Quartz crystals Subject

This device employs single-stranded poly(adenylic acid) [poly(A)] as the chemical recognition agent. This species selectively recognizes its complementary polymer, poly(U), through hybridization to form a double-stranded nucleic acid. The poly(A) is immobilized onto the activated surface of a quartz piezoelectric crystal, which is a mass-sensitive transducer. Electric dipoles are generated in anisotropic materials (such as quartz crystals) subjected to mechanical stress, and these materials will... 

Fig. 2.5. Quartz crystal monitor response when a silicon surface, previously exposed to a high dosage of CF ions, is subjected to 500 eV O2 ion bombardment. The regions of this curve are dominated by the following phenomena ...

Because of its piezoelectric properties, synthetic CC-quartz is used for frequency control in electrical oscillators and filters and in electromechanical transducers. When mechanically stressed in the correct direction, CC-quartz develops an electric polarization. The opposite is also tme an applied electric field gives rise to a mechanical distortion in the crystal. Thin sections of quartz are cut to dimensions that produce the desired resonance frequency when subjected to an alternating electric field the vibrating crystal then reacts with the driving circuit to produce an oscillation that can be narrowly controlled. Quartz is ideal for this application because it is hard, durable, readily synthesized, and can be tuned to high accuracy, for example, quartz crystal clocks can be made that are stable to one part in 109. 

The first experimental evidence of SHG was reported by Franken et al. [98], who focused a ruby laser beam (kL = 0.694 nm) on a quartz crystal and analyzed the two outgoing beams by a standard method (the second-harmonic beam was observed in the UV region 2XS = 0.347 nm). This experiment was soon followed by a theoretical analysis by Armstrong et al. [99]. Since then many articles have appeared on the subject (bibliographies are presented in Refs. 100 and 101). 

In a typical quartz gage, a thin plate (lamina) is cut from a crystal in such a man-net that the flat, parallel faces of lamina are perpendicular to one of the three electric axes of quartz. When subjected to a compressional force transmitted by means of a piston (or a diaphragm), the lamina. presses against an anvil and as result of this action, very weak electric charges of opposite sign are devel-... 

Acoustic waves. The microbalance is generally based on quartz crystals which are mechanically distorted when subjected to an electrical potential. The source is usually an alternating frequency in the MHz region and will be perturbed by minor changes at... 

The term quartz crystal microbalance is an unfortunate name for this device for several reasons (1) The word crystal is redundant when it follows quartz, a crystalline material (2) the devices do not invariably act exclusively as microbalances, being subject to a number of other physical perturbations as well (3) the name could also correspond to a SAW, APM, or FPW device fabricated from quartz. The term thickness-shear mode (TSM) resonator follows the convention used for the SAW, SH-APM, and FPW notations in that it describes the nature of the acoustic mode upon which the device is based. 

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... 

Any type of acoustic transducer, such as quartz crystal microbalance (QCM) or surface acoustic wave device (SAW), is fundamentally based on the piezoelectric effect. This was first described in 1880 by Jacques and Pierre Curie as a property of crystalline materials that do not have an inversion centre. When such a material is subjected to physical stress, a measurable voltage occurs on the crystal surfaces. Naturally, the opposite effect can also be observed, i.e. applying an electrical charge on a piezoelectric material leads to mechanical distortion, the so-called inverse piezo effect. These phenomena can be used to transfrom an electrical signal to a mechanical one and back, which actually happens in QCM and SAW. Different materials are ap-pHed for device fabrication, such as quartz, Hthium tantalate, lithium titanate... 

Quartz docks eventually replaced the mechanical docks around the middle of the 20th century. A quartz dock or watch makes use of the piezodectric property of quartz crystal A quartz crystal, when subjected to a mechanical pressure, creates an electric fidd. The inverse is also tme—that is to say, the shape of the crystal changes when it is subjected to an dectric fidd. These principles are used to design clocks that make the crystal vibrate and generate an electric signal of constant fisquency. 

Crystal microbalance impactor— measures one-half of nuclei mode, all of accumulation mode and coarse particle mode subject to 0 (filter) 0.06 (last stage) 30 10 0.02 pg/stage 1 pg/m /stage Impaction, quartz crystal sensing... 

In the late 19 century, Pierre and Jacques discovered that quartz crystals produced an electric charge when deformed and, conversely, the crystals changed dimension when they were subjected to an electric charge. They named this phenomenon/)/ezoe/ecfr/c/(y. The same effect was observed when quartz crystals were exposed to thermal radiation this effect was called pyroelectricity. Some fluoropolymer crystals exhibit similar behavior, examples of which include polyvi-nylidene fluoride, polyvinyl fluoride, and fluorinated ethylene propylene copolymer. 

The present, most widely used, method of regulating modem timepieces is a quartz crystal. A properly oriented quartz single crystal will expand and contract at a very precise frequency when subjected to an oscillating voltage produced by an inductive-capacitive (L-C) circuit oscillating at about the same frequency as the crystal. The crystal fine-tunes the oscillating frequency of the current [f = 2n LCf where L is the... 

Nonsteady behavior of electrochemical systems was observed by Fechner as early as 1828 [ii]. Periodic or chaotic changes of electrode potential under gal-vanostatic or open-circuit conditions and similar variation of current under potentiostatic conditions have been the subject of numerous studies [iii,iv]. The electrochemical systems, for which interesting dynamic behavior has been reported include anodic or open-circuit dissolution of metals [v-vii], electrooxidation of small organic molecules [viii-xiv] or hydrogen, reduction of anions [xv, xvi] etc. [ii]. Much effort regarding the theoretical description and mathematical modeling of these complex phenomena has been made [xvii-xix]. Especially studies that used combined techniques, such as radiotracer (-> tracer methods) ig. 1) [x], electrochemical quartz crystal microbalance (Fig. 2) [vii,xi], probe beam deflection [xiii], surface plasmon resonance [xvi] surface stress [xiv] etc. have contributed considerably to the elucidation of the role of chemisorbed species ( chemisorption), surface reconstruction as well as transport phenomena in the mechanism of oscillations. 

In 1880, Pierre Curie and his elder brother Jacques Curie found that crystals of Rochelle salt could generate electric potential between opposing surfaces when the crystals were compressed in certain directions (i.e., piezoelectricity) [1]. Two years later, they confirmed that the reverse effect could also occur when the crystals were subjected to an electric field. However, the phenomenon of piezoelectricity and its converse piezoelectric effect did not receive much attention until the World War I when it was demonstrated that quartz crystals could be used as transducers and receivers of ultrasound in water to detect the submarine. In 1921, Cady made the first quartz crystal resonator based on the X-cut crystals [2]. But, the X-cut crystals exhibited very high temperature sensitivity, so that they could... 

The purpose of the present book is to satisfy this need. The book starts by covering the basic subjects of interfacial electrochemistry. This is followed by a description of some of the most important techniques (such as cyclic voltammetry, the rotating disc electrode, electrochemical impedance spectroscopy, and the electrochemical quartz-crystal microbalance). Finally, there is a rather detailed discussion of electroplating (including alloy deposition), corrosion, and electrochemical energy conversion devices (batteries, fuel cells and super-capacitors). 

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