Characteristics of immersion angle dependence of the resonant frequency shift of the quartz crystal microbalance in solutions

We investigated the immersion angle dependence of the resonant frequency shift (ΔF) of the quartz crystal microbalance (QCM) in a Newtonian liquid from the point of view of the QCM oscillation direction. In this paper, the three cases of immersion angles were employed. In Case I, the angles of both the surface with the electrode (x-z surface) and the QCM oscillation direction varied at the same time. In Case II, the QCM oscillation direction changed while the x-z surface of the QCM was kept parallel to the gravity direction. In Case III, the angle of the x-z surface of the QCM changed, while the QCM oscillation direction was constantly kept perpendicular to the gravity direction. This study elucidated that the ΔF values changed with the immersion angles in Cases I and III, and unchanged in Case II. As a result, we have found that only when the x-z surface of the QCM is not parallel to the gravity direction, the immersion angle dependence of ΔF appears. Namely, it has become clear that the immersion angle dependence of ΔF has no relation to the QCM oscillation direction.