Dielectric properties of biological molecules in the Terahertz gap

In this work, results from parallel measurements of reflection and transmission spectra of biological molecules were utilized to enable detailed and direct calculation of the refractive index and absorption coefficient spectra in the Terahertz gap. The DNA samples from herring and salmon, as well as the protein Ovalbumin sample, have been characterized. The modeling technique is described. The reflection spectra have resonance features similar to those demonstrated earlier for transmission, thereby reaffirming molecular vibrational modes in biological materials. The dispersion of refractive index and absorption coefficient is demonstrated within the Terahertz gap of 10 cm(-1) to 25 cm(-1). The data yielded higher refractive index and absorption coefficient for the single stranded salmon DNA than for the double stranded counterpart, with several different vibrational modes.