Rough surfaces quartz crystal

An electrochemical quartz crystal microbalance (EQCM or QCM) can be used to estimate the surface roughness of deposited lithium [43],... 

To mimic the PG electrode surface for QCM measurements of layers adsorbed on the gold-quartz resonators, we first chemisorb a mixed monolayer of mercaptopropionic acid/mercaptopropanol. This layer is represented by the first point in Fig. 2, labeled MPA. The second layer is PDDA. Quartz crystal microbalance frequency decreasing in a roughly linear fashion and at regular intervals for the multiple adsorption steps demonstrates repeatable adsorption for the two DNA/en-zyme films. Relative precision of layer formation on multiple resonators within 15% can be achieved. Film thicknesses and component weights in Table 1 were obtained by analyzing the QCM data with Eqs. 1 and 2. 

Daikhin, L. Urbakh, M., Influence of surface roughness on the quartz crystal microbalance response in a solution new configuration for qcm studies, Faraday Discuss. 1997,107, 27-38. 

Admittedly, some of the amazing simplicity of quartz crystal resonators is lost once the surfaces are covered with electrodes and the crystal is inserted into a holder. In this chapter, we mostly stick to an ideahstic view and describe the modeling as if there were none of these complications. We do not touch upon compressional waves [24,25], effects of varying temperature or stress [26,27], anharmonic side bands [23], roughness [28,29], bubbles and slip [30], or effects of a variable dielectric environment [31,32]. 

Quartz Crystals with Rough Surfaces Operating in Liquids. 130... 

Abstract In this chapter we discuss the results of theoretical and experimental studies of the structure and dynamics at solid-liquid interfaces employing the quartz crystal microbalance (QCM). Various models for the mechanical contact between the oscillating quartz crystal and the liquid are described, and theoretical predictions are compared with the experimental results. Special attention is paid to consideration of the influence of slippage and surface roughness on the QCM response at the solid-liquid interface. The main question, which we would like to answer in this chapter, is what information on... 

Fundamental frequency of the resonator Correlation function for surface roughness Root mean square height of a roughness Wave vector of shear waves in quartz, (Uy pq//rq Correlation length of surface roughness Thickness of the liquid film Thickness of interfacial layer Molecular dynamics Pressure in a liquid Quartz crystal microbalance Hydrodynamic roughness factor Electrochemical roughness factor Coordinates (normal and lateral)... 

An important part of modern experimental surface science and electrochemistry has been performed on single-crystal electrodes. In contrast, the metal deposited on the surface of the quartz resonator always has a rough surface and at best a preferred crystal orientation. Studies with a QCM having a true single crystal surface have not yet been reported. Making a thin (about 1 xm) stable single-crystal metal layer on the surface of quartz seems to be an insurmountable problem. 

In order for both mass and heat-flow sensors to operate, the thin-film sample must adhere to the top surface of the QCM and be of uniform thickness. The mechanical behaviour of films on the quartz microbalance has been modeled by Kanazawa(12), who examined the amplitude of the shear displacement in the quartz crystal and in the overlying film for several cases. For a 1 volt peak RF applied voltage typical of the Stanford Research Systems oscillator driver, the amplitude of the shear wave of a bare crystal is 132 nm. Mecca [29] has calculated the inertial acceleration at the centre of a similar quartz resonator, and finds that it is roughly 10 g, where g is the gravitational constant. At these extremely high accelerations, powder or polycrystalline samples do not follow the transverse motion of the QCM surface and cannot be used without being physically bound to the surface with a thin adhesive layer. 

Figure 4.17 Shift and change of the resonance frequency of a quartz crystal microbalance, real part of the admittance versus frequency, /q, Wq, resonance frequency and full width at half maximum (FWHM) of the initial gold electrode,/j, w, resonance frequency and FWHM of a gold electrode after formation of a rigid and smooth surface film (no damping), resonance frequency and FWHM of a gold electrode after formation of a viscoelestic and/or rough surface film (strong damping).

The Sauerbrey constant Cjb for a 10 MHz AT-quartz is 226.01 Hz cm pg (AT describes the type of cut, which is like a slice from a quartz crystal (Section 4.2.3)). It was mentioned that the application of the simple Sauerbrey equation is limited to rigid films. Polymer films can have viscoelastic properties or can develop a high surface roughness. In these cases the mechanical impedance contains terms that take into account viscoelasticity and surface roughness, and the resonance frequency shift becomes a complex quantity. 

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