With Terahertz Circular Dichroism Spectroscopy: Calibration using Magnetic Circular Dichroism

Chirality is an essential and universal feature of life. All living organisms are composed of macromolecules that are net chiral. These macromolecules are believed to have strong and broad absorptions in the terahertz frequency range and, due to their net chirality, will exhibit terahertz circular dichroism (TCD). Net chirality is a feature that exists exclusively in biological matter. Non-biological matter exists in equal abundance of both chiral form, and will not respond to terahertz radiation with the production of TCD. Because of this we propose the use of TCD spectroscopy for the unambiguous detection and identification of biological materials, without any prior assumption of chemical composition and reaction processes necessary for life, and irrespective of the non-biological backgrounds in the sample. This is additionally appealing because every unique biopolymer will construct a correspondingly unique TCD signal or 'fingerprint' from which a catalog can be compiled. We have designed and engineered a TCD spectrometer. This summer we aim to develop and produce a calibration device for our TCD spectrometer. To accomplish this we have designed and created a modified Helmholtz coil. We use current-carrying coils to generate tunable magnetic circular dichroism signals within a thin slab of the semi-conductor Indium Antimonite.