Quartz-crystal microbalance probe

We first experimented with the Quartz Crystal Microbalance (QCM) in order to measure the ablation rate in 1987 (12). The only technique used before was the stylus profilometer which revealed enough accuracy for etch rate of the order of 0.1 pm, but was unable to probe the region of the ablation threshold where the etch rate is expressed in a few A/pulse. Polymer surfaces are easily damaged by the probe tip and the meaning of these measurements are often questionable. Scanning electron microscopy (21) and more recently interferometry (22) were also used. The principle of the QCM was demonstrated in 1957 by Sauerbrey (22) and the technique was developed in thin film chemistiy. analytical and physical chemistry (24). The equipment used in this work is described in previous publications (25). When connected to an appropriate oscillating circuit, the basic vibration frequency (FQ) of the crystal is 5 MHz. When a film covers one of the electrodes, a negative shift <5F, proportional to its mass, is induced ... 

The process of Pb deposition depends on the presence of adsorbed species. On polycrystalline gold, in HCIO4 acid solutions, a combined quartz crystal microbalance and probe beam deflection methods have pointed to three stages of the process - (1) water molecules release from gold surface, (2) metal UPD associated with adsorbed OH ions replacement, followed by (3) water formation [274]. In the presence of adsorbed anions or organic... 

Pb UPD on polycrystalline An electrode in 0.1 M perchloric acid solution has been studied by Henderson et al. [484]. In this study, CV, electrochemical quartz crystal microbalance (EQCM), and probe beam deflection methods have been used. It has been found that Pb UPD proceeds in three steps. The first step comprised water ejection from the gold surface. This step was followed by metal UPD accompanied by the removal of the adsorbed OH. Also, Zeng and Bruckenstein have studied UPD and adsorption of Pb on pc-Au electrodes, applying XPS and TOF-SIMS method in case of 0.1 M NaCl electrolyte [485], and EQCM in case of 0.1 M NaCl04 and 0.1 M NaCl electrolytes [486]. In the presence of chloride anions, the adsorption of Pb—Cl complex has been found. 

Exchange of species between a solution and a polymer film is an established means of probing solution composition. The quartz crystal microbalance can monitor such exchange processes with high sensitivity. When combined with selectivity via electrochemical control and appropriate choice of polymer, the EQCM becomes an attractive sensor. In order that the potential advantages of the EQCM can be realised, certain criteria must be met. 

The electrochemical quartz crystal microbalance is a versatile technique for studying several aspects of electroactive polymer film dynamics. For rigid films, it is a sensitive probe of mobile species (ion and solvent) population changes within the film in response to redox switching. For non-rigid films, it can be used to determine film shear moduli. In the former case, one simply follows changes in crystal resonant frequency. In the latter case, the frequency dependence of resonator admittance in the... 

Kim NH, Baek TJ, Park HG, Seong GH (2007) Highly sensitive biomolecule detection on a quartz crystal microbalance using gold nanoparticles as signal amplification probes. Anal... 

Probing the Solid/Liquid Interface with the Quartz Crystal Microbalance... 

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