Analysis of THz Scattering of Compacted Granular Materials using THz-TDS

Scattering of terahertz radiation in compacts is of great interest due to its potential to non-destructively assess various structural elements such as particle size and defects in compacts. In this study, we isolate the scattering contributions to the loss coefficient of borosilicate glass microspheres suspended in a polytetrafluoroethylene (PTFE) compact measured by terahertz time-domain spectroscopy. The particle size and concentration of microspheres in the compacts were varied to resolve their effect on terahertz scattering.

I. Introduction

Terahertz time-domain spectroscopy (THz-TDS) is a nondestructive and non-ionising technique currently being employed in various industries for process monitoring [1]. Current applications in the pharmaceutical industry are tablet coating analysis, identification of polymorphic forms and determination of porosity in solid oral dosage forms [1], [2], [3]. One promising and underdeveloped application of THz-TDS is the estimation of the size of structural components, e.g., particle size changes in pharmaceutical tablets due to agglomeration or fragmentation that impacts product performance.