm with intensi-ties up to 3.7x1015 W/cm2
produces a carbon monoxide trication. Experimental measurements of the kinetic
energy release of the ions are consistent with our molecular dynamics
simulations of the Coulomb explosion of a formic acid dimer and suggest that no
movement occurs during ionization. KER values were recorded as high as 44 eV
for CO3+. Potential energy curves for COn+, for n < 4, have been calculated
using CCSD(T) and confirm the existence of metastable states with a large
potential barrier with respect to dissociation. This combined experimental and
theoretical effort shows the existence of sufficiently long-lived CO3+.
