Dresden 2006 – scientific programme

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CPP: Chemische Physik und Polymerphysik

CPP 13: POSTER New Experimental Techniques

CPP 13.10: Poster

Tuesday, March 28, 2006, 17:00–19:00, P3

Torsional Quartz Crystal Resonators Contacting the Sample Face-On:Technical Aspects and Application to the Film Formation Process — •Alexander Martin König, Binyang Du, and Diethelm Johannsmann — Institute of Physical Chemistry, Clausthal University of Technology,Arnold-Sommerfeld-Str. 4, 38678 Clausthal-Zellerfeld

Traditional AT-cut quartz crystal resonators operating in MHz range are extensively used to explore the interfacial properties of coatings. However, the penetration depth of the shear wave emanating from AT-cut resonators typically is hundreds of nanometers, limiting their applicability to thicker coatings. X-cut torsional resonator-operating in kHz range-provide for a complementary approach. Here, the penetration depth is hundreds of micrometers. We report on the use of torsional resonators only contacting the sample across the front face of the cylinder. As we show, the equations for the analysis of AT-cut resonator measurements can be used in the same way for torsional resonators operated in this mode. In particular, the experimental results show that the Sauerbrey equation also holds for torsional resonators. This finding turns them into suitable devices for investigating the film-formation process. By varying the concentration of the colloidal dispersions and controlling the evaporation rate of the solvent, different mechanisms of film-formation were observed. The mechanism of film formation can be inferred from the evolution of frequency and bandwidth as a function of time. The film is formed via wet-sintering for slow evaporation, while for fast evaporation the film is formed via dry-sintering.