  An important goal in molecular physics and chemistry today is to obtain
structure-dependent information about molecular function to obtain a deeper
understanding into chemical reactions. However, until now, asymmetric tops,
which comprise the widest and most general class of molecules, remain
principally unexplored. This gap is particularly evident in high harmonic
generation (HHG). HHG has successfully obtained structural information about
electron hole pairs or orbitals for simple linear molecules. Unfortunately, for
more complicated molecules, the emission from different molecular directions
interfere, concealing individual angular signatures. Here we introduce a method
to extract orientation-dependent information from asymmetric tops and apply it
to the sulfur dioxide (SO2) molecule. We use the rotational revival structure
to decompose the angular contributions of HHG emission. This method also
extends HHG-based tomographic imaging into three dimensions and makes it
applicable to a much wider class of systems than previously envisioned. Our
results suggest that HHG is a powerful tool to probe electron orbital structure
and dynamics of complex molecules.
