One of the surprising consequences of equation 3 is that some achiral chromophores exhibiting local mirror-plane symmetry in may produce nonzero chiral elements, as outlined by the Simpson group. This serves as a theoretical basis for chiral SFG methods probing hydration structures of biomolecules because it implies that achiral water molecules arranged in chiral superstructures at interfaces can produce chiral SFG signals. Thus, chiral SFG can selectively probe the biomolecular hydration shell without interference from bulk water. By manipulating the polarization of the IR and visible beams and the polarization setting for detecting SFG signals, particular components of can be isolated. For example, the psp polarization measures the response from the elements , , , and , where p is polarization on the incident plane and s is polarization perpendicular to the incident plane, and the order of the subscript notation of psp is for the SFG, visible, and IR beams, respectively. Of the four elements, only survives in a uniaxial system with C¥ symmetry and in the absence of electronic resonance. Hence, we measure in our chiral SFG experiments under the conditions of electronic nonresonance and compute to simulate chiral SFG spectra.