Biological Sensing via THz Circular Dichroism

Terahertz (THz) circular dichroism spectroscopy may provide a means for detecting life in various materials and characterizing biopolymers. Theoretical and experimental evidence have suggested that the spectral features of biopolymers are unique in the THz region since all major classes of biopolymers absorb electromagnetic radiation strongly in that area. Circular dichroism (CD) is the differential absorption of left and right circularly polarized light. Due to the sensitivity of THz CD to molecular asymmetry, biological materials, which are chiral, will produce net THz CD spectra. Since abiological materials are achiral, their THz absorptions will not produce net CD nor encumber THz CD spectroscopy signals arising from biological materials. Therefore, THz CD spectroscopy should allow spectral identification that is unique for biological materials even in the presence of abiological materials. The goal of this research is to assess THz CD spectroscopy as a possible method for life detection and biopolymer classification. A THz CD spectrometer utilizing intense and broadly tunable THz radiation from the UCSB free electron laser is being built to perform the necessary measurements.