Intermediate electrode

Laister and Benham have shown that under more arduous conditions (immersion for 6 months in sea-water) a minimum thickness of 0-025 mm of silver is required to protect steel, even when the silver is itself further protected by a thin rhodium coating. In similar circumstances brass was completely protected by 0 012 5 mm of silver. The use of an undercoating deposit of intermediate electrode potential is generally desirable when precious metal coatings are applied to more reactive base metals, e.g. steel, zinc alloys and aluminium, since otherwise corrosion at discontinuities in the coating will be accelerated by the high e.m.f. of the couple formed between the coating and the basis metal. The thickness of undercoat may have to be increased substantially above the values indicated if the basis metal is affected by special defects such as porosity. 

Inner electrode Substrate electrode Intermediate electrode External electrode... 

We can now return to the cell depicted in Equation (12.97). We must assume that the concentration of the solute is continuous across the boundary between the two solutions. Then the cell may be regarded as a series of cells given in Equation (12.101). In such a series the potential of the intermediate electrodes cancel, leaving only the potentials of the two end-electrodes. The emf of the cell is given by the integral of Equation (12.108) between the limits of xx and x2, where Xj locates some plane within the solution on the left where the concentration is definitely m2, and x2 locates a plane on the right where the concentration is definitely m2. Thus,... 

Photomultiplier tubes are a variation of the conventional phototube. Such tubes have several intermediate electrodes, known as dynodes, in addition to the primary photocathode and anode. Electrons emitted from the cathode strike the first of these dynodes, whereupon by secondary emis-... 

Determination of Transference Numbers.—Since activity coefficients can be derived from e.m.f. measurements if transference numbers are known, it is apparent that the procedure could be reversed so as to make it possible to calculate transference numbers from e.m.f. data. The method employed is based on measurements of cells containing the same electrolyte, with and without transference. The e.m.f. of a concentration cell without transference E) is given by equation (11), and if the intermediate electrodes are removed so as to form a concentration cell with transference, the e.m.f., represented by Et, is now determined by equation (25), provided the transference numbers may be taken as constant within the range of concentrations in the cells. It follows, therefore, on dividing equation (25) by (11), that... 

The ionization is achieved by a discharge between a cathode and an anode in which an exit hole is drilled. An intermediate electrode confines the discharge to a small region. The plasma extends through the anode aperture and the ions are extracted from the plasma surface by means of an extraction electrode. 

Use Agricultural fungicide, dye intermediate, electrodes for pH measurements, reagent. 

The quadrupole ion trap (QIT) mass spectrometer consists of three hyperbolic-shaped electrodes arranged in a cylindrical geometry (see Fig. 2.14). By considering its axial geometry, we can move from the classical Cartesian coordinates to the polar ones. In fact, each point of the space inside the trap can be defined by the value of its axial (z) and radial (r) coordinates. If a potential U + Vcos cot is applied at the intermediate electrode and the two end caps are grounded, a mathematical treatment analogous to that done for quadrupole mass filter can be employed. In this case, a and q values can be defined again as... 

Consider the case where U = 0 that is, any dc potential not given to the intermediate electrode. In this case, the stability diagram becomes a stability line, corresponding to q values between 0 and 0.908 (see Fig. 2.17). For suitable V, co, r0, and m/z values, all the ions follow trajectories confined inside the trap. By looking at Eq. 2.10, it follows that for V, co and r0 = const, ions of different m/z values exhibit q values inversely proportional to their m/z value, as schematized in Fig. 2.17. 

However, the Mathieu parameters a and q, defined by Eqs. 2.9 and 2.10, can still be employed for the description of the DIT theoretical stability diagram, considering the U and V values as the average values of the dc and ac components of the rectangular wave voltage applied to the intermediate electrode. They are defined as... 

Several thousand linear feet of additional intermediate electrode material has been supplied by Gore over the past year for use with this system... 

K. Fischbeck and E. Einecke found that the cathodic polarization of ferrous, cuprous, calcium, and magnesium chromites produces chromic acid, whilst the other chromites are unaffected, and natural chrome ironstone behaves in a like manner, but other commercial chromites are reduced on cathodic polarization, and yield chromic acid on anodic polarization. Chromites behave as an intermediate electrode. 0. Unverdorben observed that chromyl fluoride, prepared by heating a mixture of fluorspar, lead chromate, and sulphuric acid, when passed into water, furnishes an aq. soln. of this oxide. The soln. was treated with silver nitrate, and the washed precipitate of silver chromate decomposed by hydrochloric acid. A. Mans said that anhydrous sulphuric acid or fuming sulphuric acid is not suited for the preparation because of its volatilization with the chromyl fluoride. 

The most popular member of the plasmatron family is the duoplasmatron (O Fig. 50.3). Its idea is that the plasma density between the anode and cathode is greatly increased in a small volume by an intermediate electrode placed between the anode and cathode putting on... 

Dynodes are often placed between the photocathode and the anode as intermediate electrodes. High-quality photomultipliers have 10-14 dynodes (see Fig. 16). This internal amplification is critical because in addition to electrons from the light-induced process, other thermally activated electrons give rise to a dark current. Photomultipliers are therefore often cooled for the measurement of low light intensities. 

At room temperature, upon increasing the overpotential, the sequence of transitions in Equation 3.57 will give transfer coefficients and effective Tafel slopes b = RgT/(acF) of (i) Uc = 1 and b = 60 mV at high electrode potential, (ii) ac = 0.75 and b = 80 mV at intermediate electrode potential, and (iii) = 0.5 and b = 120 mV at low electrode potential. These values agree with those found by Sepa and Damjanovic. 

An electrode in an electrolytic cell that is not mechanically connected to the power supply, but is so placed in the electrolyte, between the anode and cathode, such that the part nearer the anode becomes cathodic and the part nearer the cathode becomes anodic. Also called an intermediate electrode. 

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