Damping Mechanisms of Piezoelectric Quartz Tuning Forks Employed in Photoacoustic Spectroscopy for Trace Gas Sensing

A study of the dependence of main loss mechanisms on the geometry of piezoelectric quartz tuning forks (QTFs) is reported. The influence of these loss mechanisms on the quality factor Q occurring while the QTF vibrates at the in-plane flexural fundamental and first overtone resonance modes is investigated. From this study, two QTFs efficiently operating both at the fundamental and first overtone mode are designed and realized. Data analysis demonstrates that air viscous damping is the dominant energy dissipation mechanism for both flexural modes. However, at the first overtone mode the air damping is reduced and higher quality factors can be obtained when operating at the first overtone mode with respect to the fundamental one.