Employing polyethylene as contacting agent between ATR-crystals and solid samples with hard surfaces

Using a single crystal of fresnoite (Ba2TiSiO8), we demonstrate that polyethylene (PE) can be used as a contacting agent to enable the recording of ATR-spectra of materials with hard surfaces. The performance of our method is compared with the standard according to literature where CS2 is used as an immersion liquid. A Harrick Seagull cell, equipped with a ZnSe semi-sphere ATR-crystal has been used in measuring s- and p-polarized spectra at different incidence angles. The experimental results were compared with model calculations based on the dielectric function tensor of fresnoite. The comparison reveals advantages of our method compared to the use of CS2 like: closer resemblance between experimental and modeled spectra, repeatability and persistent optical contact. Moreover, our technique is easier to use.