Quartz crystal microbalance method

A cooled quartz crystal microbalance methode for measuring diffusion pump backstreaming... 

Refs. [i] Vives AA (2004) Piezoelectric transducers and applications. Springer, Berlin [ii] Lu C, Czanderna AW (eds) (1984) Applications of piezoelectric quartz crystal microbalances (Methods and phenomena, their applications in science and technology). Elsevier, New York... 

A novel quartz crystal microbalance method has been described, which measures the concentration of the antibiotic chloramphenicol, via antichloramphenicol antibodies, which were covalently coupled to the monolayer on a gold surface [44], While this approach shows some promise, the system described was of low sensitivity, detecting only in the pM range. The development of highly sensitive recombinant antibody fragments to atrazine [45] and their potential for expression in multiple different structural formats [46] will greatly aid the development of rapid biosensors for environmental contaminants in the future. 

In order to study the structural correlation from layer to layer, we have successfully used a combination of the quartz-crystal microbalance method and u.v.-visible spectroscopy. A quartz-crystal microbalance, utilizing the change in the resonance frequency upon film deposition, provides a convenient method of determining the mass of the film. 

Water-methanol uptake from the vapor phase by PBI was determined in thin membranes (100 nm thick) using the quartz crystal microbalance method [280]. The results, expressed as moles of water plus methanol sorbed per imidazole ring, are shown in Fig. 6.31. It was assumed that the partition constant of methanol is Kx = 1.29, as determined by NMR analysis of a PBI membrane in equilibria with a methanol aqueous solution (20 wt%) [280]. 

M. H. Ho "Applications of Quartz Crystal Microbalances in Aerosol Mea.suremenls, in C. Lu, A. W. Czandema (eds.) "Applications of Piezoelectric Quartz Crystal Microbalances, Methods and Phenomena, vol. 7, Elsevier, Amsterdam 1984. 

Many different metals adsorb water in similar manners, forming metal oxyhydroxides. The exact nature of the oxyhydroxide formed seems to have only a minor influence on the water adsorption phenomena. The quantity of reversibly adsorbed water increases with relative humidity and time. Reference [1] refer to Table 2.3 for the approximate number of monolayers of water at 77°F/25°C and steady-state conditions, which have been experimentally determined by the quartz crystal microbalance method on a number of metals. ... 

K. Nakanishi, H. Muguruma, K. Ikebukuro, and I. Karube, A novel method of immobilizing antibodies on a quartz crystal microbalance using plasma-polymerized films for immunosensors. Anal. Chem. 68, 1695-1700 (1996). 

LB films of cadmium octadecanoate and other amphiphiles were transferred on a quartz-crystal microbalance (QCM, 9 MHz, AT-cut) as a substrate with a vertical dipping method. Frequencies of the QCM substrate were followed with time in air, after the QCM was raised from the interface. From the time courses of these frequency changes at each dipping cycle, the transfer amount of dry LB films (W ), the incorporated amount of water (W2), and its evaporation speed (v) could be obtained in nanogram level. 

The electrochemical quartz crystal microbalance (EQCM) method was first used to study underpotential deposition in 1988 for Pb, Bi, Cu,... 

Goodman, M.A. Vapor pressure of agrochemicals by the Knudsen effusion method using a quartz crystal microbalance, J. Chem. Eng. Data, 42(6) 1227-1231, 1997. 

A number of methods are available for the characterization and examination of SAMs as well as for the observation of the reactions with the immobilized biomolecules. Only some of these methods are mentioned briefly here. These include surface plasmon resonance (SPR) [46], quartz crystal microbalance (QCM) [47,48], ellipsometry [12,49], contact angle measurement [50], infrared spectroscopy (FT-IR) [51,52], Raman spectroscopy [53], scanning tunneling microscopy (STM) [54], atomic force microscopy (AFM) [55,56], sum frequency spectroscopy. X-ray photoelectron spectroscopy (XPS) [57, 58], surface acoustic wave and acoustic plate mode devices, confocal imaging and optical microscopy, low-angle X-ray reflectometry, electrochemical methods [59] and Raster electron microscopy [60]. 

A variety of surface-sensitive spectroscopic and microscopic methods were critical in the investigation of these systems. In the work by Advincula et al, the composition, thickness, physical and thermal properties, and morphology of the tethered polymer brushes were carefully analyzed [72]. A variety of surface-sensitive techniques such as ellipsometry, contact angle measurements, AFM, quartz crystal microbalance (QCM), FT-IR grazing incidence... 

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... 

On a pc-Au electrode in 1 M NaF vertically oriented pyridine molecules have been observed at 0.7 V (versus Ag/AgCl), applying in situ IR. In contrast, they have not been detected at this potential in electrochemical method [240]. Considering the fact that adsorption of pyridine on gold electrodes is a replacement reaction and taking into account the results obtained from quartz crystal microbalance experiments, the conclusion has been made that adsorption of one pyridine molecule is accompanied by the removal of 10-12 water molecules [241]. 

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. 

Variations on the vertical dipping technique have been utilized to construct films containing divalent metal ions. For example, the quartz crystal microbalance (QCM) has been used to evaluate the horizontal lifting method of CdSt LB Film construction (26). In this method, the QCM quartz plate was touched to monolayers compressed on a subphase and lifted horizontally. Y-type transfer (transfer ratio of 1) was demonstrated with two centrosymmetric monolayers deposited for each cycle. A combination of the vertical and horizontal dipping techniques has been utilized to prepare multilayer films from an amphiphilic porphyrin compound (27). 

Fig. 6.97. Some techniques used in the study of isotherms (a) Electrochemical quartz crystal microbalance mass change (AW) vs. quantity of electricity (AG) [Au, 0.1 M HCI04 (a), and 0.05 MH2S04 ( )] and anion coverage vs. electrode potential [poly-Au (open symbols), and Au(111) (dark symbols) HS04 (circles) and CI04 (triangles)]. Reprinted from H. Uchida, N. Ideda, and M. Watanabe, J. Electroanal. Chem. 42 , copyright 1997, Figs. 3 and 5, with permission of Elsevier Science.) (b) Specular reflection method reflectivity change vs. potential [Au, HCI04 with Nal (b) and (c) 0...

More recently, Tohidi and coworkers (Burgass et al., 2002 Mohammadi et al., 2003) have applied a novel method for measuring gas hydrate phase equilibria (Lw-H-V), which is based on a Quartz Crystal Microbalance (QCM). Figure 6.3 shows a schematic of the QCM set up and the QCM placed in a high pressure cell. The QCM consists of a thin disk of quartz sandwiched between two electrodes. The crystal will oscillate at a particular resonant frequency when an electric current is passed across the electrodes. This frequency is a function of the properties of the crystal. Any mass (from hydrate formation) attached to the surface of the crystal disk will cause a change in the resonant frequency, and hence be detected. The pressure and temperature of the system is measured using conventional methods, namely, a pressure transducer and a thermocouple in the high pressure cell. 

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