Observation of Spurious Spectral Features in Mixed-Powder Compressed Pellets Measured by Terahertz Time-Domain Spectroscopy

Spurious loss features were observed in mixed-powder compressed pellets measured in transmission using terahertz time-domain spectroscopy. Loss features were identified in two types of pellets: polytetrafluoroethylene (PTFE)-glass microspheres and PTFE-lactose. The features were found to be dependent on grain size and concentration. An explanation is proposed, based on varying optical thickness of the sample material.