Evidence of capillary action in multilayered fibrous media observed with THz spectroscopy

Paper in proceeding, 2023

Here we investigate the applicability of the stratified media model to complex, multilayered media. THz reflectivity spectra of drying cellulose-based material show pronounced, frequency dependent reflectivity reduction below dry reflectivity. Analysis suggests the remaining water is distributed at the top surface of the paper thus consistent with a capillary in opposition to gravity.