Polarization terahertz spectroscopy application to theophylline anhydrite single crystal for vibrational mode assignment

Theophylline anhydrite single crystal thin enough for wide range THz transmittance spectroscopy could be grown by Temperature Difference Method in aqueous solution. Polarization dependent THz transmittance spectra of the crystal at 70 K were obtained by using a GaP CW THz spectrometer. Absorption lines existing at close frequency could be resolved each other successfully. Assignments of absorption peaks were performed by comparing with the results of measurement and DFT calculation in periodic boundary condition.