Polonium ion

There are a series of papers that focus on the behavior of the radon decay products and their interactions with the indoor atmosphere. Previous studies (Goldstein and Hopke, 1983) have elucidated the mechanisms of neutralization of the Po-218 ionic species in air. Wilkening (1987) reviews the physics of small ions in the air. It now appears that the initially formed polonium ion is rapidly neutralized, but can become associated with other ions present. Reports by Jonassen (1984) and Jonassen and McLaughlin (1985) suggest that only 5 to 10% of the decay products are associated with highly mobile ions and that much of the activity is on large particles that have a bipolar charge distribution. 

It has been reported for many years that condensation nuclei can be produced by ionizing radiation. Recent studies have improved the measurement of the activity size distribution of these ultrafine particles produced by radon and its daughters (Reineking, et al., 1985 Knutson, et al., 1985). It seems that the Po-218 ion is formed by the radon decay, is neutralized within a few tens of milliseconds, and then attached to an ultrafine particle formed by the radiolysis generated by the polonium ion recoil. Although there will be radiolysis along the alpha track, those reactions will be very far away (several centimeters) from the polonium nucleus when it reaches thermal velocity. The recoil path radiolysis therefore seems to be the more likely source of the ultrafine particles near enough to the polonium atom to rapidly incorporate it. 

At higher humidities, more neutralization occurs leading to fewer polonium ions that can be observed. 

When the flow through the CNC was exhausted outside of the laboratory, we observed particle formation at higher SOp concentrations as expected (Table II). To prove that the radical scavenger effect is reproducible, another radical scavenger (92 ppb nitric oxide) was used in the presence of 110 ppb SOp concentration and 2% humidity, and the supression in particle formation was observed. Another possible mechanism that supressed the particle formation is that more neutralization of polonium ions occurred at the higher humidities and thus ion-induced nucleation would be suppressed. 

SULPHUR, SELENIUM, TELLURIUM AND POLONIUM IONS IN AQUEOUS SOLUTIONS... 

Pseudohalides of Se in which the role of halogen is played by cyanide, thiocyanate or selenocyanate are known and, in the case of Se are much more stable with respect to disproportionation than are the halides themselves. Examples are Se(CN)2, Se2(CN)2, Se(SeCN)2, Se(SCN)2, Se2(SCN)2. The selenocyanate ion SeCN is ambidentate like the thiocyanate ion, etc., p. 325), being capable of ligating to metal centres via either N or Se, as in the osmium(IV) complexes [OsCl5(NCSe)], [OsCl5(SeCN)], and trans-[OsCU(NCSe)(SeCN)]2-.920) Tellurium and polonium pseudohalogen analogues include Te(CN)2 and Po(CN)4 but have been much... 

Polonium forms both 4+ and 6+ ions, the former being considerably more stable in... 

Both polonium nuclides are alpha emitters and therefore of particular concern. In health physics it is customary to differentiate between attached and unattached 218Po the former, usually the larger of the two consists of 218Po atoms attached to airborne particles which are copiously present in virtually every atmosphere the latter consists of a 218Po atom or ion, frequently surrounded by several dozen molecules of a condensible species present in the air. The purpose of this paper is to present a new method for measuring the size properties of these unattached 218Po clusters. 

Radon daughters are deposited on the surface of mucus lining the bronchi. It is generally assumed that the daughter nuclides, i.e. polonium-218 (RaA), lead-214 (RaB) and bismuth-214 (RaC), remain in the mucus and are transported towards the head. However, one dosimetric model assumes that unattached radon daughters are rapidly absorbed into the blood (Jacobi and Eisfeld, 1980). This has the effect of reducing dose by about a factor of two. Experiments in which lead-212 was instilled as free ions onto nasal epithelium in rats have shown that only a minor fraction is absorbed rapidly into the blood (Greenhalgh et al., 1982). Most of the lead remained in the mucus but about 30% was not cleared in mucus and probably transferred to the epithelium. 

Element 116 was also directly produced by bombarding atoms of curiiim-248 with ions of high-energy calcium-48 ions. At the bottom of group 6 (VIA) on the periodic table, Uuh is presumed to have some of the properties and characteristics of its homologues polonium and tellurium, located just above it in this group. 

At trace levels, polonium can be separated effectively by solvent extraction, ion exchange, paper chromatography, and other techniques. Diisopropyl ketone, di-n-octylamine, and tri-n-butylphosphate are suitable solvents for extraction. Trace amounts of polonium in solutions or sohd mixtures containing no other emitters can be determined by measuring its alpha activity. 

Their joint papers on The numbers of ions produced by alpha rays of radium C in air were published in the Comptes rendus in 1928. In the following year they investigated the nature of the absorbable radiation which accompanies the alpha-rays from polonium. In 1930 M. Joliot presented his thesis for the doctorate, which was entitled The electrochemistry of the radio-elements, and Mme. Joliot continued her study of polonium (123). 

In the final purification, polonium is either dissolved in nitric acid and clectrodeposited onto platinum, or, better, gold (6, 25) the polonium is sublimed in a vacuum from the support metal or dissolved off the latter in dilute hydrochloric acid and precipitated as the monosulfide. Either hydrogen sulfide itself or the sulfide ion produced by the hydrolysis of thioacetamide may be used. The monosulfide is decomposed by heating under vacuum and the pure metal sublimed (14). 

