Quartz crystal microbalance measures models

The author would like to thank Thomas Springer (Los Alamos) for many contributions to the mathematical modelling aspects mentioned here, Ruth Sherman (Los Alamos) who gathered much experimental data on RuOj, Judith Rishpon (University of Tel Aviv) who made the quartz crystal microbalance measurements of Fig. 14, and Bernard Boukamp (University of Twente) who has allowed the author to use his non-linear least-squared error fitting routines for impedance data analysis. 

The photoablation behaviour of a number of polymers has been described with the aid of the moving interface model. The kinetics of ablation is characterized by the rate constant k and a laser beam attenuation by the desorbing products is quantified by the screening coefficient 6. The polymer structure strongly influences the ablation parameters and some general trends are inferred. The deposition rates and yields of the ablation products can also be precisely measured with the quartz crystal microbalance. The yields usually depend on fluence, wavelength, polymer structure and background pressure. 

Slip is not always a purely dissipative process, and some energy can be stored at the solid-liquid interface. In the case that storage and dissipation at the interface are independent processes, a two-parameter slip model can be used. This can occur for a surface oscillating in the shear direction. Such a situation involves bulk-mode acoustic wave devices operating in liquid, which is where our interest in hydrodynamic couphng effects stems from. This type of sensor, an example of which is the transverse-shear mode acoustic wave device, the oft-quoted quartz crystal microbalance (QCM), measures changes in acoustic properties, such as resonant frequency and dissipation, in response to perturbations at the surface-liquid interface of the device. 

A similar catalytic effect of PbS on the decomposition of thiourea had been suggested previously by Norr [47]. Kinetic measurements by Rieke and Bentjen suggested that CdS likewise catalyzed thiourea decomposition [37], Ortega-Borges and Lincot also deduced such a mechanism based on kinetic measurements of the CdS deposition using a quartz crystal microbalance [48], In this case, the measurements were found to fit best with a complex-decomposition model. Both they and Rieke and Bentjen found optimum deposition to occur under conditions where Cd(OH)2 was formed as a surface species on the substrate but not in the bulk of the solution. Kinetic measurements also led Dona and Herrero to a similar conclusion of a complex-decomposition mechanism, but with the main difference that the initial adsorbed species is not Cd(OH)2 itself but an ammine-hydroxide [49] ... 

Most cascade impactors do not give data in real time. The collection surfaces must be removed from the device and subjected to chemical or gravimetric analysis. However, one impactor does give data in real time. The Model PC-2 Air Particle Analyzer (California Measurements, Inc., Sierra Madre, CA) achieves a real-time measurement by using piezoelectric quartz crystal microbalance (QCM) mass sensors to electronically weigh particles at each impactor stage [62,63], The device has 10 stages and separates the aerosol into... 

Schrebler et al. studied the nucleation and growth mechanisms for Re deposition on polyerystalline Au electrodes, from a bath containing 0.75 mM perrhenic acid and 0.1 M sodium sulfate at pH = 2. The potentiostatic step technique was simultaneously employed with measurements of mass changes in an electrochemical quartz-crystal microbalance. The mass vs. time transients were fitted with equations deduced from the current versus time relationships of the conventional nucleation and growth models. It was concluded that electrodeposition of Re started with progressive nucleation and two-dimensional growth, followed by two other contributions ... 

Mecca VM (2005) From quartz crystal microbalance to fundamental principles of mass measurements. Artal Lett 38 753-767 Bucur RV, Carlsson J-O, Mecea VM (1996) Quartz-crystal mass sensors with glued foil electrodes. Sens Actuators B 37 91-95 Bucur RV, Mecea VM, Carlsson J-O (2003) EQCM with air-gap excitation electrode. Calibration tests with copper and oxygen coatings. Electrochim Acta 48 3431-3438 Mecea V, Bucur RV (1979) The mechanism of the interaction of thin films with resonating quartz crystal substrates the energy transfer model. Thin Solid Films 60 73-84 Mecea V, Bucur RV, Indrea E (1989) On the possibility of thin film structure study with a quartz crystal microbalance. Thin Solid Films 171 367-375... 

D. Johannsmann, I. Reviakine, E. Rojas, and M. Gallego, Effect of sample heterogeneity on the interpretation of QCM(-D) data comparison of combined quartz crystal microbalance/atomic force microscopy measurements with finite element method modeling. Anal. Chem., 80, 8891-8899 (2008). 

The reaction scheme of Bode [11] was derived by comparison of the X-ray diffraction patterns of the active materials with those for the model compounds. How the 8-Ni(OH)2 in battery electrodes differs from the model compound is discussed in Section 5.3.I.3. In recent years, the arsenal of in situ techniques for electrode characterization has greatly increased. Most of the results confirm Bode s reaction scheme and essentially all the features of the proposed a/y cycle. For instance, recent atomic force microscopy (AFM) of o -Ni(OH)2 shows results consistent with a contraction of the interlayer distance fiom 8.05 to 7.2 A on charge [61-63]. These are the respective interlayer dimensions for the model a-Ni(OH)2 and y-NiOOH compounds. Electrochemical quartz crystal microbalance (ECQM) measurements also confirm the ingress of alkali metal cations into the lattice upon the conversion of a-Ni(OH)2 to y-NiOOH [45,64,65]. However, in situ Raman and surface-enhanced Raman spectroscopy (SERS) results on electrostretching modes that are consistent with a weakening of the O-H bond when compared with results for the model a- and 8-Ni(OH)2 compounds [66]. This has been ascribed to the delocalization of protons by intercalated water and Na ions. Similar effects have been seen in passive films on nickel in borate buffer electrolytes [67]. 

Lead Pronounced effects of Pb (Fig. 3) were interpreted in terms of a third-body effect by Adzic and coworkers [35]. Pb adatoms suppress adsorption of hydrogen and strongly bound intermediates, in particular, those interacting with two or three surface sites. The same model was assumed for Bi and Tl. Adsorbed H was considered to take part in the formation of strongly bound intermediates [18,19]. Current responses to potential sweeps into the H adsorption region [18,19, 65] and crystal quartz microbalance measurements [66]... 

It is important to note that determination of the width of the resonance can be critical for the use of the EQCM as a true microbalance. Relating A/ to the change in mass Am employing Eq. (17.1) is only valid if the parameter T is constant in a given composition of the solution and at constant temperature and pressure. In the general case, it may be better to regard the QCM as a quartz crystal microsensor. On the other hand, measurement of both A/ and F can be very useful in more advance analysis of the structure of the metal/electrolyte interface, employing suitable models, which can be tested experimentally. 

---