Cesium electrode

Many other cyclic and noncyclic organic carriers with remarkable ion selectivities have been used successfiilly as active hosts of various liquid membrane electrodes. These include the 14-crown-4-ether for lithium (30) 16-crown-5 derivatives for sodium bis-benzo-18-crown-6 ether for cesium the ionophore ETH 1001 [(R,R)-AA -bisd l-ethoxycarbonyl)undecyl-A,yVl-4,5-tctramcthyl-3,6-dioxaoctancdiamide] for calcium the natural macrocyclics nonactin and monensin for ammonia and sodium (31), respectively the ionophore ETH 1117 for magnesium calixarene derivatives for sodium (32) and macrocyclic thioethers for mercury and silver (33). 

A thorough insight into the comparative photoelectrochemical-photocorrosion behavior of CdX crystals has been motivated by the study of an unusual phenomenon consisting of oscillation of photocurrent with a period of about 1 Hz, which was observed at an n-type CdTe semiconductor electrode in a cesium sulfide solution [83], The oscillating behavior lasted for about 2 h and could be explained by the existence of a Te layer of variable width. The dependence of the oscillation features on potential, temperature, and light intensity was reported. Most striking was the non-linear behavior of the system as a function of light intensity. A comparison of CdTe to other related systems (CdS, CdSe) and solution compositions was performed. 

Ghen, R. Y., Hussey, G. L., Electrodeposition of cesium at mercury electrodes in the tri-l-butylmethylammonium bis((trifluoromethyl)sulfonyl)imide room-temperature ionic liquid, Electrochim. Acta, 49, 5125-5138, 2004. 

Figure 4. Free energies of transfer of sodium, lithium and cesium fluoride from water to hydrogen peroxide derived from measurements with ion-selective glass and fluoride electrodes (27)...

Fig. 1. Simultaneous separation and detection of anions and cations on a latex agglomerate column. Column Dionex HPIC-CS5 cation exchange column (250X2 mm) with precolumn HPIC-CG5 (50 X 4 mm) eluent 0.5 mM copper sulfate, pH 5. 62 flow rate 0.5 ml/min sample volume 20 gl containing 0.1 m M of each ion detection two potentiomet-ric detectors equipped with different ion-selective electrodes in series. Peaks (1) chloroacetate, (2) chloride, (3) nitrite, (4) benzoate, (5) cyanate, (6) bromide, (7) nitrate, (8) sodium, (9) ammonium, (10) potassium, (11) rubidium, (12) cesium, (13) thallium. Reprinted with permission from [10].

The increasing threat of international terrorism was one motivation for development of ISE for the determination of Cs+ in environmental samples [80]. In an event such as a Chernobyl-type disaster or the explosion of a dirty bomb , cesium is one of the most important reaction products and is expected to be the most significant threat to public health [81]. With a detection limit of 10 8M, the developed electrode is sensitive enough for this application and the successful detection of cesium activities in spiked water samples has been demonstrated (see Procedure 2 in CD accompanying this book). In addition, the electrode shows excellent selectivity to cesium in the presence of high levels of strontium, an important interferent originating from nuclear explosions. 

Determination of cesium in natural waters using polymer-based ion-selective electrodes... 

Table 2.2 summarises the results obtained for all of the water samples. A very good correspondence between spiked and experimentally obtained results was observed. A relative experimental error in most cases was <10% indicating the possibility of using these electrodes as an early warning system in the event of a large contamination of natural waters with cesium, such as in the event of a nuclear reactor accident, e.g., Chernobyl, or the detonation of a dirty bomb . 

It is noteworthy to mention that under normal conditions, cesium is not considered a major contaminant of natural and ground waters since it preferentially adheres to soils, thereby showing relatively low mobility. Therefore, a cesuim-selective electrode for the successful determination of cesium in natural waters that exhibits negligible interference by strontium was characterised and developed utilising UIC as the ion exchanger. 

Rates of ion exchange on kaolinite, smectite, and illite are usually quite rapid. Sawhney (1966) found that sorption of cesium on illite and smectite was rapid, while on vermiculite, sorption had not reached an equilibrium even after 500 h (Fig. 5.5). Sparks and Jardine (1984) found that potassium adsorption rates on kaolinite and montmorillonite were rapid, with an apparent equilibrium being reached in 40 and 120 min, respectively. However, the rate of potassium adsorption on vermiculite was very slow. Malcom and Kennedy (1969) studied Ba-K exchange rates on kaolinite, illite, and montmorillonite using a potassium ion-specific electrode to monitor the kinetics. They found >75% of the exchange occurred in 3 s, which represented the response time of the electrode. The rate of Ba-K exchange on vermiculite was characterized by a rapid and slow rate of exchange. 