Solvent extraction by tributyl phosphate (TBP) (13, 96), dithizone (20, 71, 72), cupferron (89), thenoyl trifluoroacetone (TTA) (55), diiso-propyl ketone (26), mesityl oxide (92), tri-n-benzylamine and methyl di-n-octylamine (99), diisopropyl and diisobutyl carbinol (100) have all found some application on the trace scale. Acetylaeetone and methyl isobutyl ketone extract milligram amounts of polonium almost quantitatively from hydrochloric acid, but the stable polonium-organic compounds which are formed make it difficult to recover the polonium in a useful form from solutions in these ketones (7). Ion exchange (22, 115, 119) and paper chromatography (44, 87) have also been used for trace scale separations of polonium, but the effects of the intense alpha-radiation on organic com-... 

A white solid, possibly polonium tetrafluoride, is obtained by treating polonium hydroxide or tetrachloride with dilute aqueous hydrofluoric acid treatment of this solid, in suspension in dilute hydrofluoric acid, with sulfur dioxide yields a bluish grey product (possibly PoF2) which rapidly reverts to the original white solid on standing, presumably owing to radio-lytic oxidation 12). The solubility of polonium(IV) in aqueous hydrofluoric acid increases rapidly with acid concentration, indicating complex ion formation (/ft), p. 48). 

There have been some unsuccessful attempts to prepare a volatile hexafluoride from fluorine and polonium-210 26, 104), but recently such a fluoride has been prepared in this way from polonium-208 plated on platinum 132). The product appears to be stable while in the vapor phase, but on cooling a nonvolatile compound is formed, probably polonium tetrafluoride resulting from radiation decomposition of the hexafluoride. Analytical data are not recorded for any polonium fluoride, largely owing to the difficulty of determining fluoride ion accurately at the microgram level. 

Early trace level work 52) with polonium suggested the presence of the hexachloropolonite (PoCh ) ion in hydrochloric acid solution more, recent work (9) with wcighable amounts of polonium indicates that the equilibrium constant for Po4+ + 6Cl- PoCl6— is about 1014. The molar absorbancy... 

The white basic selenate, 2Po02Se03, is obtained by treating polonium V) hydroxide or chloride with selenic acid (0.015 iV-5.0 N) the salt is yellow above 250°C and is stable to over 400°C. It is rather less soluble than the basic sulfate, but the solubility increases a hundredfold in passing from 0.05 N to 5 N selenic acid (10), indicating complex ion formation. 

This salt is a white crystalline solid made by treating polonium (IV) hydroxide or chloride with dilute acetic acid. Its solubility in the latter increased from 0.2 mg (of Po210)/liter in 0.1 N acid to 82.5 mg/liter in 2 N acid, indicating complex ion formation. The acetato complex is colorless in solution and appears to be more stable than the hexachloro complex (11). 

Ion exchange and solvent extraction data indicate that the compound contains one diethyldithiocarbamate ion attached to each polonium atom. It sublimes at about 110°C (81). 

This is a white crystalline solid obtained by treating polonium(IV) hydroxide or chloride with aqueous oxalic acid solubility studies indicate complex ion formation (11). 

The basic salts of quadrivalent polonium, such as the sulfate and sele-nate, show a marked resemblance to those of tellurium and further resemblances appear in the quadrivalent halides, particularly in their complexing with halide ions in solution, while complexing of polonium(IV) with weak acids, such as acetic, oxalic and tartaric, seems to be more marked than is the case with tellurium. 

Studies of the solubility of polonium(IV) in formic, acetic, oxalic and tartaric acids have provided evidence of complex formation,48 with the acetato complex emerging as more stable than the hexachloro anion. Other studies of the solubility of polonium(IV) hydroxide in carbonate49 and nitrate50 solution, together with investigations51 of the ion exchange behaviour of polonium(IV) at high nitrate ion concentration, have been discussed in terms of the formation of anionic complex species. 

The tendency of the chalcogens to show increasing metallic character as one moves down the periodic table is quite marked for polonium in fact, it resembles lead more than it does tellurium Its compounds have a more ionic character in its lower oxidation states than do the tellurium compounds. The stability of the 6+ state is low. the existence of polonate(VI) ion being doubtful. The common oxidation states of the element are 2+ and 4+. 

The product in this case is sodium aluminate, a compound that contains the aluminate ion, [Al(OH)4]. Because aluminum oxide reacts with both acids and bases, it is classified as amphoteric. Other main-group elements that form amphoteric oxides are shown in Fig. J.3. As you can see, these elements lie in a diagonal band across the table from beryllium to polonium. The acidic, amphoteric, or basic character of the oxides of the d-block metals depends on their oxidation state (see Chapter 16). 

The binuclear terbium centers and type I rotaxanes form a two-dimensional layer. Stacked layers are further interconnected via type II rotaxanes to form a three-dimensional polyrotaxane network, which has an inclined a-polonium topology with the binuclear terbium centers behaving as six-connected nodes (Fig. 20.4.10). The void space in the crystal packing is filled by a free rotaxane unit, NOJ and OH- counter ions, and water molecules. 

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