Exploring trends in strong-field dissociation of small polyatomic molecules*

Using a 3-D coincidence momentum imaging technique, we examine trends in intense ultrafast laser-induced two-body dissociation and dissociative ionization of an N$_2$O$^+$ ion beam. As an example, it is observed that in both dissociation and dissociative ionization, the N-N bond is more likely to break than the N-O bond for typical laser pulses (Fourier transform-limited, 800 nm, $\sim$30 fs, $\sim$10$^{15}$ W/cm$^2$). This finding is perhaps counterintuitive in light of the stronger bond between the two N atoms in the ground state of N$_2$O$^+$. Utilizing our measured kinetic energy release and angular distribution spectra and the molecule's published electronic structure, we explain this and other trends in bond cleavage and charge localization preference. We also draw comparisons to other triatomic molecular ions, such as CO$_2$$^+$, and attempt to gain insight into the relative importance of chemical bond strength and the spacing of the relevant potential energy surfaces.