Initially, 1.3 g (2.1 X 10-3 mole) of Cs2 [Pt(CN)4] H20 is dissolved in 7 mL of water to produce a saturated solution (it may be necessary to warm the solution slightly to dissolve the Cs2[Pt(CN)4] H20). The solution is transferred to a 50-mL polyethylene beaker and 1.7 g (1.1 X 10-2 mole) of cesium fluoride is added. The white CsF appears to become yellow after it is added. It then dissolves, leaving a white suspension. Finally, 7.6 M CsOH is added to the solution dropwise to raise the pH from approximately 4 to 9 ( 0.2). The pH of 9 must be carefully maintained throughout the reaction. The electrolysis cell consists of a 50-mL polyethylene beaker with two small holes drilled about 6 mm from the bottom and on opposite sides. Two platinum wires about 25 mm in length are used as electrodes. They are held in place with Apiezon N grease. The electrodeelectrode separation is approximately 5 mm. The power source is a 1.5 V dry cell. 

A dramatic cesium effect was found by Weber in the case of the synthesis of the tetrabenzo crown ether 31, which is of interest for applications in ionselective electrodes [39]. The cyclization reactions starting from the cesium phenolate obtained from 29 and the tosylate 30 under high dilution conditions in DMF led to 31 in 37 % yield. This is a dramatic improvement of the formerly obtained yield of only 6 % in the system KOH/ -butanol/ethanol/DMF [40]. 

Thermionic converters are high temperature devices which utilize electron emission and collection with two electrodes at different temperatures to convert heat into electric power directly with no moving parts. Most thermionic converters operate with a plasma of positive ions in the interelectrode space to neutralize space charge and permit electron current flow. Both the plasma characteristics and the surface properties of the electrodes are controlled by the use of cesium vapor in thermionic diodes. 

The unique properties of cesium play a crucial role in the operation of thermionic converters. Cesium functions both as adsorbed atomic layer to produce the required work functions on the electrodes, and as a plasma medium to form Cs ions which neutralize space charge in the interelectrode region. Cesium is desirable as the plasma medium because of its low ionization potential and large atomic mass. Since the surface adsorbed layers are continuously evaporating and being replenished by cesium atoms refluxing from the vapor, the surface properties are very stable. Thermionic converters have operated with no change in performance for more than 5 years. 

The electron space charge barrier to current flow can be neutralized by providing heavy cesium ions. Cesium is a particularly good choice because it has the lowest ionization potential of any element and a large atomic mass 133 amu, which causes the mobility of ions leaving the plasma to be low. The ions are produced in a low voltage arc between the electrodes. 

Both analysis give logical results. As expected, the coefficient 02( 2) in both analyses decreases significantly when going from Li to Cs. However, even in the case of cesium, they still have a significant value, which indicates that such a system would not serve properly as a reference electrode in various nonaqueous solvents. The U] values in Table 3 represent the half-wave potentials at DN = 0, i.e. in... 

Fig. 3 Flame housing of IL 943 flame photometer a) sodium filter, 589 nm b) potassium filter, 776 run c) lithium filter, 670 nm d) cesium filter, 852 nm e) ignition detector f) burner assembly g) rubber gasket h) spark electrode i) ignition coil wire j) chimney. (Courtesy of Instrumentation Laboratory, Inc.)...

Judging from the present OLED status, the most important research was Partridge s report on the EL utilized poly(vinyl carbazole) (PVCz) thin films in 1982.26-29 He used the 500-nm-thick PVCz thin films doped with fluorescent molecules as an emissive center, equipped with the efficient hole-injection electrode (SbCls/PVCz) and the electron-injection electrode (cesium) as a low-workfunction metal. Although no quantitative measurement of luminance was described, surprisingly the injection current density reached 1 mA/cm2. Nowadays, we can fabricate very similar OLED devices with superior EL performance. Thus, Partridge s device contributed to establishing the prototypes of present OLED devices. 

Johansson, G., Risinger, L., and Faelth, L. 1977. A cesium-selective electrode prepared from a crystalline synthetic zeolite of the mordenite type. Analytica Chimica Acta 119, 25-32. 

The most reliable value was determined by Harima and Aoyagui 5 ) who obtained the same standard potentials against a backround of lithium, sodium, potassium, and cesium salts. Together with Kurihara they have also determined the standard potential of the electron electrode in methylamine. 

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