Response of a quartz crystal microbalance to a localized heat source: The case of MeV ion irradiation

Abstract

Quartz crystal microbalances (QCMs) are capable of detecting mass changes down to 10 pg cm⁻² s⁻¹, but thermal and stress effects must be accounted for, even when SC-cut (stress-compensated) crystals are used. In this study, we examine the compatibility of two measurement techniques: A high-sensitivity QCM and ion beam analysis (IBA). When used hand in hand, IBA can complement the information obtained from a QCM by providing element-specific data. Our results show that the QCM operation is strongly influenced by the power dissipation of the ion beam. Since QCM operation requires thermal equilibrium, IBA should be performed after the QCM measurements. Large frequency changes occur during irradiation and the thermal relaxation after irradiation. We model these effects, which are due to both the direct temperature effect on the frequency and the influence of thermal stress. The frequency response has a fast and a slow component. The fast frequency change (within ≈1 s) is related to the inhomogeneous temperature distribution in the quartz plate, while the slow component is due to the low thermal conductivity between the quartz crystal and the holder. Further effects such as the influence of the beam damage on the crystal frequency are discussed.