Microbalance technique

The principal of the vibrating quartz method is summarised simply. The mass, m, of the vibrating section of the crystal is 

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P. A. Cutting, in Vacuum Microbalance Techniques 7,51, Plenum Press, New York (1970). 

M. J. Pikal, S. Shah, D. Senior, and J. E. Lang, Physical chemistry of freeze drying measurement of sublimation rates of frozen aqueous solutions by a microbalance technique, J. Pharm. Sci., 72, 635-650 (1983). 

Improved Qartz Crystal Microbalance Technique J. Appl. Phys. 56, (3), 608-626 (1984)... 

Endres et al. [82] have demonstrated the suitability of an air- and water-stable ionic liquid for the electropolymerization of benzene. This synthesis is normally restricted to media such as concentrated sulfuric acid, liquid SO2 or liquid HF as the solution must be completely anhydrous. The ionic liquid used, l-hexyl-3-methylimidazolium tris(pentafluoroethyl)trifluorophosphate, can be dried to below 3 ppm water, and this ionic liquid is also exceptionally stable, particularly in the anodic regime. Using this ionic liquid, poly(para-phenylene) was successfully deposited onto platinum as a coherent, electroactive film. Electrochemical quartz crystal microbalance techniques were also used to study the deposition and redox behavior of the polymer from this ionic liquid (Section 7.4.1) [83]. 

The results of studies of copper surfaces by low-temperature adsorption isotherms may be summarized as follows. True surface areas of metallic specimens as small as 10 sq. cm. can be derived with a precision of 6% from low-temperature adsorption isotherms using vacuum microbalance techniques. This method is of special value in determining the average thickness of corrosion films formed by the reaction of gases or liquids with solids. The effect of progressive oxidation of a rough polycrystalline metal surface is to decrease the surface area to a point where the roughness factor approaches unity. 

The task of a precise evaluation of the boundary conditions of temperature and of film thickness for which their treatment is valid and of making a systematic correlation of the theory with precise experimental data over an appreciable temperature range is one for which vacuum microbalance techniques are well suited. This behavior is characteristic of many metals. A study of the low-temperature oxidation characteristics of single crystal faces of copper are described in some detail in the following paragraph as a typical example. 

One of the most important of these new experimental tools has been the development and application of the vacuum microbalance technique in which the sensitive microbalance operates directly in the vacuum or reaction system. The success of the method depends upon the coordination of a number of different experimental as well as theoretical disciplines. Thus, from an experimental point of view precise weighing techniques on properly prepared specimens must be coordinated with high vacuum techniques and the use of ceramic materials at high temperatures. From a theoretical viewpoint thermodynamic calculations must be made for all of the reactions involved and the results interpreted in terms of diffusion process for gas-solid reactions in which a film is formed or the gas diffuses into the solid, or in terms of the absolute reaction rate theory or its equivalent for gas reactions on solids including catalytic reactions and the combustion of fuels. 

Reaction of zirconium metal. Information concerning the gases that are present in the vacuum of the furnace unit can be obtained by suspending a specimen of zirconium metal in the vacuum system and measuring the rate of its reaction with the gases present. This can be readily achieved by the use of the vacuum microbalance technique which has been described. 

Su X, Wu Y-J, Knoll W (2005) Comparison of surface plasmon resonance spectroscopy and quartz crystal microbalance techniques for studying DNA assembly and hybridization. Biosens Bioelectron 21 719-726... 

Computer Controlled Vacuum Microbalance Techniques Of Surface Area And Porosity Measurements. K. A. Thompson and E. L. Fuller, Langmuir 3 (5) (1987)699-703... 

R. Staudt, G. Sailer, F. Dreisbach, M. Tomalla, J.U. Keller Determination of gas adsorption equilibria by volume-gravimetric measurements. In J.U. Keller, E. Robens (eds.) Microbalance Techniques. Multi-Science Publishing, Brentwood 1994, S. 205-210. 

O. jantti, J. Junttila, E. Yijanheikki On curtailing the micro-weighing time by an extrapolation method. In T. Cast, E. Robens (eds.) Progress in Vacuum Microbalance Techniques, Vol. 1. Heyden, London 1972, p. 345-353. ISBN 0 85501 073 8. 

E. Robens, J.A. Poulis, C.H. Massen Fast gas adsorption measurements for complicated adsorption mechanisms. In V.A. Tertykh, V. Pokrovskiy (eds.) Proceedings of the 28 International Conference on Vacuum Microbalance Techniques, 1999, Kyiv. Journal of Thermal Analysis and Calorimetry 62 (2000) 429-433. 

The electrochemical reduction of Ti02 is known to be accompanied by the intercalation of small cations. This finding has been explored in sensitizing anatase films for battery applications [149]. Cation coordination to titanium alkoxide sol-gel precursors is also well known [150]. Lyon and Hupp used quartz crystal microbalance techniques to determine the mass of intercalating cations as the TiOa film is reduced [151]. Hagfeldt and co-workers have studied Li+ and Na intercalation into anatase Ti02 both theoretically and experimentally [152, 153). They found that the diffusion constants for Li and Na+ are temperature dependent with an activation barrier of 0.4 eV for insertion and 0.5 eV for extraction. The Li+ diffusion coefficient at 25 °C into the nanoporous structure was approximately 2 X 10 cm s for insertion and 4 x 10 cm s for extraction. 

The studies of adsorption capacity of vapors were made by microbalance technique, and kinetic characteristics were determined on a dynamic apparatus. The statics of vapor adsorption was studied at 20 °C. 

Recently, Feldmann and Melroy [131] utilized a quartz microbalance technique to simultaneously determine the net current and the partial anodic and cathodic currents in a single complete electroless copper bath. The cathodic current is calculated by converting the deposition rate measured with the microbalance into the unit of current, while the anodic current is computed by subtracting the cathodic current from the net current measured directly on the microbalance electrode. Using this technique, Feldmann and Melroy showed that the potential at which the reduction of the Cu-EDTA complex begins at 70 °C shifts by as much as 0.3 V in positive direction upon addition of formaldehyde. It was also shown that at a given potential, the rate of copper deposition increases with increasing formaldehyde concentration (Fig. 23). The observed catalytic effect of formaldehyde is attributed to an interaction between formaldehyde and the Cu-EDTA complex, possibly to the formation of Cu(EDTA)/formaldehyde complex. However, the detailed mechanism of this catalytic effect has not been clarified. 

INVESTIGATION OF HORSERADISH PEROXIDASE ADSORPTION ON GOLD AND POLYSTYRENE SULFONATE MODIFIED SURFACES BY QUARTZ CRYSTAL MICROBALANCE TECHNIQUE... 

Fig. 10. Schematic diagram of a recording microbalance. From L. Cahn and H. R. Schultz, in Vacuum Microbalance Techniques, Ed. K. H. Behmdt, 3 (1963) 30.

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