On the spatial alignment of bent triatomic molecules by intense, picosecond laser fields

Angular distributions have been measured of the products of dissociative ionization (DI) of the bent triatomic molecules H<SUB>2</SUB>O,N O<SUB>2</SUB> and S O<SUB>2</SUB> induced by intense (10<SUP>L3</SUP> Wcm<SUP>-2</SUP>), linearly polarized electric fields generated using 35 ps long laser pulses at a wavelength of 532 nm. Both the O<SUP>+</SUP> and O H<SUP>+</SUP> fragments produced upon DI of H<SUB>2</SUB>O possess isotropic angular distributions. O<SUP>+</SUP> and N O<SUP>+</SUP> fragments from DI of N O<SUB>2</SUB> are formed with very marked anisotropies, whereas the O<SUB>+</SUB> fragment resulting from DI of S O<SUB>2</SUB> exhibits a weak anisotropy. Attempts are made to rationalize these angular distributions in terms of anisotropy of the induced dipole moments of the ground-state precursors and the resulting interaction potentials, in each case. Good accord is reached between the measured data and the results of an approximate, but ab initio, theoretical treatment which indicates that the relative magnitudes of the components of the induced dipole moment, which lie parallel and perpendicular to the molecular symmetry axis, appear to influence the angular distributions