  We studied the effect of nuclear-quadrupole interactions on the field-free
impulsive alignment of different asymmetric-top molecules. Our analysis is
focused on the influence of the hyperfine- and rotational-energy-level
structures. These depend on the number of nuclear spins, the rotational
constants, and the symmetry of the tensors involved in the nuclear spin and
external field interactions. Comparing the prototypical large-nuclear-spin
molecules iodobenzene, 1,2-diiodobenzene, 1,3-diiodobenzene, and
2,5-diiodobenzonitrile, we demonstrate that the magnitude of the hyperfine
splittings compared to the rotational-energy splittings plays a crucial role in
the spin-rotational dynamics after the laser pulse. Moreover, we point out that
the impact of the quadrupole coupling on the rotational dynamics decreases when
highly excited rotational states dominate the dynamics.
