Time-Domain Measurement of the Complex Chiro-Optical Susceptibility by an Ultra-Stable Common-Path Interferometer

Chirality is the sense of twist that many natural systems exhibit: an object is chiral if it differs from its mirror image, i.e. if it cannot be superimposed onto it, like our left and right hands. Chirality of molecules plays a vital role in chemistry and biology, as it has a strong influence on their biochemical functions. Its characterization is therefore required for many applications in the chemical, pharmaceutic, and food industries. Interaction of chiral molecules with light gives rise to circular dichroism (CD) and circular birefringence (CB), i.e., difference in absorbance and refraction, respectively, between left and right circularly polarized light. Here we present an innovative device for measuring CD and CB spectra over a broad wavelength range from the IR (to access vibrational fingerprints) to the UV spectral region (e.g. to study protein structures), combining time-domain detection with self-heterodyne amplification.