Statistical vs. direct dissociation of molecular dications.

Using a combination of theory and experiment, we study the dissociation of molecular dications. We compare trajectory surface hopping (TSH) and statistical (RRKM) calculations of the dissociation with covariance velocity map imaging of fragments from the dication after strong field double ionization. The measurements and calculations highlight the contrast between direct and statistical dissociation dynamics. By comparing the calculations with covariance velocity map imaging measurements, we are able to confirm key aspects of the calculations and validate the insights they provide. Detailed results for 1,4-cyclohexadiene dications are compared with measurements for ethylene and deuterated formaldehyde dications, highlighting differences in how energy is vibrationally redistributed before dissociation. In addition, we discuss measurements for the molecular dications 1,3-cyclohexadiene, 1,1,1-trifluoroacetone, and 1,4-cyclooctadiene.